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Way Of Detecting Humans?

Is there ~~an easy way~~ a best way of detecting humans in the dark, or in a forest? Me and my friends play airsoft, usually in a forest, and it's hard to know where the enemy (other friends) are. I'm a sniper and I want an easy way to detect them. One way would be a thermo-camera, but those are expensive. Is there a better way?

Topic by guyfrom7up    |  last reply


Heat sensor?

I need a heat sensing circuit that detects, if my server blows out warm air to switch on forced ventilation. This module should work as a stand-alone module without any connection to the server.

Question by Bernhard 52    |  last reply


7805 and 555 timer circuit heat.

Hi all! I made a test led blink circuit with a 555 timer on a bread board. Just a basic two led blink circuit you can find all over the place. I used a 7805 for a supply regulator with power from a 9v batt. The circuit functioned fine (to my knowledge), but the 7805 got REALLY hot. I've used 7805 in opamp circuits with a 7.2v batt and no detectable heat. Is what I'm experiencing normal? Or do you believe something I did was wrong. If I remember correctly (I'm really tired as I write this) i was using 100nf caps on both ends. Thank you Nic

Topic by Mrlzeppelin    |  last reply


Would a survival blanket help a criminal to evade detection from a thermal camera?

 I have a survival blanket that claims to reflect back 90% of my radiant body heat and I've always wondered: If a criminal were to hide under a bush wrapped in a survival blanket would he be able to evade a police helicopter searching with a thermal imaging camera? Thank you.

Question by FriendOfHumanity    |  last reply


how should i charge my 4xAA NiMh battery pack?

A project that i am building is going to be powered by 4 NiMh batteries in series, i need to be able to just plug a cable(wall wart) into my project box to charge the battery pack. there will be an arduino clone(with plenty of free pins to spare) available which i could use to control a charging circuit with it. how many volts and amps should i charge the pack with? how do i detect the voltage drop when the batteries are done charging? is heat detection necessary? the batteries are 2000mAh each btw.

Question by solidacid    |  last reply


Can I use a regular digital thermometer as a cylinder heat temp gauge?

Hey guys, I want to make a cheap cylinder head temperature gauge for my 150cc scooter. I have owned one before which worked well but it was rather expensive. I'm more interested in being able to detect a temperature spike and avoid a blown motor than determining an acurate temperature. The last gauge I owned used a probe with a ring on the end that acted as a washer between the spark plug and the head. If I buy one of these probes:  http://www.ebay.com/itm/Thermocouple-CHT-Sensor-Probe-Cylinder-Head-Temperature-14mm-/120861470119?pt=LH_DefaultDomain_2 And a digital thermometer with a probe like this: http://www.ebay.com/itm/Digital-Blue-LCD-Temperature-Meter-50-150-Probe-/230650228821?pt=LH_DefaultDomain_0&hash;=item35b3d33055 Could I just splice the wires together and be away laughing? I'd need to find out what the temp range of my engine is first.....my last 2-stroke 150cc ran at about 275F and melted at 400F, 4-strokes should run cooler right? Any thoughts would be appreciated :)

Question by tig5    |  last reply


Control bulb with inductive proximity sensor

Please see attached diagrams in my other message below. I am using an NPN NC inductive proximity sensor (specs attached) to control a light bulb. The bulb is normally on and goes off when metal is detected. It is a 12v/21w bulb, powered by 12VDC. I have placed a heat sinked TIP120 NPN High Power Darlington Transistor 60V 5A TO-220 , a 2.2K 0.25W resistor and a 560R 0.25W resistor as shown in the circuit diagram on the right. Please ignore the left diagram for the LED. voltage readings for sensor with no metal detected: Between brown and black: 12.06/07V & -12.03/04V. Between blue and black: 0.0033V & -0.0032V (3.3mV & -3.2mV)  with metal detected: brown/black: -0.6/7mV & 0.7mV  Blue/Black: 11.96/97V & -11.93V Although the sensor is powered and detects metal ok, the bulb stays on. The polarity of tIP120 is correct and gives out heat ok. I can't figure out what I'm doing wrong so could you please see an obvious error?? thank you

Topic by nathanimate    |  last reply


How to interconnect a fire/smoke detector/alarm with other fire alarms and further connect it with arduino

Hello StrangerI'm trying to make a certain combination of fire alarms and fire sensors.the situation we have is...there's a couple of interconnected fire alarms, connected through wires , just like a normal fire detection system.i want to make a slight addition to it. Can i interconnect another heat/smoke sensor with them, which can trigger the other alarms. the other alarms when triggered should also trigger the ADDITIONAL sensor I HAVE ADDED. Also i want an ARDUINO connected to the additional sensor i have attached, which can detect the sensors when it goes off, and i can use it accordingly for other functions. this will have a couple applications.bottomline, i need a chain to be formed by all the fire alarms and my sensors, and as soon as the alarms goes off, the sensor detects fire/smoke, the ARDUINO should receive input from the sensor, and the arduino will then be further used for other functionssorry for being vaguealso if this goes under 'sensors' then please help me out with the same.thanks for readingRegardsDaInnovator

Question by DaInnovator    |  last reply


Interesting and alternative uses for electronics components? Answered

At my school, old wise men teach us all kinds of circuits and concepts, many using components in ways they were never intended for. Thermal cutoff for a power supply uses normal 4007 diodes as temperature sensors. Hollow pieces of stripped wiring plastic, heated slightly and used as heat shrink. Reverse voltage of an LED used to detect daylight and guide a solar tracking motor. 21W light bulbs used as constant current sources because of their PTC characteristics. Fuses made from single strands of copper, doubled up to handle greater current. There must be more. Using components and junk in ways they weren't intended opens up all kinds of possibilities for electronics people and students on tight budgets who don't have access to components and technology. Are there other smart ways to put the characteristics of certain parts to smart use?

Question by Udon    |  last reply


Scholarship Robot Proposal: Perimeter Security Bot

A few years ago my house was broken into. Thankfully, nothing of to great of value was stolen. They only stole $60 out of a small personal safe (not traceable and did more property damage than anything else), had no idea who broke into our house or if they were ever caught, and no way of providing any evidence to convict anyone. So it got me thinking, what if I had a bot that ran around scanning the house (visually and audibly), linked up to an old pc that uploaded live feed from it, and have an alarm capability that if it detected someone that would trigger the iRobot to have the live feed stored to the hard disk on a remote web server. That way if we do get broken into ever again, I will have evidence on file! The iRobot would have a "normal live feed only" function and an "alarm on" function. The difference between the two would be that the normal mode would just send live feed onto my web portal and not store it on the remote hard disk. That way if someone is home it will not store hours of my family walking around, while my hosting storage gets filled up. "Alarm on" mode would allow the iRobot sensors to sense a person and tell it to store the feed on the remote HD. It will do this for 10minutes, after the time is up it will then reset the timer, and begin the whole process again. Again, this is keeping any false alarms (such as my cats) from filling up HD space. Sensors: To detect any object (like a human) only requires an IR sensor to detect a moving body of heat. It is like the ones you see in some buildings with the plastic covers over them and leds blink when an object passes in front of it. Another words a thermal motion detector I would also incorporate a high frequency detector. It would detect loud sharp noises, like glass breaking. Then of course the crt camera with audio linked to an onboard wireless transceiver. old PC with Proprietary software and high speed wireless router I eventually will hope to one day build this robot, if you have any suggestions I would be glad to hear them. Thank you for your consideration!

Topic by Kira_Koenig    |  last reply


Overheating Car - Causes and Short - Term Solutions

Overheating of the engine not only occurs in the summer, but can also occur in daily driving. In particularly, high-speed running cars, engines, and air-conditioning systems can cause boiling phenomenon when the water temperature is too high. It's dangerous to overheat the engine. It may hard luck that what can damage the engine. When driving on highways at a higher speed, or when climbing a car, if the pointer of the water temperature gauge enters the red zone and stays high, appropriate measures should be taken at this time. Here's how to handle the engine overheating.There are many causes of overheating, including insufficient coolant, cooling fan cooling the coolant has failed, thermostat failure, and coolant temperature sensor failure. If you deal with it improperly, it can lead to an expensive engine failure. Therefore, timely detection and proper disposal of overheating can effectively reduce losses.First, poor engine cooling: Poor engine cooling can cause the water temperature in the tank to be too high. When longer the water tank is used, the more internal scale will build up, resulting in poor heat dissipation in the radiator. The water with too high temperature will not release heat, and it will evolve into a "pan". In addition, the ventilation hole of the radiator is also a common cause of poor heat dissipation. If the external blockage is not ventilated, use a water gun to clean it up. If the inside of the radiator is blocked, then clean it with a cleaning solution. Second, the cooling system is not working properly, resulting in poor heat dissipation. At this time, check the tightness of the fan belt and whether the fan blades are deformed or broken.Third, the thermostat automatically adjusts the amount of water entering in to the radiator according to the temperature of the cooling water, so as to ensure that the engine works within a suitable temperature range, which can play a role in saving energy consumption. If the engine is overheated, check that the thermostat is working properly. Starts at 70°C and fully open at 83°C. When the height of the fully opened valve is not less than 9 mm, the thermostat can be put into the water for heating inspection. If the thermostat can't be opened or the opening degree is not enough, the thermostat needs to be replaced.

Topic by violantez    |  last reply


IR sensor of some kind? How does it work? Answered

I got these from a computer mouse, used for scrollingwheel movement detection, different components were facing aech other on opposite sides of a pierced wheel. (The mouse had two scrollingwheels - so there are two pairs on the picture. Manufacturer A4tech.)The ones in bottom right corner are probably IR LEDs -  no visible light when current flows through. But the black things are a puzzle - light sensitive transistor is supposed to have two legs not three. Two transistors or diodes in one package? And I get no reading with multimeter - no resistance nor diode polarity between any combination of the legs. Tested both of them. (They have to be really heat sensitive for both to be broken after my desoldering.) And there is no component number on any of them. Does anyone know, what exactly are the three leged components? And can they be still in working order despite the no reading on multimeter?

Question by Libahunt    |  last reply


Challenge: design a water cannon for deterring cats

The Cats page (https://www.instructables.com/id/Cats/) incorrectly states that 'Everybody loves cats'.  In fact, everybody does NOT love cats, particularly those whose resent their tendency to massacre the wildlife in our gardens. I'd like to improve the odds of survival for all the birds, amphibians and small mammals in my garden, but without causing physical harm to the cats.  I've tried scent-based cat repellents without success, and I completely reject the idea of indiscriminate noise scarers. I can't police the garden 24/7, so my preferred solution is a water cannon capable of detecting a cat and soaking it. To keep things simple, I'd be thinking of using mains pressure to power the water jet, and batteries to power a motion sensor (infra-red). To be useful, the design would need to: - hit targets within a user-specified arc and at varying distances - allow the user to configure the sensitivity of the sensor, so that cat-sized heat sources are treated as targets, but smaller mammals are non-targets - avoid being triggered by foliage disturbed by the wind. For extra credit, the design could: - use solar power instead of batteries - focus the jet at the target, rather than spraying mist over a large area

Topic by pspinks    |  last reply


A Thermal reacting LED? Answered

Ok so I don't know much about LED's, or let alone anything about how electronics work, then only thing I know is how to code on a computer, for a computer, I don't even know how to code a PIC card or whatever... But anyway, I want to make an LED react based on a thermal image, so its camera or Thermal LED or something detects heat in a room and adjusts the power of light on an LED and also turns it off and on, kindof like another tutorial that someone had with the light table, except they didn't have instructions to build it. If you want I can draw a picture of what it should look like, but basically I want to end up with a bunch of LED's to light up when i enter my room, and later on I want to make it so that they shut off when I clap 2 times and make them udjust different light areas, so when I walk in different areas of my room, different lights go on, and then later after that I'll make it so I can change the colours of the lights by saying a different colour. If someone can help menu would greatly appreciate it and when i build it I will post the instructions on this site :D Thankyou

Question by jayjay110    |  last reply


My iRobot Create Idea...

My iRobot Create Challenge idea is this: Have you ever woken up in the middle of the night and needed to use the restroom or get a glass of water? You don't want to turn on the lights because you don't want to deal with the brightness and waiting for your eyes to adjust. At the same time, you can't see where you're going, and you don't want to run into things, or worse, stub your toes on some harsh corner. The solution? Have a little guide robot. Built on the iCreate platform, the "NightGuide" (as I call it) will be able to record a path from your bedside to the kitchen, the bathroom, or anywhere you might like. When you wake up, you simply press a button on the robot to select a destination. the robot turns on low-level lights towards the ground and guides you quickly to your destination. Once it's reached the destination, it stops and awaits orders. When you're ready to go back to bed, you press a button and it leads you safely back to bed. What happens if it runs into something? Should the robot run into something while it's leading you, it stops, and increases the light it's providing to give you a view of what's in the way. Move it out of the way, and a sensor tells the robot it's a clear path ahead, you continue to your destination unimpeded. The distance and direction are handled by the Create's internal systems. Additionally, starting and stopping points can be defined by a device similar to the virtual walls utilized with iRobot's Roomba vacuum. IDEA #2 I just came up with this one, So I thought I would append it. My second Idea is to use the iRobot Create to make an item finder. Utilizing RFID information, you could place a tag on anything that you might use. Your Keys, your phone, the TV remotes, whatever. When you realize something is missing, you turn the Robot on and off it goes, when it comes near, it beeps to get your attention and give you a better idea of where to look for what it is you're looking for. IDEA #3 These just pop in my Head, so I hope it's okay to continue attaching. I was thinking about my 5 year old niece and ways to keep her occupied. For a 5 year old, what could be more fun than a robot that plays hide and seek with you? Either through use of an IR sensor, or a pyro-electric sensor, the robot would be able to find a person through heat detection. Or in another option, an RFID tag would be put on the person and the Robot could find using that. In order for the robot to Hide, it could use proximity sensors (Sonar or IR) and a photovoltic sensor to find a small dark space where it could hide, and off your 5 year old niece goes off to find it. If that's too difficult, a Marko Polo system could be introduced In which you could call out to the Robot, which it would respond with an audible tone. If that's too difficult, a wireless button press could make the robot respond with a tone. Upon finding the robot, you press a button to reset it, and play again!

Topic by aarone    |  last reply


Input problem with OpAmp-controlled ZVS Induction Heater

Hello, Idea: I'm trying to build a circuit which uses an OpAmp to drive 2 mosfets, which power the LC tank of an induction heater. The idea is to detect when the voltage over the LC tank crosses zero, and at that voltage I would make the 2 outputs of the OpAmp change states from fully on, to fully off. The two OpAmps (both inside one chip) have their positive and negative inputs connected to eachother, but with reversed polarity. This would make sure that one output is high, and the other one is low. Why use an OpAmp? I wanted the MOSFET gate switching to go faster as usually, because in the mazzilli circuit, the gate voltage actually slews at the same rate as the LC tank's voltage slews when it crosses zero volts. In the mazzilli circuit, it actually doesn't switch when the voltage is 0v, but when the tank voltage drops below the gate threshold voltage. This would mean that you are always switching current at 5v (for example) instead of at 0V. So for these two reasons, I wanted to try switching them with an OpAmp. Measurements: Probe I on drain 1, probe II on drain 2, and GND on the circuit's ground, gives me an expected result: when switching states, at 0 voltage of the LC tank, the voltage on one side stays low (since it's pulled to ground) and the voltage on the other side goes from 0v up to 50v, back down to 0v, like a sine-wave. Then the OpAmps switch again, and the one side now goes up to 50v as a sine wave, and the other one stays low at 0v. All good, this is working just fine. Probe I on the one differential input line, probe II on the other differential input line. Since this is nothing more than just a 1/10 voltage division of the previous measurement, I'm also expecting the signal to be exactly the same, but 11x smaller. -> problem: However, this does not happen. Because of some strange reason, as you can see in the scope images: Both channels go high, Twice per cycle, instead of going high only once per cycle, and staying low for the next half of the cycle. This really isn't good! Do the inputs affect the waveform in some way? Remarks about scope images: Image: 2 gates Blue gate voltage seems 'quite' fine. Turning on looks good, turning off is not really good becuse if tends to turn on for a short time once again, before it fully turns off. Yellow gate voltage is terrible. Turning on doesn't happen as expected. Voltage drops back to 0 for a long while which is very bad for the circuit. Frequency seems fine; 50kHz is as expected with the 14µH and 6µF. Image: 2 drain voltages These voltages were measured with a 1-10 voltage divider, and thus show only 1/11th of the actual voltage. This is getting close to what I want the LC tank to do. The voltages seem quite like sine waves. I suspect that if the gate voltages would be as they should be, these drain voltages would also be perfect sine waves. The regular sine amplitude of 50V is as expected, with a 24V supply voltage, but at the moments when the drain voltages strangely drop down to 0v, as you can see in image: '2 gates', at these moments the drain voltage seems to spike over 250V!! Image: 2 differential input lines This is the image which I don't understand. I expect the same wave as in the previous picture, but only 11 times smaller because of the voltage divider. However, the voltage does NOT reach 0v while the drain voltage does, and its shape is also completely different. In this image, both channels are doing one (half) sine wave, twice per switching period. They should be LOW for half a period, as the drain voltages do in the previous image. Better quality images: 2 gates 2 drain voltages 2 differential input lines schematic Datasheets: OpAmp: http://cds.linear.com/docs/en/datasheet/1497f.pdf MOSFETS: http://www.vishay.com/docs/91262/91262.pdf Coils and capacitors: Line inductor value: I'm not sure if this value is correct. Center-tapped main coil inductance: This value should be pretty correct, I calculated it by measuring it's size and windings, and the operating frequency is also nearly the same as the calculated one. tank capacitance: 6 times a 1µf MKP capacitor Questions: - Why these strange large spikes? - Why is the waveform suddenly different when reading it near the differential inputs? For the first time ever, I can provide you with scope images! I finally bought a (quite cheap) oscilloscope. I hope it helps a lot. Oh, and one more thing: The induction heater does actually work already. I'm getting huge currents in the LC tank, since the 6mm copper tubing gets hot after a minute. Water cooling has been added, and it works like a charm! The MOSFETS do get quite hot after 15 seconds of heating an object, or after 40 seconds of heating nothing. This, probably because the gate voltage isn't what it should be. Kind regards, Electorials

Question by DELETED_Electorials    |  last reply


QI wireless charging - what you need to know but won't find on the pack

These days using a charging cable for your phone or tablet is like connecting it to the printer or laptop with wires.You only do it if you really have to it seems.Your coffee bar or snack restaurant has the wireless chargin pad in the tables for your convinience.Your car has a holder with charging pad and at home you might have three or more of them...They are convinient and unlike a cable won't wear out your USB port over time.But do you pay a hefty price tag and always go genuine or do prefer to save a buck or two by going the aftermarket route?What's the difference between genuine and aftermarket?Apart from the price it is often the overall quality.The charger for your phone works with the charging pad if it did not come with a dedicated wall adapter anyway.And because it is a brand name product chances are slim you will be bother by big problems or even failures.As with all things the devil is in detail here.This devil is caled "QI" - or better what dollows after the QI on the sticker of your charging pad or cheap receiver coil that you add to your phone.QI READY!QI COMPATIBLE!WORKS WITH ALL QI ENABLED DEVICES!There is more slogans you find in the listings, on the pack or the product itself.They all inform you that you can use your phone, tablet, watch or ear buds with the wireless charging solution they try to sell you.They also inform you this way that it is not really a good idea to buy the product or if you already have that you should not use it ;)Only if there is the official QI logo on it and right next or under it it reads "QI CERTIFIED" you can be sure the charging pad is actually up to specs and won't damage your device while charging.Don't be fooled by the cheap knock offs or the expensive ones for that matter!Without QI certification you simply never know what the thing might do to your expensive phone...It is things like foreign object detection, monitoring the charging conditions, temperature and of course the efficiency that differenciate a certified charging pad from the rest out there.I have taken quite a few of these pad apart - couriosity killed the cat...Even products that inndicate on the plastic housing that it was made last year often have a circuit board from 2016 or before on the inside.Not really a deal breaker if the thing can be prgrammed and most can during the manufacturing process.However: Not all can be fixed on a software level to keep the charger up to todays specs!!For me the dead give away are all these charging ad claiming to be able to provide "wireless fast charge" or whatever name other companies use to indicate it can charge your device in more than the slow mode.Unless there is a USB-C or lightning port for the cable on it the thing is a fake!There is no power delivery standard (PD) defined for micro USB.Sure, the normal USB2.x standard allows for 9V on the power lines but with several Amp limitiations.Even worse for the connectors as they are simply not desinged to handle 10, 15 or now even 30Watt of power.This is further complicated by the USB standard itself.For example a wall adapter that is capable to provide the three major charging protocols should come with a USB 3 outlet.But since the same standard applies for the blue USB ports the charger might offer you the convinience to use normal USB cables instead of USB 3 ones.Why does this matter in this case?Charging standards and why they suck ;)If you bought a wireless chargin pad capable of fast charging then chances are that you went cheap or had bad advise and got one with a micro USB connector.And now chances are high that the charger for your phone came with fast charge option but only with a USB 3 outlet.Before you make any attempts to get the two to mate properly: Check the lable of your chraging pad!!!It should clearly indicate that it uses 5V AND 9V.The 9V part usually has a lower Amp rating but that is fine with the higher voltage.The 5V part on the label should read 2A as a max!If you see only 5V but with more than 2.5A or 2500mA on the lable please don't not use the fast charge option!!You would need a high output 5V charger for these knockoffs as normal ones won't provide the require juice.Even if the pad indicates it accepts 5V AND9V for the charging, having a micro USB port makes it a big gamble.Most of these pads won't even a temp sensor on the pad or a fan on the inside and rely only on what your phone or tablet gives in feedback.This can cause severe overheating as these cheap pads simply won't have a clue how hot things might get.Ok, got it, but just o make sure....A good charger is capable of providng 5V and 9V for charging devices.A good wireless charger comes with a USB 3 port or has a dedicated wall apadter included.Both have the QI logo and state that they meet or exceed the QI certification.Without logo and certiication they are just knock offs with questionable safety and performance.Q and A:Q: My wireless charger and phone support fast charge but it does not seem to work?A: Is you wall adapter rated for fast charge at 9V and does the wireless charger meet the standards of your phone?As said, all three must match to work properly, most pads will indicate the fast charge with a different color LED.But if it does not have a fan chances are your pad won't provide a meaningful difference in fast mode.Q: My wireless charger keeps cycling between fast and normal or drops out for a few minutes and continues - why?A: Most likely your phone or tablet indicates overheating and regulates the charging down to a safe level.Cheap wireless chargers, especially the ones without a fan often fail to provide the required cooling for the phone.This can be especially tricky if silicone covers are used.Q: Why does it take several times longer to charge without a cable?In most cases the maximum current your wireless charger will provide is around 1000mA - or 5Watt.Only if wall adapter, wireless charger and phone are set and capable of fast charging the power will be higher.Most fast wireless fast charges will then provide up to 10W, some of the newer ones up to 15W.But even then there is still the problem of heat that slows things down.With a cable you might chrge your phone at 10W within 2 hours.The wireless charger on 10W with proper efficiency and all would still need at least half an hour longer for the same.Q: What about interference?This is the part no one wants you to know about ;)The QI charging works at frequencies between about 120-200kHz.Some go as high as 25kHz but does not matter really.What matters is that you literally place a RF transmitter on your desk.Now, 5 or even 15W might not sound like anything, especially if you consider the charging works only at a distance of max 4cm - and that is the theoretical max, in reality anything above 1cm is likely to end your charging experience.....It does not mean though that these RF waves just disapear aft a few centimeters...You might be surprised about the signal strength if you use a radio scanner or RF dongle on your laptop in this frequency range while charging...Every tried your wireless mouse next to the charging pad? ;)The official claim is no that due to the desing and power management there is little to no leaking of radio waves.Highly doubtful in a plastic eclosure for the electronics, which is confirmed by the above simple to do tests.If you want to do some "research" yourself then do what I did:Buy some cheap pot plants that are small and require little care - but something leafy or with flowers.Place a plant right next to your heavily used wireless charging pad, another as healthy as matured plant in a different room or at least 5 meters away from the charger.Care for both plants in the same way and observe how they deleop over the follwing weeks or months ;)If you happen to have a really old wireless charging pad or a really dirt cheap knock off then dare to try the ring test.If you can manage to get finger with a ring on it between the chargin pad and phone (while the phone actually still charges) a good charger will turn off, a bad one will start to heat your ing up - do at your own risk!With that in mind: Would I recommend the usual nedside table charging solution?Honestly, I would have to say no here.Radio therapy might be good for something but should not come for free from your phone charger.The levels might be low but there are no meaningful and verfied long term studies about the effects of long term exposure to UHF radio waves.But anyone dealing with CB radios will tell you to stay away from a radiating antenna....Then again, if you make hundreds of phone calls and are a heavy WiFi user the little bit of added radiation from your charger won't make much of a difference ;)

Topic by Downunder35m  


PSU design (major revisions): Transformer calculations help?

Recently I have attempting to design a proper dual-rail power supply that will allow me to set a voltage as low as +-1V up to +-30V in 0.1V increments at (hopefully) 3 significant digits (at least for the lower voltage settings). Anyway, this supply is also going to be current limited to up to 5A,again, it can be set to just about anything. I plan on using an Arduino micro-controller to set the output. In order to do this, I plan on using the analogWrite functions, or better yet, a legit DAC. There will be 4 outputs from the Arduino that will set the power supply output by applying a 0-5V voltage on the input of the 2 current limits and 2 voltage sets. (one for the negative rail, one for the positive). However, I have kept running into the same problem: how do I plan on driving this linear power supply with up to 200W*? My first idea was to use a a MOT, due to their high-power capabilities, and re wind the secondary with the right number of turns to achieve this output. However, I have heard that these transformers are not optimal for continuous running due to their poor and cheap design. (losses are very high). My second idea was to search around for a 250VA transformer. However, even until now, the VA rating confuses me. How does VA compare to W? I know this has something to due with reactive power, real power, and apparent power. However, I have no intuition of any of these 'powers.' How would I go about calculating the correct size transformer for the job, also, I am going to assume this linear power supply has the properties of a resistive load, since it is rectified and smoothed with a filter capacitor, so practically nothing should react with the AC power. (unless there is something more to the full-bridge rectifier setup I am considering.) This is when I came across unwound toroidal cores found on eBay for $25, the perfect price range! However, this has raised more questions! to start off, beyond turns ratio, I do not know now many turns I need for the AC side of things. I know intuitively and from experience, mains-frequency transformers do not work with only one (or even few) winding(s). I think this has to do with saturation, but I'm no expert by any means. and the inductive reactance of the transformer's primary. How do I calculate losses, inductance, and other important parameters of a homemade transformer like this? Things get very nasty when I look back at rewinding an old transformer. Now I have all these questions about inductive reactance, power, currents, magnetic flux and saturation, but also, about determining the original power rating of something like a very old small welding transformer or one from a large 10A car-battery charger. Is it possible to approximate the power by measuring the dimensions of the core? How close will this approximation be?  After getting frustrated with this, I considered alternative approaches. What if I purchased 2 ~20V ~6A SMPS (switch mode power supplies) connected them in series, and connect the center tap of my linear supply to the joining point between the 2 SWPS's? Would this be unstable and be bad for the SMPS if a load was connected between the 'outputs' of this new center tapped supply? Would any sort of balancing be required? Also, a bigger problem includes how this will be connected to my linear PSU design. With a low voltage @ high currents, I would be wasting a LOT of power, power that has to be dissipated away from the transistors. This heat can approach 200W, which is company unreasonable! Anyway, I would them have to either a switching preregulator, or modify the SMPS's so the voltage can be controlled easily and varied between, say, 3V to 20V. absolute accuracy is not required, close enough, and rest of my PSU should handle it. This becomes seemingly impractical too, and many other considerations need to be made. What should I do? what are the calculations and factors I need to know? i do not have an LCR meter to measure inductance, so trial and error is out. Does anyone here have experience at this? Help would be greatly appreciated! *The 200W figure was calculated by taking 40V, (What I believe would be a safe to allow some slack for +-5V voltage drop across my 2 shunts and transistors) and multiplying it to 5A of current for the maximum power output. ------------------------------------------------------------------------------------------------------------------- I have added an image of my current design, and I have modularized it the best I could. The YELLOW is all my current power-management circuitry. Currently just a transformer with many taps, going to a currently-undesigned switch box that will change the voltage on the output, which is then rectified and enters a filtering capacitor, finally entering the circuit.  The GREEN field is the voltage set. It is the most major part of the PID feedback loop, along with the ORANGE field. It works simply by feeding a voltage to the positive of a op amp configured as a comparator, and with negative feedback from the output. It then outputs a signal to the transistor, turning it either more ON, or more OFF depending on how the output voltage compares to the +Vset. The negative portion is largely the same, but the input voltage needs to be inverted so the output voltage is set negative properly. I was not able to use less than 2 op amps for this portion, unfortunately. The ORANGE field is current set. It works by measuring the voltage drop across the shunt resistor, and outputting a unity voltage that is referenced to ground, instead of to the positive rail. (It took me forever to finalize and perfect that!!!) Anyway, this voltage is then fed into a op-amp configured as a comparator to drive the transistor. The BLUE field is my switching regulation topology, which is controlled by both the ORANGE and GREEN fields. Do you like my use of diodes as a super-simple voltage or current selection switch? the op amp that outputs a lower voltage is the one that gets 'listened to' by the transistors. This way, current and voltage mode enable properly. This does add a small problem when it comes to powering the op amps, all of them have to be powered off of slightly higher voltages to swing the full range due to the voltage drops of those diodes. In the PINK field is simply a single-transistor solution to a constant current load. This allows the regulator to be regulated even at very low voltage set levels. This is why I am able to achieve a +-0.5V on the output (at least within LTspice) Finally, and most unimportantly, the light PURPLE fields have a simple ultra high-gain difference amplifiers that will detect if the output current and current set are the same, and turn On or OFF the respective LEDs. The green LEDs are voltage-mode indicators, and the red LEDs are to show when current-limiting mode comes on.

Question by -max-    |  last reply


"Sonic" drilling or cutting

If we look up sonic drills today we usually get some fancy machines driving pipes in the ground, preferably softer ground.But the term includes all types of machines that use sonic vibrations to advance through a media.With the ancient and claimed to have never existed technologies in mind I did some digging...In the food industry vibrating knifes are quite common, same for "air knifes" on softer food.Even in the meat industry they find more and more uses now.Ultrasonic cutting or welding is the same thing and included in "sonic".Same for some experimental sub sonic drilling methods currently being tested.The general idea might be as old as using vibrating equippment to compact stuff, like concrete, bricks and so on.What you can compact by vibration you can also make "fluid" by vibration.Industrial feeder systems utilise this to the extreme by even making light and fine particles like flour move like water without causing any dusting.What all the techniques have in common that a suitable tool or tool head is used and that it is attempted to use the most suitable vibration frequency for the job.Anyone operating an ultrasonic welder knows the pain of finetuning for a new electrode or just new part to be welded.What does that tell us now that makes the understanding easier?Take a bottle of ketchup, preferably one that is still quite full.Turn it upside down and noothing comes out.Shake it a bit and you are either lucky or drowned in red.But hold it at an angle and start tapping it and the red sauce flows out easily.What it true for most newtonian fluids is in some way also true for non-newtonian fluids.Ever mixed corn starch and water to make these funny experiments with it?Hit it hard and it reacts really hard and is not sticky at all.Leave your hand resting on it and in sinks in and sticks to it.Stirring it very slowly is easy, go faster and you get stuck.You can do similar things with by using an external source for vibrations.For example a vibration speaker mounted to a smal cup of the goo.If you place sand on a sloped piece of plastic or sheet metal then at a low angle it will pile up easy and stay.Start vibrating the plate and the sand will start to flow off.Works fine with a vibration source mounted to a piece of steel bar or rod and a bucket of sand too.Trying to press it into the sand requires a lot of force, especially once you are a bit deeper.Let it vibrate properly and it slides rights down.If we can do the simple stuff as well as really complicated stuff in the industry then what about other materials?So far we use vibrations to make things move out of the way, compact things, transport them or to heat them up for welding plus some cutting applications.Considering the variety one might wonder why no one tries it for "difficult" materials.Machined surface can be found throughout ancient history.Finding "machined things" were vibrations was clearly used is a bit harder.The great walls are not a perfect example here as the views differ quite a bit on how they could have been created.But if we leave things melting them or a secret concret like recipe for creating for example granite then vibrations start to make some sense.You find some interesting videos on youtube where people use speakers, wires and rocks to confirm you can actually "machine" them by vibrations.Especially granite has some quite musical properties, big boulders as well as smaller ones produce destinct sounds when you hit them hard.Tests and measurements were made on granite and other hard rocks to check how fast sound travels in them , how it is refeclted and where the sound comes out or affects the surface the most.Lets just say every sample gave different results.Shape, density and dimensions affect not just the resonant frequency but also where and how the sound travels in the rock.What if??We can use a simple speaker, a plate and some rice to see how patterns form under various frequencies.Works with sand or other granules as well.The interesting patterns are the so called harmoncis.Here we see clear and destinct patters, sometimes with extremely fine lines and areas of softly vibrating granules.Some people say these harmonic frequencies have all special meanings and uses.We mainly used them to avoid problems.Imagine your new TV would not have a housing tested to be stable with all frequencies the speakers can produce.All of a sudden your back of the TV might start to rattle ;)Same for car engines.Harmonic vibrations are eliminated wherever possible.Otherwise they could multiply and affect other things in the engine or around it.Simply put it means we have various options to detect and measure vibrations on a surface or in a system.Back in the day every half decent backup generator had a mechanical indicator for the frequency of the supplied electricity.A set of tiny forks with the desired on painted red and several on either side of it.These forks were designed to get into harmonic and therfor quite intense vibrations at their set frequency.If the one for 50Hz looked blurry then all was good ;)The same principle god be applied on a big boulder of granite.Place the "vibration meter" at the desired spot and start moving around the vibration source on the surface until you find a spot that causes maximum response on the meter.Best thing here is that if you then place that surface area onto another peice of fixed in place granite both pieces will start to loose substance if vibrations are applied.The fine sediment forming is then usable as an indicator where to move the vibration source to continue once the effect literally wears off.Is it feasable?Well, if we trust mainstream science then the answer is no.A huge amount of vibration energy would be required for such a hard material, despite ancient proof that says otherwise.Semi industrial test also seemed to confirm the theory as only with very high amplitudes (loudness) and while automatically adjusting for the resonant frequency changes a measurable amount of material was removed.I struggle a bit with that as for the testing tool heads made from hardened steel or carbide were used.And that with little or no regards on how the head and tool itself affects the output.I mean in terms of having the max possible movement happening right t the tool contact surface!There is a huge difference between applying a vibration to a tool and using a system, tool and tool head DESIGNED to work at the desired frequency!Otherwise we wouldn't need a computer to design and test a horn for welding purposes or shade a knife spefically so that the vibration go along the right axis and in the right direction.You not break a hard thing with a very soft thing unless it travels fast enough to become harder as the target!This complicated explanation basically just confirms that if you hit water at a too high speed then it will just break you into pieces instead of offering a soft splashPlease do not jump of bridges or such to confirm this yourself!!If that is really true and science says it is, then how about the other way around?Works fine too, or we wouldn't have pressure washers or water cutters.Now for the part where I hope some really smart people leave helpful comments:If we can cut steel with just a stream of water, then I ask:Isn't for example copper much harder than water?Steel is much harder than copper but water cuts through it.The answer here it simple or complicated, depending on how you want to expain how it works.Comes down to speed and pressure plus the right nozzle shape to prevent a beam expansion.But then water is indeed "harder than steel".Questions:Lets say we would use a copper pipe that in lenght, thickness, hardness and diameter is optimised to transmit a frequency so the pipe end sees the max vibration like a feed horn for ultrasonic welding.Not to hard to calculate these days :)Now imagine said "main frequency" would be optimised for the pipe but also be a harmonic frequency of the rock to be worked on.The pipe end would deform quickly, abrasion does the rest and it fails before even making a decent sratch that is not copper metal on granite.No matter how hard we press nothing good enough will ever happen.BUT: If we would add more hormainc frequencies to feed our pipe we can multiply the amplitude quite easy!Just try with a sound generator from your app store, needs 2 or more channels to be usable.Pick for example 400hZ on one and 800Hz on another, then finetune around these number to hear how the tone changes ;)My theory goes like this:If all "working frequencies" would just harmonics of the resonant frequency of the granite, then they can be tuned so the effect on the pipe end is minimised.The overlaying frequencies however should result in the same effect a water cutter has: The pipe becomes ultra hard.The better the match and the more you have to get it right the harder the pipe will be.Adding now a "drilling frequency" or multiple could be used to drive these harmonics slightly out of phase.Like with the sound generator on your phone we end up with a pulsating sound, or vibration.While the pipe still vibrates at the same "hardening" mix the drilling frequency creates a peak like a jackhammer.Try it by using the heaphone output on a small speaker and placing some light and tiny things into the cone.The will violently jump around during these pulsing tones.For a drilling system the output can be mechanically maximised by utilising a pitchfork design.A head holds the vibration speakers and the tynes are tuned good enough to the frequency of the speakers.Always two would have to operate in sync though as otherwise the pitchfork movement that transfers the sound down the center bar won't work.This head could then be desgined to act as a holder for a quick change of work out pipes that are no longer long enough for tuning.I guesstimate that a well tuned design would result in a copper pipe being able to drill at least 10 to 15cm into solid granite before it wears off too much.And we are talking here about just a few mm to get the thing out of tune!But would dare to desing such a thing just to confirm a theory that no one ever really dared to test? ;)And if friction welding works as good as ultrasonic welding, then what would happen if we try this with the right frequencies and vibrations instead of wasting tons of energy?

Topic by Downunder35m  


Ancient technologies revisited - Ley Lines and Magic

Ley lines are a pure mythical thing, they do not exist, they do nothing.That is what science tells us....Myths and legends however always have a tiny bit of truth and honesty in them...No wonder then that we have detailed maps of these Ley Lines available, even your favourite search engine can find then for you.Many cities were build not just along these lines but directly onlo crossings or NODES of this invisble and non-existing grid.Quite an awful lot of them have names that got translated into more modern languages but never actually changed their original meaning.In almost all cases a reference to the stars or one particualr one or some constallation.Science and mainstream history says it is coincidence....No matter where you look in ancient texts the powerful cities were always located on the most powerful parts of the Ley Line grid.And funny enough it only took us a few hundred years to come with enough science to actually confirm that these lines actually DO EXIST.But finally admitting they are real because we can measure something is slightly different in these locations does not help to bring magic back into our world.Or did the magic actually never really leave?We hear about wonders that are impossible, like people being healed from all sorts of uncurable stuff by visiting certain places that are claimed to have healing powers.Is it really a surprise that almost all of the known places we have access to are located on a Ley Line node?The modern human can't except magic.In ancient times religion took care of magic, sometimes with brute force.Later science made sure that magic is forgotten and turned into just a myth.Now the base of magic is suddenly included in science, so the only logical conclusion must be that magic is back!But where is it?If I use a fancy looking "stick" to point at a truck and make it float through the air it would not a big deal."Oh look, what a great magician he is!" and the crowd applause pleases me...They wouldn't care how the trick worked, they just know it was some sort of trickery.And if the trick indeed would be real then some scientist would jump in to for an autopsy of my body and whatever I had with me....But if I would have done something similar 30.000 years ago I would have been declared a god....Humans always seek to find an explanation for things we fail to understand.And the more we study ancient texts with our modern eyes wide open we more similarities we find.The first archeologists to see and study Maya relics had no clue about planes, so obviously they interpreted models of them as something entirely different.This and many other misconceptions were carried on throughout time till today.Those who dare to look again and question what we "know" about ancient cultures for so long are silenced....Most end up to be labeled "Alien believer"...And we still fail to accept aliens or visitors from our own future into mainstream science...If Ley Lines exist it confirms that they must provide access to some sort of energy we no longer remember how to use.Ancient texts often speak about things we would today call a vortex.Be it as a doorway, something that does incredible things or just divides the red sea...Although totally out of magic science explored in theory how energy from a higher plane or continuum would manifest for us if they enter what we can see and experience.The conclusion is that it had to be in spiral or to be precise in all three dimensions vortex like style.It is partly based on facts we can already clearly obersver when one type of energy creates different one.Like a hurricane created by the difference in air temperatures becomes self suffient and stronger although the available energy to power it appears to be way too small....And of course our modern, linear math won't allow us to fully calculate what is really happening in a tornado...A technological gimmick to access the power of the ley lines might be just something tiny, like a resonator...We can't hear our favourite radio station if our tuner does not resonate at the same frequency...Our wireless chargin won't work at all if the sending and receiving coils are not properly matched to operate at common frequencies...The available energy would not only be basically limitless but also clean with no pollution, no waste products....So why we did we forget how to use ley lines?It was religion...They exist, they have powers and energies we have yet to understand.But do we at least have any theories were their power comes from?It can't be the stars as the ley lines are fixed structures, they do not move with the starts their nodes often represent.It can't be the ground or natural formations around either as there is nothing we can detect to be different.But we could try to accept a totally different theory about the center of our earth.Science tells us we a hard crust, then some molten rock and finally a liquid metal core that is somehow spinning and creating our magnetic field....Great story but sadly based on just linear math and our current theories of things we can't actually reach to explore.Funyy then how the greed of humatiy comes to the rescue...Diamonds are expnsive, especially those rare, pure and special ones.Several mines getting diamonds from very deep down in our mantle found strange things in some diamonds.Water....Ok, not water as we know it but the same building blocks.It was only confirmed to be water because when these "impurites" were analysed science already created this type of water.Part of a great science project theroy turned reality.With enough heat and pressure water changes the state of matter, it becomes ice.To be precise ICE7.It is a bit like a very energy plasma constantly being recycled.And it has magnetic properties in its crystalline structure but also on a sub atomic level in its plasma form.How would such a reaction be possible?Gravity of course.If you have water without gravity afeecting it you get a perfect sphere.With enough water your "drop" creates its own gravit by its mass.Add more and more more water and gravity will compress what is at the center.Keep adding and you create a minature sun running a cold fusion process with just hydrogen and oxygen.The natural forces of your movement around the sun and what is manipulated by the moons gavitational impact keeps the up the required motion for the fusion process.Ice7 could not exist in molten lava core with a spinning metal ball at the center.But molten lava under our tectonic plates and their movement is not problem at all if their mass is nothing but "floating debris" covering a huge cold fusion reactor.Compression by gravity and a "water" core create enough friction to melt rocks.We use the same priciple in friction welding in our industry...Unce the firction is great enough the to be welded metals melt and theep meltig until the rotation suddenly stops and all goes solid again as one single piece.The ley lines might be nothing more then emissions from our cold fusion reactor, like directed radio waves if you like to make it too simple.But ley lines are on the ground so the entire therory of Ice7 and cold fusion is just crap!?Science does not give up that easy and confirmed they are actually extending all the way into space.Satellites were able to measure the tiny variations when crossing ley lines and especially nodes where multiple lines intersect.The race to find what might be required to access the "magical" powers of our ley lines started ages ago.The only thing that has changed is the approach and who organises this search.One conclusion that was made again and again is that we will only be able to understand ancient technology once we understand what role the ley lines really play in what myths calls magic.To get a grasp how simple yet complex this understanding is we can go to the great pyramid in Aegypt.Build on a stron Leyline node and confirmed to be oriented by certain stars.You can look all the details about this up on your favourite search engine.Quite intersting once you realise the great precision and drive to aligne everything so perfectly.Even more when you realise the pyramid is also orientated properly on the ley lines.There are only a very few places on our planet that allow for the alignemnt of both stars and ley lines - they all have pyramids there with remarkably similar features or constructions to creat calendars and time keeping based on the movement of the sun and various planets.Some of these old cultrues even tracked the axial shift of our planet to have a warning system for a reversal of our magnetic field...But the great pyramid of Giza has nothing to actually track stars...Then why are all the "tunnels" to the "burial chambers" pointing prescisely at certain starts, including one in the Orion belt that even a decent telescope struggles to make visible?The same stars mentioned again and again throughout all ancient cultures....Some say the pyramids have powers, others say they were gigantic power plants, some they they were devices to accurately track the stars and to make sure whoever has the final resting place there will be able to reach and see his home planet.What if all of this has a true backgorund we yet fail to understand and explore?A now quite famous couple observing vulcanic activity around the globe managed to get quite precise prediction on not just when and where a vulcano is at risk to blow but also how severe the eruption might be.How is such an impossible "magical" prediction possible you ask?No magic, just pure science.The gravitational pull on our planet is not just affected by the moon, it just our biggest influencer in the game.Every planet out there in our soloar system creates gravity.And they all move around "randomly".If the aligned however things change dramatically.In the worst case all our planets between earth and sun are in one perfect line whle the rest of them is in a prefect line on the opposite side of the sun - the gravitational pull on planet earth is at max.Of course it is at the lowest when the inner planets are behind the sun and the outer planets behind earth.Thes seintists track this movement to predict in conjunction with the position of earth if a vulcanic active region would be subject to increased gravitational pull.Theory is it would cause and increase in magma pressure and movement.And the theory shows to be correct time and time again.Now try to imagine this:All the stars that have perfectly aligned channels in the great pyramid align with these tunnels AND all our solar planets align just right as well.If science is correct then around the time the pyramids were build this alignment was true.Get your calculator to check when the same conditions happen again and you might get a big surprise when realising the day is not that far away...Only too bad that we neither have the outer lining of the pyramid nor what was really inside these chambers at the time they were finished.Keep in mind that in most cases the pharao died long AFTER the pyramid for him was finished.We could wonder the same about many old cities in the UK, Europe and especiall Italy.No one denies that Rome was build in just seven days ;) or that it is build on a very secific point on the ley lines.Only few though know that the perfect spot on the lay lines is occocied by the center of the Vatican.Don't know about you....But if the pyramids are said to have had great powers when the time was right then what powers might the Vatican reveal when its alignment to its stars are perfect?Go ahead, start from england and follow the ley line all the way to rome.Take the names of some of the vital cities along the line and make the reference to the star or constellation they were named after.Like for the pyramid, these "bread crumbs" will tell you when the time for Rome is perfect.See what great historical events happen during past alignments and wonder what might happen during the next ;)And suddenly we get the feeling that magic is nothing but a boost of knowledge and technology handed to select few people.Only the most prestigious and "decorated" members of the church are allowed to access the secrect libraries of the Vatican.Even fewer are allowed to actually study them....And all of these few are "fluent" in many ancient languages.....So if GOD would ever return it would be in Rome and there would be people able to at least understand his written language and speak a few works in the old tongue.Imagine though another "god" would visit earlier in a religious location that aligns earlier?The race to be the first is already on whether we like to admit it or not.Only question is which god will be first and what magic will he bring us this time?Ley lines are as real as the cities and monuments build exactly and precisely on them.Some of them are older than humanity as know in from our books.Do some exploration of the ley lines nodes close to you.Listen to the myths and legends of the area, visits the places you hear about and try to see them with open eyes and a free mind.Dive into the past to find out where the origins of the stories and myths you found might lead you.Nature is all around and includes ley lines, we only have to allow to see and understand to imagine what might have been and what might be again.Magic is nothing but energy and technology observed by someone who does not know these things.Let a cave man watch Seinfeld and see what he draws on his cave wall once you and the TV are gone ;)

Topic by Downunder35m