Difference lead acid battery and closed lead batteries + interchangeable chargers?

I found a 6v closed lead battery as found in UPS systems. I'd like to get in in condition again and found a schematic for a charger/revitalisor for motorcycle batteries. But those are open batteries, and I found chargers specifically for that type somewhere as well. Could I use it anyway or is that a bad idea?

Question by Fozzy Vis   |  last reply


Why dont they use alcohol in closed system steam engines? Other than safety?

By closed system i mean constant mass of working fluid.  i.e. no steam leaving system, like an air conditioner. My point is that alcohol has a lower boiling point that water, (some kinds can boil from the heat of your hand!). SO other than the safety problem of alcohol being flamable, alcohol could operate with a lower heat input than water.    With the addition of a cold resivoir, the closed system alcohol steam engine could work right? Or why not use a refridgerant gas in a closed system steam engine cycle,? >Which would effectively absorb the heat input any ideas? addition*  I mean for use in any steam engine with a closed loop cycle, like the Rankin cycle   http://en.wikipedia.org/wiki/Rankine_cycle

Question by MechEngineerMike   |  last reply


Designing a different / customized kind of computer system?

I've read about how when you Install the windows OS onto a usb stick It's unique to that computer (b/c of specific drivers, specs, hardware etc... and yes, It Is possible with some tweaking, don't spout out propaganda you're fed from Microsoft and apple). I'd like to know what it would take to design a generic computer that all you would have to do is plug in your personal drive and your OS (whichever it may be) and files are programs all there ready for use. And also be made in such a way that if the 'terminal' were duplicated part for part, no matter which one your drive was plugged Into It, would work the same. I'm thinking of designing a kind of system like this- drawing on elements from sci-fi (which is obversely based on the real world) In Stargate Atlantis and Battlestar Galactica (reimagined version). In Stargate Atlantis, Atlantis Is a cIty-shIp that has In Its Infrastructure the hardware, database, and OS, which is accessible from the hundreds of terminals throughout; each one is like a separate pc but are all connected to the database and processing power of the city as a whole. In a similar way, In Battlestar Galactic, the Galactica class Battlestar has a closed network which they rely on Instead of wireless to prevent cyber-attacks from the cylons... but the only advantage I care about Is that data transfer Is much faster via wires, and fiber optic cable even more so. With the amount of products and parts available on the market today, budget is the only limiting factor. I know many people are programmed to say, "It’s not possible" or immediately shoot it down by saying how hard it would be, and that I should just buy a computer and be happy. But I am not just a consumer, I’m an artist, a designer, I’m not going to let other people call the shots just so they get a profit. Now I know Linux has the sort of open source availability I like, but I’m not too familiar with It and I’d like the project to be user friendly as well as geek friendly If the user so chooses (like an optimized combination of apple, Microsoft, and Linux). I will no doubt read around at the library and online, but I wanted to hear from people who already have experience and know what I’d be better off learning and what I’d be better off skipping altogether.

Question by ranosonar 



Help needed making a pause system for smartphone headphones

Hi guys, I'd like to take an existing pair of headphones (not a specific pair, I can buy a suitable pair if this will make things easier) and implement a switch that will automatically pause my android music when a switch is pressed. Specifically, I'd like the music to pause when a circuit is broken. Since Android will automatically pause music when the headphone jack is removed I can't imagine this would be too difficult to build. However I would also like the music to automatically start again when the circuit is closed again. I'm not overly tech savvy but I think this project is within the realm of my capabilities! Any thoughts or help would be much appreciated! Regards, Tig

Topic by tig5   |  last reply


Digital Logic Design Project Combinational Lock?

In this project you are required to design a 4 digits combination lock (not using arduino)  The project is such that it can be reconfigurable i.e. there should be an option that we can change the password of the lock at run time. Input to the system is from the hex keypad. Output of the system is ‘open’ and ‘close’ words displayed on a seven segment I used registers,flip flops, mux ,comparator  but couldn't get the desired result

Question by r_sammad   |  last reply


How to create motor or generator resistance system for exercise machine?

Researching a method to use resistance from a motor or generator for an exercise machine.  There is an axle from which both foot and arm levers extend, so there is rotation, but only about a half turn in each direction, so very low speed, and back and forth.  I have used magnets and eddy current and flywheel from exercise bikes, geared up with a belt.  This works ok, but does not provide enough resitance even when magnets are adjusted very close to flywheel (due to low speed of rotation). I hope to find something already built and available for a similar application, but can locate parts and build it if I understand how.  Resistance must be variable from low to very strong and controllable so user can adjust it.  I have DC motor, and shorting the cord greatly increases the drag, but how do I vary/control it?  Would adding resistance between the wires in the cord increase drag and make it harder to turn?  I have experimented with this and it does not seem to have an impact.  Thanks for your help.

Question by zanimann   |  last reply


The future of mobile operating system or the end for "hackers" and rooting?

For mayn years it was almost logical to get full root access on your new smartphone or tablet.The other fraction might now it as "jailbreaking"...No one really needs it unless they are not happy with they way the mnufacturer designed the operating system and features.The removal of bloat, apps the user never needs, is still the most common reason for rooting.Custom ROM's offering a different experience are right behind.Now we also have TV's, entertainment boxes of all kinds, even from our ISP's directly.The main provider for the operating system is now Google with only a few "competitors" left.Apple has a strong hold of the mobile and tablet sector too but is not really presented in other areas.Android is still open source but Google heavily modifed it to suit the needs of data collecting and security for features like banking, access control and so on.What is good for the normal user and perfect for those with security in mind can be really bad for those actually just using a device.No matter why you buy a new phone from your provider, you almost never buy it for the added apps and services.Rooting has become more and more difficult.One reason of course is constant security updates and removing possible access options for even simple things like getting USB debugging and an unlocked bootloader.People dedicated to find ways to remove provider locks, creating custom firmwares or the basic tools required to work with firmwares were called hackers.If you buy a new car and decide to modify it with a new engine, seats or whatever than no one will stop you.So why don't we have the same rights for our electronic companions?I wouldn't call it hacking, I would call it actually owning and controlling your device instead of Google letting control you - or Apple, but who cares....The other reason is dead simple: Those guys who started it all have retired or found employoment with those they fooled for so many years.Chainfire should ring a bell for anyone ever concerned with rooting.The master is gone now and only a few people are willing to take his legacy.For Asian devices the community over there is better off but for our market region right now Magisk seems to be the only option left for modern devices.The sneaky ways to lock us out....Security comes at a price, simple as.You can offer secrity for money transfers if the device is not trustworthy.Same for online streaming - you want the money for what you give and prevent that someone is able to make unwanted recordings without encryption.The list goes on with access control system and literally everything we use our devices for that involves some security.Even with the lates PIE systems Google's own devices are still quite friendly in terms of gaining root access.Different story though if a manufacturer makes full use of all the latest addition at Google's disposal.Device security no longer starts with the boot we see.It is now possible to create a hardware based tree of trust.This means any modification to anything will cause a failure.This locks out all "tools" able to read out partitions and vital data while a device is in fastboot mode.And of course said fastboot can be fully disabled as well now.For security reason a so called A/B configuration is used.Updates come over the air and are applied to the dormant system.Next start will boot the new system and then update the old one, no requirement to manually apply and update.The recovery can also be abandoned and replaced by a system using a copy on the device itself that is updated through OTA updates with the firmware.So both ways to gain official access can be full removed from the user.From there we get encryption, hash checks and literally everything working in its own user space - a full SELinux enviroment at the highest level.There are already devices utilising a lot of this and so far the only way to get any sort of insight was done by those intercepting OTA updates on a router level.And apart from quickly changing the encryption with the next updates nothing was gained.Is it all coincidence?Of course not.Well known leaks were kept open for years.Kernel updates gave improvements and closed really old leaks but never all known ways.With the retirement of the best rooting experts these holes were suddenly closed.Checks of latest kernel releases showed that there is no known vulenerabilities anymore that can be misused to gain access.And those finding new ones and making them available for us are bascally gone now.Encryptions and packing algorithms changed, same thing for the actual handling of partitions and rights.Anyone with a decent understanding of how the old ways worked will be able to figure it out with some time wasted on it.From there however the outcome is often dark.The tools needed to work with these new files are not always updated anymore.The developer simply moved on and most of the time without publishing his source codes.And the still best way to protect your firmware from tampering is to encrypt it.In the old days it was enough to sign a ZIP file with a release key not available to the public.Custom recoveries allowed us to get around this.This still works to some extent but now we also get additional checks starting from the bootloader.A modified system will be detected and stopped and a stock system will stop i a modified boot is detected.Even using a custom recovery by flashing or through fastboot is preventable now.Right now the only way for most new devices is a total wipe and the installation of an unsecure firmware with everything.As you already guessed this is to prevent now as well.So does all this rooting stuff actually concern you?Of course not!If you never had any need for rooting or no clue what to do differently with a rooted device than you are a happy camper.But your neighbour or friend might think differently.You see, I have two problems when it comes to "stock" devices.a) I have no clue what data they collect from me and what it might be used for.b) I do not like being forced to agree to terms that are endless and of questionable content just to use the damn thing.For crying out loud: In most cases it is now impossible to even set up a new device without working internet and a Google account.....

Topic by Downunder35m 


How would you make a visual notification system for when the mail comes? Answered

We have a long curving driveway so you can't see the end where the mailbox is. We end up checking the mail a couple times a day if waiting for something important. I've always wanted to do up some kind of thing where a light comes on when the mail is delivered by way of a switch that is turned on by the action of opening and closing the mailbox. Problem is that the mailbox is a good hundred feet from the nearest window on that side of the house (which is where i'd like the light to be) A wireless setup would be nice, but probably more complicated. Power down by the mailbox is available but house power for the driveway lights.

Question by siamonsez   |  last reply


Automatic Blind Opener Advice

Hi, I am thinking of putting together something that will able to automatically open and close my blinds as the darkness outside dictates. Ideally, I am hoping to attach the opening/closing pole to a DC Motor, which would be controlled by a light sensor. I was also toying with the idea of powering the system with a rechargeable 9V battery that could be topped up with a small solar panel attached to the window. Is this idea doable and, if so, any advice on parts and putting it together would be very much appreciated.

Topic by elsmandino   |  last reply


can someone look at this (simple) electricicity generation proposal and give me some tips. (with pictures)?

I want to use the wallpaper stripper for the prototype and if it works replace it with a combined heat, cooking, hot water system. Will adding the hydro have an advantage. the main reasoning behind this is using steam but not in a closed system as I dont have the engineering skills to mess about with high pressure steam. Any input is really appriciated. i have wasted enough time making things that will never be effective before finding instructables.

Question by mrgre99   |  last reply


parallel port input?

Plz help me to, how can i receive signal or instruction from paralel port, how should i send current/signal to its register. what equipment should i need. actually i want to develope a system in c language to control electricity of home, doors or widows, so i need to check that if the door is open or closes. when door closed then computer should indicate me that the door is closed, and same door has opened. sir plz give me guideline. i would be very very thankfull to u. ( simply tell me how current/data/signal can be sent through parallel port, current source, equipment ets, after that i will make sensers for it my self)

Question by    |  last reply


How can I change a normally open switch to a normally closed. My Alarm panel needs NC and my boiler alarm is NO.

I want to attach my boiler to my alarm panel to an extra zone I have.  Problem is my alarm panel wants to see it NC until there's trouble and then wants to see it NO when it's tripped or in alarm.  My boiler alarms points are NO until the boiler goes into lock out and then it goes NC.  I would like to know if there is a way to add "something" so that i can monitor my boiler and know if it goes into alarm.  My boiler is a Weil Mcclain Ultra seris 3 with a U-control system if that helps.

Question by Stuwho   |  last reply


PIR motion sensor,DC motor and Speaker alarm system help? Answered

I'm trying to create an alarm system using a PIR motion sensor, DC motor and a speaker so when someone gets close to it the DC motor should vibrate and sound and alarm through the speaker. (using and Arduino UNO) I've got  an external 9V battery powering it. the PIR and sound works fine I just want to hook up the DC motor to run along with everything else.  I've got some code for a button switch that could turn the motion sensor on and off when I want to use it also, if you know how to set that up that would help. I'm new to Arduino and circuits please help.  Here is the code I'm using: int ledPin = 13;                 int inputPin = 2;                int pirState = LOW;              int val = 0;                    int pinSpeaker = 10;           boolean on = true; void setup() {   pinMode(ledPin, OUTPUT);      // declare LED as output   pinMode(inputPin, INPUT);     // declare sensor as input   pinMode(pinSpeaker, OUTPUT);   pinMode(3,INPUT);   Serial.begin(9600); } void loop() {   //button code for turning on and off the PIR //  if (on == false) { //    if (digitalRead(3) == HIGH) { //      on = true; //      Serial.println("turned on"); //    } //    return; //  } //  //  if (on == true) { //    if (digitalRead(3) == HIGH) { //      on = false; //      Serial.println("turned off"); //    } //  }     val = digitalRead(inputPin);  // read input value   if (val == HIGH) {            // check if the input is HIGH     digitalWrite(ledPin, HIGH);  // turn LED ON     playTone(300, 160);     delay(150);         if (pirState == LOW) {       // we have just turned on       Serial.println("Motion detected!");       // We only want to print on the output change, not state       pirState = HIGH;     }   } else {       digitalWrite(ledPin, LOW); // turn LED OFF       playTone(0, 0);       delay(300);          if (pirState == HIGH){       // we have just turned off       Serial.println("Motion ended!");       // We only want to print on the output change, not state       pirState = LOW;     }   } } // duration in mSecs, frequency in hertz void playTone(long duration, int freq) {     duration *= 1000;     int period = (1.0 / freq) * 1000000;     long elapsed_time = 0;     while (elapsed_time < duration) {         digitalWrite(pinSpeaker,HIGH);         delayMicroseconds(period / 2);         digitalWrite(pinSpeaker, LOW);         delayMicroseconds(period / 2);         elapsed_time += (period);     } }     

Question by TianL4   |  last reply


How to convert a mains from a Catit Drinking Fountain Circulating Pump to a battery system?

Hi All I look after some feral cats and I am trying to improve their health by encouraging them to drink more water by putting a cat drinking fountain  close to their colony. Cats are known to develop kidny problems because of their refusal to drink stagnate water. They see stagnate water as a potential poison. The fountain is powered by mains as per the link below. I was wondering if someone here with good electrical knowledge could pointing me out in the right direction to get this project started. Ideally I would like to get it powered by a battery powerful enough to last a few months or more. I have heard of inverters, but I am not sure if this is the solution. It has to be some sort of standalone mini power plant, because it will live the wild. The power adater is similar to the one in the link below: https://www.amazon.com/dp/B0017VXNVY/ref=psdc_2975263011_t3_B01AKN15KA This is a humanistic project, and I would be grateful if someone could help me finding the solution for this matter. Thank you. A

Question by Alienontherun   |  last reply


Looking for help making a simple on/delay/off circuit.I? Answered

I am looking for help making a ( hopefully simple ) circuit to drive an electronic relief valve. What I have is a push button on a linkage and an electronically actuated valve. I'd like a circuit that, when the button is pressed, will supply a 12v output for roughly 500ms immediately after the button is pressed, which will then turn off. The circuit must then remain off while the button remains held, until it is released and hit again.  Linkage open / Valve closed > Linkage closed / Button pressed > Valve open 500ms > Valve closed / linkage remains closed > Repeat The system is for a turbocharged diesel engine. When the throttle is snapped shut, the boost pressure has nowhere to go. It tries to run back out the compressor housing. This results in a forceful drop in turbine RPM, and in extreme cases even completely stalling the turbine ( and blowing it to pieces ) I intend to vent this pressure back pre-turbo via a 2 inch valve. The short delay upon closing the throttle with this size of valve should be more than adequate. I also intend on wiring a boost pressure switch to disengage this circuit below 15psi. The turbo's anti-surge housing is effective at the lower pressure. Any help with the circuit would be GREATLY appreciated! 

Question by jacob5680   |  last reply


I HAVE A VIRUS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Answered

OK i start google chrome on my Ubuntu operating system and It says: Whoa! google chrome Has crashed Relaunch now? That is not normal if it had really crashed it would say something like: Google Chrome Has encountered an error and needs to close sorry for any inconvenience. How can i Delete this VIRUS? In addition to that, This window Pops-up about 200 Times and there all dancing on your screen. (VERY ANNOYING) 

Question by highvoltageguy   |  last reply


Portable 3.3v regulator for a 9 volt battery? Answered

I've seen a great deal of portable breadboard PSU's that output 5 volts from a 9 volt battery, and I find these fantastic! However, I was curious...is there any way to refine this futher down to get a steady 3.3 volts? I would like it to be something close to the system that sath02 has made here as it not only better suites my nees, but makes sense to me. Thanks in advance!

Question by DoctorWoo   |  last reply


How to wire 2 two-way switches in series to make a 2-way switch system!?

Hey all, my teacher posed this question as extra credit and I've asked quite a few people and no one can figure it out.  The problem is: Use two 2-way switches to create a two-way-switch-system.  When I say 2-way swithces  I mean a switch with two copper screws.  Logically, it can't be done as both switches would need to be on for the circuit to work (power the bulb, that is) but a two way switch system means that either switch should be able to turn on the bulb.  This can easily be solved using two 3-way switches (one black screw and 2 copper screws) but this problem can only be solved using two 2-way switches, power, and the bulb.  I've drawn a bunch of schematics and I've gotten the closes to answering it.  So far, the closest thing I've had is to wire the switches in series but the circuit in parallel.  The answer to this is something so ludicrous that you just wouldn't do it, but there IS in fact a solution.  Please help! Email me at some114@gmail.com (please include pictures if you are able to! I'm uploading a link to a site with all my schematics. link doesn't quite work yet; I'll have it up by 12:30 pm pacific time. http://students.washington.edu/coreyg3/help/help.html

Question by some114   |  last reply


How can I pass voltage through a wire only when it goes over 7 volts? Answered

I'm trying to hook up a Z-Wave contact sensor to my home alarms wired contact sensor. The alarm panel seems to provide a constant voltage of 6.8 when the door contact is closed and 13.5 when it opens.  The z-wave module I am connecting however looks for no voltage in order for it to be closed and any voltage for it to be open. So how can I only pass the voltage to the z-wave sensor when it goes over 6.8 volts? I have a ground and power wire running to the respective terminals on my alarm panel. I'm thinking I may be able to wire in a resistor but am not sure if that is what I need or what size. Thank you

Question by Mweston011   |  last reply


Underground Tube Air Conditioning

I have long heard about using buried tubes/pipes to use as a heat exchanger to take the hottter air from your house, blow it through a system of closed loop underground pipes in order to use the earth mass as a heat exchanger. The earth mass removes/absorbes heat from the house air in the pipes and delivers cooled air back into the house. Can anyone direct me to web sites about this subject. Or, certainly, if you have knowledge about this, reply to me with it? Thank you, John333

Question by john333   |  last reply


How to design and build a switchable 3 colour LED into a 4x4 (16 cube) shelving system? Answered

Hi all, I've been wrecking my head on this project that I want to make, and I just can't seem to nail it, so hope some of you guys and gurus with much more electronic experience might be able to give me a nudge (or tell me that this is going to be borderline mental). Background: I repair laptops and wish to make a lighting system to give a visual indication of my current work flow. If a new laptop is placed in one of the 16 shelving cubes, I want to hit a switch on that cube to indicate the colour (RED), to say its a new arrival and hasn't been worked on yet. After getting it on the bench for assessment, it will be returned to the cube in one of two forms, either A) Its unfinished and awaiting parts/customer communication (hit switch and show BLUE LED) or B) Its finished and ready for collection (hit switch and show GREEN LED). The only thing close to an off the shelf (no pun intended) product that I've been able to find is 31cm wide Aquarium overhead LED for fish tanks. These come in at £11 GBP each, and I need 16 of the guys... so £176 to begin with as well as the issue with each unit having its own 12v Power Supply that needs plugged in! (Ouch). So, can someone here possibly recommend a solution to this that A) Isn't going to cost me my first born child and B) Not use up every plug in the house! :D I will admit, I'm actually not entirely averse to buying the 31cm bars as above, but would definitely need to be able to address the power requirements safely. I'm really looking forward to your ideas or certainly if you know of any other off the shelf (still no pun intended) product that I could modify to fulfil my needs.

Question by sheasmith   |  last reply


How can I turn a tablet pc into a universal remote control?

I am interested in turning an old tablet pc into a universal remote control for my entertainment system. I would need to build a transmitter compatible with the computer and have a program that could allow it to give the right frequency to be used with a tv. I have looked online and the only things even close to this use 9-pin serial ports. This computer does not have any. Is there another way? If not would you be specific in the circuit needed to be built, I am not very good with circuits.

Question by gryffin13   |  last reply


Automated dimming LED Aquarium light with moonlights? Answered

How do I make a Aquarium light that is automated simulating dawn and dusk, then turn on/off moonlights using LEDs? I want the system to be based upon time. The array of LEDs for daytime use can slowly 'awaken' over the course of an hour then the after a specified length of time, the daylights slowly turn off then start to slowly turn on moonlights. I saw an instructable that showed how to mimic the outside lighting to replicate that in the tank but I don't have my aquarium that close to a window so I'd rather it be based upon a programmable clock.

Question by seadweller43   |  last reply


PIR alarm somehow works WITHOUT PIR attached

So I was playing around with this instructable: https://www.instructables.com/id/DIY-Motion-Sensor-Alarm-System/ and it works great, I made it on a bread board and when I unplugged the PIR to switch a jumper, I noticed that the LED started acting as a sensor! That is, when I got close to the bread board, the LED would light up and the alarm would go off, it would stop when I moved my hand away and start again when I put my hand back... This may be a stupid question, but I am really curious how this works!

Topic by emikayee   |  last reply


pump capacity / electrical interference

I am building a custom watercooling system in a confined space, with the pump motor close to the processor. for the pump, I intend to use a thin centrifugal pump with a centeral brushless motor based around a re-wound cd drive stator, but don't know what the power required to move enough water is, especially with small bore pipe (2 X 1/4" also, when positioning the pump, how far away should it be from the main board to avoid causing interference, as the pump is essentially a large spinning magnet with several amps going to it. I'm guessing the motor should be as far away as possible, as well as the supply cables. thanks for the help.

Topic by The Skinnerz   |  last reply


heat isolation, how to keep heat away from electrical cords? Answered

 hi, we're building our own heating system. we're using ventilation tubes(often used on dryers) to distribute hot air through the shed, but it needs to get pretty close to an electrical cord(+/-1 inch) and the tube gets pretty hot(at least 200 degrees Fahrenheit). which is a bit of a problem, the electrical cor is the type you'd burry in the ground, and it looks like it shouldn't melt too fast, but we still ant to isolate it, any hints/tips on what kind of material to use would be appreciated... 

Question by lieuwe   |  last reply


Arduino Outdoor Security System - PIR Motion Sensor, Security Lights, Intruder Warning/Alarm & Blynk Notification

I would like to ask your suggestions on how to build an outdoor ESP2866 security and sensors combo. I have seen separate postings on PIR and lights around the site and in other websites so I thought it would be doable. I knew Arduino then but only paid close attention when I realized that my x-10s are outmoded but z-wave devices are expensive. So I am learning about it, how to sketch and trying to understand C++ more. My dream is to build an outdoor ESP2866 combo, powered by an AC120v-5v module, with two PIR motion sensors, three 120v relay switches (two relays for two sets of security floodlights and one relay for an amp/wave speaker with mic), a photo (dusk/dawn) sensor and temperature/humidity sensor (for a future thermostat). Operationally, I imagine that it could be armed and disarmed through Blynk. When armed at daytime, a motion will trigger a low volume intruder MP3 warning alert with 10 minutes of security lights at night. But if the trigger persists for more than 5 minutes, the security floodlights will blink, a loud intruder alarm will sound and push phone notifications. What will be the best way to sketch these? What is the better way of wiring them together? How could I make multiple ESP2866s in the same WAN work together for an event? The desired function is if an alarm event is triggered in one of the ESP2866 that would also set off blinking lights and alarm sounds in the other ESPs. Thanks for all your help.

Topic by EeA2   |  last reply


A Hybrid of Coil and Rail gun

So I said i'd throw this up in the comments section on Youtube not too long ago, and I don't like it when something easy and free doesn't happen. This is some ideas and observations that have to do with coil guns (mostly). I'm in the process of finishing up several projects, so my resources are kinda spread out. I should have a prototyped coil gun finished in 2-3 weeks though, so if this doesn't clear things up, hopefully that video will. I should point out, I am a chemist with expertise in biochemistry, not electrical engineering. Basically my idea is to combine a railgun and a coil gun for the expressed purpose of avoiding the pitfalls that a pure coilgun or a pure rail gun have. At present, none of the designs out there would be capable of competing with an actual gun. By mixing the two, i'm hoping to get something that might eventually be capable of doing so. So.. I've included a very poor drawing (I'm not an artist). The barebones circuit is sketched in the lower right hand corner. The gun barrel, which is a piece of aluminum tubing split into two pieces to sever as a rail system, is sketched in the upper left, and again in the middle figure to show how to integrate the coil and rail system. Looking at the circuit design, you can see that this starts off as a very basic capacitor-inductor circuit. The charge is purposefully allowed to trickle through the circuit until the coil reaches saturation and the capacitor(s) are charged. When the trigger is pushed, the inductor side of the circuit has to dump into the rail system to complete the full closed loop. Because of the ferromagnetic material (the brown stuff), the magnetic force persists for a while (that is to say, it has high reluctance). The ferromagnetic material does one other thing that is important here. It forces the middle of the coil to be far off center. The coil is pulling the projectile into the middle of the magnetic field, but that is not necessarily in the center of the winding. Adding ferrite, or other high reluctance material, towards the end of the barrel biases the field towards that end.  At the same time that the coil stops getting current, the rail system become active. This allows a charge to pass through the bullet/projectile, and, even though the majority of the force is going to be caused by the inductive coil, the rail system allows an eddy current to setup in the bullet. This does several things. First the bullet doesn't have to be iron, nickel, or cobalt. With a stray eddy current in the projectile, any conductive material will work. The advantage here is that once the current stops, the non-magnetic material stops being  to the magnetic field, preventing backwards acceleration of the projectile as it exits the barrel.  Second, Rail systems and coil systems are not often used because they are perpendicular to one another, but, this can be used to put spin on the projectile, in a similar manner to rifling in a barrel.  After the projectile is fired, the circuit is open, preventing excessive electrical discharge.  My circuit design is really badly drawn... =T if it needs more explanation please post up questions. 

Topic by Qcks   |  last reply


How can I make a single LED lite which can be placed in windows of a remote house to appear as security system in place.

We have a remote house under construction.  I've been trying to find a way to have a tiny LED installed in the inside part of the window frames to appear that an alarm system is in place.  We have cameras in place but this would be just another layer for the crook to decide if he wants to go further. The house is closed in and dry.  There is 120v available.  If it is possible, I'd like to have a "socket" at each location for bulb replacement.  It can be low voltage with a transformer and it would be better if all the lights were on the same loop.  The loop would be about 100' and 8 windows. If the only way is a individual LED powered by some tiny battery, that could be OK if the life is quite long. I could fabricate a housing to hide the battery or socket so only the light appears. I'm also trying to figure out how to making a single flash LED which I will post as another question in the same category. Thanks very much, GTinWA

Question by GTinWA   |  last reply


Is it possible to make an iphone/android app that runs full windows 7?

Is it possible to make such an app that detects all the phone's hardware and runs it at full speed (the app should not emulate hardware)? This app would need to recognize the touch screen as a touch input interface (not an emulated mouse). When the app starts up, it should close out all other system tasks and dedicate the system resources to the app so it can get the maximum amount of RAM/CPU. Also, the OS would probably need to run off a hard disk image file on a 16GB/32GB SD card. If possible, a network interface through 3G/WiFi would be great. Before you say that windows 7 is in x86/x64 architecture and doesn't support ARM architecture, that is another thing this app should accomplish. I noticed that the windows 7 system requirements were a 1GHz processor, 1GB of RAM, and at least . Phones meet those requirements. PS: Right now I am running windows 95 under a QEMU app on my android phone and it runs extremely slow since the whole PC is being emulated (and my phone is only 800MHz and has not all that much RAM). I've tried to run ubuntu on my phone (android is linux based). It worked perfectly, but due to not enough free RAM and the 800MHz CPU, it was very slow (but not as slow as emulated windows!). On a 1Ghz phone, ubuntu appears to run perfectly. If you can come up with an app like this (or find one on google), please post a download link to the site/download link. Thanks, Absol32

Question by epicnoobpwn   |  last reply


EcoDimmer: New hardwired/DC LED lighting for DIYs

Hello everyone,My name is Mark Gilmore, and I am the owner/president of Omnipotence Software.We have been developing automation software since 1990, our primary product being "ECS"(http://OmnipotenceSoftware.com/wpr.htm).We have been closely following the trend towards LED lighting for a few years now.But when we looked for systems that could be automated, we found a void in the market.So we decided to make our own:Our "EcoDimmer" controls up to 16 low-wattage (DC) lights or appliances with push-buttons,keypads, and/or automation software (like ECS).To our knowledge, this is the only direct-wired/DC lighting system that can be automated.The EcoDimmer is intended for installers and DIYs.It does not include buttons, lighting, or the dimmer's power supply, as these will varygreatly for different applications. So with the exception of the optional/pre-installed keypad,these must be purchased separately and wired to the unit. But as only 2 connections are required for each, anyone can perform this task with a screwdriver and a knife. For further details, please see http://OmnipotenceSoftware.com/wpe.htm.We welcome any feedback (esp as this is a new product) !Regards,Mark Gilmoresupport@OmnipotenceSoftware.com

Topic by MarkGilmore 


Why does my PICAXE 08m seem to be resetting itself half way through the program?

I am at the final stage of my automated chook door project, and have come across a problem which is proving a real headache. To begin explaning the problem first of all I must explain a bit about how it works. First of all a PICAXE 08M is used to control a linear actuator attached to a vertical sliding door. The PICAXE is fed an LDR (light reading) and based on this 'light level' is programmed to either raise or lower the door. Two relays are employed to operate the actuator in one direction and then to reverse it (that is turning ouput 1 on lowers the door, turning both output 1 & 2 on raises the door). Unfortunately I don't have any position sensors built in (something which I now realise I should have done), which means that I have to operate the door for a set period of time (meaning that the program assumes where the door is at). Anyway when it is day I want the door to raise in order to let the chooks out. First it checks through regular intervals (and I will extend these intervals when I know its operating correctly) whether it is a certain light condition, then a pause occurs aswell as another light check to ensure that it is acutally the right light level, ready to open the door. The same also occurs when the door closes HOWEVER there is a safety system fitted to the bottom of the door (an aluminum bar which is spring loaded and hangs bolow the physical door. It is hooked up to two microswitches in series which provides input to the PICAXE). It is designed to provide feedback to the PICAXE in regards to detecting an obstruction. Because this model of PICAXE 08M does not support the SETINT command, I cannot detect a obstruction while the program is paused for the duration of the doors travel to the closed position. This lead me to try and develop some code to beat the situation. ( By the way, when an obstruction is encountered the unit is programmed to raise the door for the equivalent of 4 loops worth of door travel, and then return to the closing sub to continue closing the door. If 5 or more obstructions are encountered the program ends requiring the user to remove te obstruction and reset the unit.) As seen in the code, I broke the time required to close the door into 250 ms intervals, and then created a for loop which performs each interval seperately. I did this so that within each loop (and therefore within each 250 ms interval) I could conduct a check to see if an obstruction had occurred before a certain loop number (NOTE I'm using Normally Closed microswitches: If input3 = 0 and Position < 83 then). The reason I have to test that the obstruction is within a certain loop number is so that the program will only accept an obstruction input while the safety bar has not reached the door frame - otherwise the PICAXE will think the bottom of the door frame is an obstruction and will continually raise and lower until the program ends after 5 obstructions - when in fact there were none! In theory and using the BASIC program simulator, my program works fine, however in reality it doesn't! The door raises fine and lowers to the closed position as desired (only when there were no obstructions! - in other words the safety microswitches were never activated). Unfortunately as soon as I introduce an obstrucion when the door is closing, it raises correctly and begins traveling to the closed position as I would hope. However when the door reaches the bottom it begins a continous cycle of raising and lowering (as would be valid if it were an actual obstruction). It has baffeled me for almost 2 days now, and the way that its behaving seems as if it reseting itself somehow. I am thinking this as I know that the program continues to raise and lower the door even after 5 obstructions (which would work if it was reseting as the obstruction variable would be reset to 0 everytime) have occured. If this part was at least working it would kill itself after 5 obstructions, however it just keeps going. To me it seems that when there is an obstruction and it reverses the door, a reset occurs, beginning the full door closing process. But because the door has already lowered a little the program then beleives that the bottom of the door frame is an obstruction and hence is in an evil loop of door raising and lowering. Can anybody please offer some adivce on my problem? I have tried replacing the PICAXE chip but the same problem occurs. The underlying issue I think sits at the level of trying to match the physical door location with the virtual location, based on time. HELP would be greatly appreciated! CODE: 'NOTE: Not all comments may be correct Load: symbol RELAY1 = 1     'Initialise Relay1 to output 1 symbol RELAY2 = 2     'Initialise Relay2 to output 2 symbol SETIME = 26500 'Initialise the SETIME variable to 26.5 seconds symbol LIGHT = b0     'Initialise current LIGHT variable symbol DAY = b1       'Initialise DAY light variable symbol NIGHT = b2     'Initialise NIGHT light variable symbol POSITION = b4   'Initialise counter variable symbol STARTPOS = b3 symbol OBSCOUNTER = b5' DAY = 100    ' Set Day threshold equal to 100 NIGHT = 30   ' Set NIGHT light threshold equal to 30 CheckLight: '**************Check Light**************** Readadc 4, LIGHT       'Read in input4 (LDR) and store in LIGHT variable If LIGHT > DAY then    'Check if current light level is > than the day light threshold   Goto CheckDayAgain   'If condition is true go to the CheckDayAgain sub Endif If LIGHT < NIGHT then  'Check if current LIGHT level is less than the NIGHT light threshold   Goto CheckNightAgain 'If condition is true goto the CheckNightAgain sub End if 'Pause 60000           'Pause 10 seconds Goto CheckLight        'Recheck light level CheckDayAgain:'*********Check Day Light Again********* 'Pause 10000 Readadc 4, LIGHT       'Read in input4 (LDR) and store in LIGHT variable If LIGHT > DAY then    'Check again if current light level is > than the day light threshold    If input3 = 0  then     'Check if switches are open indicating door is closed (as micro switches are normally closed)       Goto OpenDoor    'If Light > day light threshold and door is closed, then go to OpenDoor sub    End if End if Goto CheckLight        'If either of the above conditions are not true, then return to CheckLight sub CheckNightAgain:'*******Check Night Light Again******* Pause 1000 Readadc 4, LIGHT       'Read in input4 (LDR) and store in LIGHT variable If LIGHT < NIGHT then  'Check if LIGHT is < than the night light threshold   If input3 = 1  then  'Check if switches are closed indicating door is open (as micro switches are normally closed)       Goto CloseDoor   'If Light < day light threshold and door is open, then go to CloseDoor sub   End if End if Goto CheckLight        'If either of the above conditions are not true, then return to CheckLight sub OpenDoor:'***************Open Door******************* High RELAY1            'Switch on relay 1 or output 1 High RELAY2            'Switch on relay 2 or output 2 Pause SETIME           'Pause 26.5 seconds to allow door to rise Low RELAY1            'Switch off relay 1 or output 1 Low RELAY2             'Switch off relay 2 or output 2 Goto CheckLight        'After opening door go back to CheckLight sub CloseDoor:'**************Close Door****************** High RELAY1                 'Switch on RElAY1 to close door For POSITION = STARTPOS to 93         'Enter a for loop representing the time needed to close the door   PAUSE 250                'Pause 250 milliseconds for each loop   If input3 = 0 and POSITION < 83 then'If switches are closed and safety bar has not reached the bottom then an obstruction has occured     Pause 10                'Pause 10 milliseconds to allow for switch bounce     If input3 = 0 then                'Check if switches are still closed      Gosub Obstruction      'Go to obstruction sub when switches are closed and door is not fully closed     End if   End if Next Low RELAY1                 'Switch off relay 1 or output 1 STARTPOS = 0 Goto CheckLight          'After closing door go back to CheckLight sub Obstruction: OBSCOUNTER = OBSCOUNTER + 1 'Add 1 to the obstruction counter High RELAY2                 'Activate second relay to reverse door Pause 1130                  'Pause 1010 ms. The extra 10 ms is to account for the swith bounce delay Low RELAY2                  'Deactivate seconds relay to allow door to continue travelling down If OBSCOUNTER > 4 then      'if there are 5 or more obstructions then shutdown unit. Goto Shutdown End if If POSITION > 4 then        'Prevents a negative POSITION STARTPOS = POSITION - 5     'Minus 5 is to account for the fact that program returns to the next statement before executing another loop. End if Return                      'Return back to the loop to try finish closing the door Shutdown:                   'This sub raises the door slighty before killing the program. The user is required to clear the obstruction and reset the unit. High RELAY2 Pause 1000 Low RELAY2 Low RELAY1 End

Question by Mattdog123   |  last reply


Too big enclosure for sub woofer?

Last year had a lot of bad luck making my bike sound system. I made some boxes, fried some electronics, etc. The boxes were too big for easy handling, so I'll make another attempt, since spring is coming. I noticed the speaker (driver) did not like higher volumes; very large excursions in the lower Hz range , probably hitting the end of its moving range. It is a closed enclosure, no port. The RMS output of the amp is probably many times lower than the RMS rating of the speaker (driver); logitech 2.1 computer amp with consumer grade sub speaker (6"). Same problem occurs with my home 10" 60 W RMS driver in a closed ca. 70 l - ca.15 Gallon barrel, with a modest 25W RMS amp: I cannot even turn it halfway up:  it is mounted horizontally, and shoots peas 40 cm (16") up! Would it be more helpful to make the box / barrel less square? Like halve the size by putting a diagonal separator in the box? Or is geometry irrelevant and does only volume matter? Perhaps there even might be a formula????

Question by BobS 


Needle valve on the cheap?

I need a needle valve or similar to adjust some pressure with more or less precision. Problems I am facing with commercial solutions at the moment: Needs to withstand about 300psi max pressure, must survive contionous exposure to concentrated ammonia vapour. I already wasted too much money on stainless steel valves claiming to be chemical proof and capable of 6000psi only to find out they use seals that turn to goo in the ammonia vapour and fail. And since the stuff is not really healthy, not easy to get, I would prefer something safer. Real problem is also that the thing should be able to allow for good flow rates when opened fully. Modes of operation: During the active cycle ammonia vapour needs to pass through an opening as big as possible while after that the flow must be shut off. The reverse cycle needs to be adjustable from closed to fully open with great detail to control the flow rate. Current ways to compensate: With a ball valves and extra piping I could seperate the two cycles so I won't have to bother with tiny openings but I would prefer to use only a single connection. With a bypass around the needle valve this could be accomplished better but still looks ugly. Materials out of the question: Copper, brass, normal seals based on rubber, nitrile or similar. Questions: I know fully sealed in.line valves exist for LPG system and similar. Are any of these magnetic valves available for the use with ammonia? And if so: Can they be operated with a neodymium magnet instead of the coil? Even stainless steel valves rated for chemical use and high pressure fail quickly on the seals. Is there anything available that does not use soft seals but for example aluminium instead? Thinking spray pump here... One way ball valve systems like used in simple spray pumps are a great thing. With some aluminium tubing I was able to make a simple valve that with some more attention to detail might even work. But of course there no other way of moving the ball then to use a magnet and with sufficient back pressure even neodymium ones fail to get the ball in the open position and keep it there. Now getting this combine with a needle... If, instead of the ball, a magnet in a teflon shell is used on a spindle I could spin a magnet around the outside to turn the valve with great precision. Has anyone already designed such a thing or would I have to start from scratch here?

Question by Downunder35m   |  last reply


Wiring a salvaged CD drive eject tray mechanism and motor into a car?

Hi everyone. I'm making a custom back-up camera monitor mount for my brother's car. He doesn't live in a great neighborhood, so we want it to be hidden when not in use. We were just going to conceal it in an unused cubbyhole drawer under the radio, and he could pull it out and push it back in as needed. But as I was sitting at my PC, I bumped the DVD eject button and it occurred to me that we could spend a little more effort and have it be powered using a salvaged CD drive. I'm not an electronics guy, but I've pulled apart an old CD drive and the motor and gearing system seem fairly straight forward. The car is 12v DC, obviously, and the eject tray motor is also DC, but the spec. sticker on the motor is unreadable, so I don't know the voltage.  There's an obvious limiter switch in the mount that flips when the tray is fully extended, and what looks to be another one on the circuit board that flips when it's closed. Can anyone help me with wiring on this? I'd like to have it so he either presses a concealed switch to open and close the drawer, or possibly have it tie into the switch that activates the back-up lights. Thanks!

Question by drkillbot   |  last reply


key-less entry / key-less ignition (arduino based)

Hey guys, I want to make a key-less ignition and a key-less entry on my car. I have no doubt that arduino can be the core for this system. as of now, I am thinking of using arduino UNO to control everything and an RFID unit for the key-less entry. I know that there are many types of RFID, some for sensing close like tags or cards, and some for larger distance like 10 to 20 ft. the one I need will have to be able to read a module from around ten feet of the vehicle. I am debating whether to automatically unlock the vehicle when the module is within range or put a button on the door handle and trunk so that they will unlock if the key is in range. I decided that the push button ignition will include a toggle for ignition and a push button for start. The ignition switch will be wired through a relay so that the arduino can "enable" ignition when the key is present. I want all redundant systems so I will wire the ignition in parallel so the stock key will still start and run the car. I post this for advice, comments, and any improvements you guys can think of. My budget is $200 maximum. My goal is to make it for under $150. Any help would much appreciated. - Jordan

Question by gen.badger   |  last reply


PICAXE Ciruit Help needed! I'm trying to figure out why my circiut is not working. Can anyone help? Answered

Note: I have attached a copy of my programming and the schematic of the circuit. As part of my school systems engineering course, I have decided to build an automated chook shed door. For the electronic side of this project i'm using a PICAXE microprocessor (PICAXE 08M - to be exact) to control the up and down operation of the door - which is done using a 12 volt linear actuator, all powered by a 12 volt battery (eventually to be rechagred by a solar panel). My theory is to basically read in the light level using an LDR and then based on this level to open the door, or close it. The is designed to work through the use of 3 relays (all with built in diode protection). The first relay is connected to the 12 volt power which supllies power to the other set of relays, and in effect the actuator, when ouput 0 is turned to high (I'm using transistors to do this as seen on the in the shematic). When I want to reverse the the motor I again turn ouput 0 to high, but also ouput 1 to high which switches the the other coupled relays (again using a tranistor) and in effect the polarities of the actuator.I'm also using two microswitchs on the bottom of the vertical sliding door as a safety mechanism, so that when the door is closing and an obstuction occurs (i.e a hand or piece of wood), its programmed to lift the door for about a second before trying to close again.  As mentioned before it acts a safety mechanism so that no little fingers can be chopped off, and the actuator it self doesn't overload and blow up (although I'm pretty sure it has inbuilt protection for this anyway). Ok anyway to the problem, I have wired everything up as to the schematic I have provided, and loaded the program onto the chip (which it does successfully do) - however its not performing as desired. I have placed the same program onto another identical PICAXE system (except it is not obviously connected to all of the stuff mine is) and it works fine. I have also tried reducing the complexity of the program and taking out the LDR readings in the code, and when I do this,  it does successfully turn on the relays as desired. For some reason it appears that the LDR is reading a full light level even when I place my finger over it, and because the IF statment in the program relies on a low LDR to operate, the code which turns on the relays never gets to execute.  At first it seems that there may have been a problem with the LDR, so I changed it  with a new one, but again it continues to read the highest value of 255 (or 1 byte) and therefore the program never executes as desired. I'm not sure why the LDR keeps reading the highest value. CAN ANYONE HELP!

Question by Mattdog123   |  last reply


Best practical way of making biochar for soil improvement on commercial scale?

I need help to build a cost effective biochar retort that will produce at least 500 kg biochar/day to use for soil improvement on my dairy farm. It must also be moveable to move to new sites. I've got access to a lot of forestry waste all over the district. Here is my initial idea: From 3mm sheet metal manufacture cylinders (drums of say 200 lt) one bigger than the other so that one fits into the other with a 100 mm play all round. Bigger cylinder has a lid with a chimney on top and close ended at the bottom with air inlet holes around the base and completely isolated with fire proof material. Smaller cylinder (that goes inside) is open ended and stand on bigger cylinder baseplate with airtight lid that gets closed after filling with wood chips. It has 50mm outlet at the top that connects to a metal pipe (coming through the side of the outer cylinder) that leads woodgas to the bottom of the next retort and maybe have a drain to catch bio oil. The idea being that I can duplicate the retorts to increase production using woodgas from the previous to pyrolize the next. I then only have to burn wood in the first retort to get the process started. Please suggest improvements, or complete new more viable system. What can I use for isolation material? Can I collect other products off the woodgas instead of pyrolising the next batch?  What other byproducts might be valuable?

Question by HMST   |  last reply


Need Help With Wiring Up Two Limit Switches?

I have a closure system with deadbolts that works on a sliding assembly with a solenoid that turns 180-deg to close and the other 180-deg to open. It is accomplished with two limit switches (as shown in the picture attached). My question is I have a single control button. If I press it once -- I need it to trigger the power in conjunction with one of the limit switches (to stop the solenoid at the appropriate time) and then on the next press of the button, send power through the other limit switch so it cuts power at the appropriate time. Obviously if I wire everything at once you have one switch open when the other closes and vice versa so power continues. My question is this. I believe I can use a 4017 chip to allow power to go to one and then the next with each press of the button. However it seems like overkill and I figure that there has to be a simple one-two power diverter switch of some kind that I can put between the button and the solenoid/limit switches so it cycles between the two. In other words. When power comes through it the first time, it routes it into limit switch #1, the next power cycle goes through to limit switch #2, and back and forth. Is there something simple like that. If so please share. If not, can someone please tell me the best way to wire up a 4017 chip for this purpose. As always, thanks in advance for any experience, advice and/or wisdom -- it is greatly appreciated.

Question by pletchman   |  last reply


Speaker (single) Volume Control

I have a Panasonic home theatre system, standard set up. ( 2 front, 2 rear,1 centre and 1 Sub woofer). Unfortunately, because of the room layout, I'm not able to site any of the speakers in an ideal location. So, I have to make do with the best poss. One of the rear speakers is close to where I sit, the other 3mtrs diagonally opposite. I want to insert some form of volume control into the feed of the adjacent speaker. So that when set the rear speaker volume level there is a better balance between the near and distant speaker. I am unable to access any other wiring or components apart from the speaker feed wire, so it has to be something in line. I tried a dimmer switch (dont laugh) but that attenuated the signal too much, and was barely audible. The speaker is 6 ohm imp and 60wat power input. Any suggestions appreciated, apart from buying a new house!

Question by rogedodge   |  last reply


Using Arduino to control circuit to LED strip

Hey guys! First forum post here.I am currently trying to design an LED light system where when I place my wallet onto an NFC reader the lights turn on in my room.I am using an Arduino Uno for this project and I am stumped on how I do it.I have a separate DC Controller and a 12v, 3A battery to power the LED strips. I just want to use the Uno and NFC reader to either open or close the circuit. I don't want to pass the amperage through the Uno as it will just fry the board.Is there any way I can control the flow of the circuit without having the power pass through the Uno? I want to keep the power the battery pack supplies and want to make sure I won't just fry my board.Any help will be appreciated! If you have further questions feel free to ask.

Question by MikoPico   |  last reply


analog circuit to mimic constant resistance load? Answered

I unfortunately do not have many big resistors that can dissipate lots of power, and would like to make a dummy load to test and parameterize batteries and power supplies. I want constant power, constant current, and constant resistance load, I do have lots of opamps and a few N and P channel enhancement mode MOSFETs as well as many 2N3055s and a couple MJE2955's. I think constant current is the easiest, since all I need to do is make a closed loop controller that will turn off the transistor as the current is exceeded, and turn it on as the current falls. Constant power might be more tricky, as I need a device that controls the bias on a transistor as a function of the product of the voltage and current, since P=IE or W=AV, and similarly, constant resistance, I need a thing that will divide voltage across the pass element by the current through it. I don't want to use a "slow" microcontroller for this, I like nice continuous analog control system, if that is possible.

Question by -max-   |  last reply


Temperature and duty cycle controlling PWM help needed! Answered

Hello, I am working on a Hydrogen generation project. I am using a PWM (pulse width modulator) to control the Generator from going into thermal runaway. However, the current PWM's on the market dont offer temperature control. Only duty cycle control. So I need some help here. I need a way to control a potentiometer to increase or decrease resistance based upon a temperature range from 80 to 95 degrees. I dont want this to turn the unit off, only lower the duty cycle when the peak temp is reached. Then also, when the unit is cold on start up, it would release full amps into it until it reached it peak operating temp. The idea is to make a PWM control the generator via duty cycle (amperage draw) and temperature. Make it a "set it, and forget it" system. My thoughts are using two surface mount thermostatic switches. One for low limit the other for the high limit. Then a relay and another potentiaometer. Theory of operation: On initial start up, the generator is offered full amperage draw of 40 amps(100% duty cycle) until it reaches its operating temperature of 80 to 95 degrees. Once it reaches the peak of the operating temp the upper limit switch kicks open causing a relay to offer a differing resistance (80% duty cycle) that would effectively make the PWM still keep producing hydrogen, but cool down. When or if the lower limit of 80 degrees is reached the lower limit thermostat would close allowing again 100% duty cycle to the generator.  Thus, this system would keep the generator operating at an optimal temperature at all times regardless of outside temperature, and conditions. Current PWM's require the user to manually get them set. If the outside temps are colder the system will work less effectively. If the outside temps are hotter the temps may cause thermal runaway. All operating conditions require the user to be constantly fiddling with, and keeping an eye on the amp draw, temps, and voltage. This means eyes not on the road while driving. Bad ju-ju. I'd like to make this device super simple to operate, and build. With off the shelf items, not custom IC's. Any ideas?

Question by ydeardorff   |  last reply


Need help simplifying project (Raspberry Pi + Pi Musicbox + NFC Reader)

Hello.I have a desire to build this project - https://github.com/brendandawes/PlasticPlayer.But I'm a total layman in hardware.TL;DR: Media player based on Raspberry Pi and Pi Musicbox (mopidy), with the Espruino + NFC reader used as a track selector (NFC cards store the track id which is then cross-referenced through a database).Upon close examination I think the additional Espruino is redundant (especially in the way author made it, so it talks to Raspberry via wi-fi), and I would like to connect it directly to Raspberry Pi.I've ordered the Raspberry Pi recently, and it hasn't arrived yet, so I can't really tinker with it. So asking the question ahead.Taking into account that Pi Musicbox will used as the base system, what exactly do I need to do, so that it can control NFC reader?How can I create a program to control Raspberry Pi GPIO? Is it possible to make it compatible with common libraries that are available for NFC reader?Thank you.

Topic by beshur 


Can anybody tell me how to (further) check my VAWT charge controller for malfunctioning?

I have installed a Flexcharge NC25A-12 Charge Controller and an SE440 regulator in line between my VAWT turbine and its rectifier and the 1000 amp inverter. The turbine and controls charge four Trojan 105, six volt, batteries which are hooked in series parallel (two each in parallel, the parallels hooked in series). The turbine is a heavily modified Lenz-2 (vertical axis, three blades with spring-loaded furling & angle of attack control). It generates 108 to 140 Watts (nine amps at twelve volts to ten amps at fourteen volts) at wind speeds of fifteen to twenty five miles per hour. Nevertheless, I'm not able to charge the batteries. I think the Flexcharge charge controller is stuck, that inasmuch as the controller’s "Multi Function Indicator" function does show when batteries are low, when voltage from the system is low, and when charging is occurring (flashing and steady green light), but has never shown "divert" (to a heat sink). More, I have never been able to get the batteries to hold anything close to their individual 225-250 amp-hour rating. It's beginning to look like the batteries, purchased new originally, have sulfated on account of the charge controller panel not working. I note in using my multimeters that the cable at the heat sink indicates 2.85 volts, even when the batteries are down to 11.9 volts, and when the charge controller is not indicating "divert." When, moreover, an external battery charger (the automotive kind) is hooked in line and in lieu of the wind turbine and rectifier (these being disconnected from the controller, regulator, batteries, and dump load), the batteries indicate full charge on both hand-held multimeters and turbine system voltmeter and ammeter, but the charge controller does not indicate “divert” to the dump load heaters. Any ideas will be much appreciated. Thanks!

Question by taiosan 


Hacked Road Signs

This may be one of the greatest pranks I've heard of in a while.We see them everywhere these days, digital signs by the side of the road telling us about road conditions or that we should prepare to stop or that our local bridge might be closed next Tuesday from noon to midnight. And if you're like me, you've always just assumed that the message on the signs is legitimate and properly authorized.But what if the sign, instead of reading something like "Ice Ahead" was flashing the message, "Zombies Ahead"?It's true that in San Francisco or a few other cities, such a sign could be put up by local transportation officials to warn people of an impending zombie march, but even in those places, the more likely explanation would be that the sign was hacked.And if you're in the Boston area and saw signs hacked in this way, there's always a decent chance it was done by students from MIT.According to the blog i-hacked.com, some programmable road signs are easily messed with, largely because they often have unlocked instrument panels, a text-entry system that is easily accessed, and are often protected with uncomplicated, or unchanged default passwords. That's some of the text from an article on cnet, here. I love what the hackers did with the text. :-)

Topic by Gjdj3   |  last reply


DIY Infrared range disappointing, TV left wanting more...

I have constructed what I like to call a circuit...and maybe therein lies the problem. The folks over at IRdroid.com have been gracious enough to post the schematic to the hardware that they also sell in the store. I have followed this as close as I could, however I have gone astray in 3 areas. PROBLEM The unit works, my television turns off/on but only if I am within 3ft from it. The IRdroid.com website states that their device works at over 10 meters (18+ miles right?...I'm kidding, just a little Imperial system humor). 3 known differences 1. R5 calls for 1k2, I don't have one...I used a 1k and a 330 in series. 2. C4 and C5 call for 10uF, I used 10uF for both. However, one of them is 16v and the other is 50v. 3. I don't have a 6v battery, so I have tried 5v, 9v, and 12v with the same results in each case. Would any of these 3 mistakes cause my range to be 10x less than the site claims? 

Question by earthtown   |  last reply


Treadmill Motor Control

I have a Horizon T101-04 treadmill that has a control problem. The motor is definitely good. I suspect that the motor control board is good, and the control panel board is bad. The control will not reset or go into diagnostic mode. I want to replace either the control panel board or the entire control system. The motor is 90V DC. For amperage, the motor label says "19A S6 25%" which has no meaning that I understand, other than perhaps that the maximum amperage is 19. The label says "APMS" rather than "AMPS", and I wonder if the "S6" is supposed to be "SC" for "stall current." All of the characters on the label are very legible. To replace the entire set of controls, I can use an industrial DC motor control, but how much horsepower does the control actually need to be able to provide? I don't think that the one on the treadmill actually provides 19A, and is probably close to 1 HP or so in its capability.  To replace the control panel with something else and keep the existing motor control, what do I need? Do I need some type of complex driver circuit? Does it need feed back from tach sensor to do a good job of keeping the speed steady?  If it will work well, I want a simple control set up like a KB Electronics KBMD-240D to which I will add a safety cut-off switch with a lanyard.

Topic by Ineedacircuit   |  last reply


weird PC power problem? Answered

Hi, I'm experiencing a weird problem with my PC. recently (about 2 months ago) i have upgraded my video card to a Sapphire 7970 and about 2 weeks ago installed a second monitor to my system (dual D2342P , added one first, bought new desk, added second one). in the past 2 weeks i have had no problems at all. in the past 2 DAYS my PC has randomly shutdown abut 6 times (most recent 1hr before this was posted). the first few were relatively close together, about 2 - 4 hr apart. the most recent ones have been almost exactly 12 hrs apart. (~11 am - ~11pm) . yesterday (Monday) i replaced all 7 case fans and cleaned the filters. (they needed doing. running for almost 6 years) currently have disconnected second monitor connected by D-Sub and CPU temp has dropped by 12C (72C - 60C) if needed i will post the AIDA summary. Motherboard: ASUS Commando CPU: Intel Q6600 Ram: 4x 2GB sticks (2x Micron, 2x Generic) OS: Windows 7 Ultimate (genuine) At time of posting CPU temp  is 69C

Question by furby   |  last reply