Search for micro switch in Topics


I am trying to use a transistor to switch a 12v relay ? Answered

I am using a micro controller to switch a transistor which will then switch on a relay. I have heard that you need a resistor in between the output pin and the base of the transistor. Why is this and how do you calculate what size. Also the micro controller is running off a 12 battery which is regulated down to 5 volts for the controller. Can a transistor use a 5 volt source to active the base and then have 12 volts running through it activating the coil on the relay. I apologise for my poor electronics knowledge.

Question by legend4930    |  last reply


How to wire 2 micro switches to automatically turn off a reversible dc motor that is attached to a DPDT switch?

I have been trying to find a tutorial, but have not been able. Basically the dc motor goes forward, hits the micro switch and turns off.  Flip the DPDT switch, the motor turns on and goes in reverse, hits another micro switch and turns off again.  Where do I attach the micro switches in the circuit? I'm not too gifted in this, if you could be as detailed as possible it would be much appreciated!

Question by doyle928    |  last reply


how can i make something that flashed 12 times then lights up...?

 hello, basically I am making a party game and what I want it to do is flash and beep 12 times (like 2 times a second) and then a different light (not the same one that flashes) turn and stay on. I know it seems like a lot to ask but I cant find anything like it any ware. Thanks

Question by god ownz    |  last reply


How to use IRFZ44 as switch with pic micro? Answered

I want to drive stepper motor with pic 16f84. Can i switch on irfz44 with 5v signal from pic micro? Thanks.

Question by saikhamhein    |  last reply


LED powering and switches

I am trying to build a small display box that has 2 LEDs (either 3mm or 5mm). One LED lights the displayed item from above, the other from below.  I plan to use only 1 LED at a time, so I presume I need an SPDT-Center off micro rocker switch.  I have a small model and it provides ample light with 2 CR2032 batteries, however, I'd like to be able to use an AC/DC adapter in place of the batteries. I need help figuring out what parts I need so I don't create anything dangerous. I am confused by the terminology used for the switch...how many amps/volts would I need? Am I correct that I would need a 6v adapter? Can the adapter be wired directly to a battery holder, or can it be SAFELY wired directly to the switch/LEDs? I want to order some stuff, but I don't know what I need! If anyone can provide this info, I would be grateful! Thank you.

Topic by craigo  


What's the name of this type of switch? Answered

What's the name of the type of switch then works by rotating it, and you can keep rotating it on one direction.  Like the kind of switch that controls the volume in a car.  I'm assuming that every click switches between being it conducting and not conducting?  I need to use one with a micro controller (I don't want to use a potentiometer because they can only rotate so much) and I need to know the name so i can buy one.

Question by guyfrom7up    |  last reply


Switching voltage inputs with a chip

I have a small project I'm working on that uses rechargeable batteries.  However I want the device to stop drawing from the batteries whenever an external power source is plugged in.  (The external power source would then power the internal battery charger and the main device.)  Is there a chip or circuit that could be used for this?  My only alternative is to modify the power supply port to include a micro spdt that will switch when plugged in.  But I'd rather like to avoid that.

Topic by stalledaction    |  last reply


How do I safely connect a micro switch to a 6 outlet power supply? Answered

I have the Big Dome Push Button (sparkfun electronics) so I can start the power for an arcade machine with a press of a colorful lighted button. However, I'm new to the hobby of electronics so even this simple build is confusing to me. I basically need to connect the micro switch and LED  to a typical 6 outlet power supply. Help!

Question by Peteredbeard    |  last reply


How does one wire a motor so that it reverses automatically?

I'm looking for a relatively simple, mechanical way (by that I mean not using a micro-controller) to wire a motor so that it will reverse direction without being switched manually. The interval is unimportant, and the purpose is to have two spools connected by a loop of string (think reel-to-reel), one of which is controlled by the motor. A low-tech solution would be awesome.

Question by brandegor    |  last reply


How will I be able to switch power from sprinkler valve to sprinkler valve in air cannons?

I want to build an air cannon that uses four sprinkler valves. I want to be able to hit a momentary switch and the first valve will open. Then when I hit the momentary switch again it will open the other valve instead of the first valve. How will I be able to do this without the use of micro controllers?

Question by Pizzapie500    |  last reply


Vacuum Pump Limit Switch System

Hey Everyone... I'm Alive! I've just been really busy with my senior design project :DSo today I acquired ToolUsingAnimal's vacuum pump on loan. I'm going to be doing some vacuum bagging.... To prevent his pump from blowing out, I need to make a limit switch so the pump shuts down when it reaches full vacuum and then turns back on if some of the vacuum bleeds of somewhere.So the method I cooked up today was to use a syringe with a weight. The weight will pull the syringe open and close a micro switch that turns the compressor on. If there's vacuum, the plunger will be fully retracted and the switch will be open (off position). This method will cost me all of $5 or so (10 cents for the syringe and $4 for the switch).I was just doing some math on how much weight I'll need for different syringe sizes - and it's totally plausible (we're talking less than a pound to 3 pounds depending on syringe diameter).Question - any other suggestions or blatantly obvious/easy/cheap solutions? I know this sounds Rube Golbergian, but it's not nearly as complicated as it sounds (or looks) :D Emphasis on cheap, I just put in an order for roughly $2000 of materials and supplies!

Topic by trebuchet03    |  last reply


can i use a micro controller to switch audio or will i need to also use relays? Answered

Hi, I'm thinking about making an audio linked house (each room can listen to music playing from another) (for details read my other post) basically all the rooms are going to be linked to a central switcher witch will have a micro prossesor in it, maybe an arduino or pic. my current design uses a whole load of relays connected to the digital pins via a transistor. i was wondering if there was an easier/simpler way to do this, maybe direct onto the micro prossesor?

Question by ljarrald    |  last reply


How to bypass bluetooth device battery and connect directly to car power?

Hey all, Im looking to buy this bluetooth receiver, but it requires me to turn it on before i can use it. It has a battery and a switch. charges by micro usb. I have no knowledge of how a circuit works, but my goal is to remove the battery and switch, cut off the micro usb, solder the +/- and ground to where the switch/battery used to be The purpose is to have the device turn on whenever the car turns on.  Is that how this would work?  Thanks in advanced. 

Topic by D4VIDLE    |  last reply


How do I use a 3.3v micro with 5v signals & transistors?

I need some help with a gap in my electronics knowledge. How do I use a 5v signal as input to a 3.3v micro controller, and inversely how do I switch a transistor with 5v load, from the same micro's output pin? (@3.3v)? Can I just use a suitable resistor on the input pin, and for the output can I simply drive the 5v transistor with 3.3v at the base?

Question by NathanWilliams    |  last reply


dc motor with limit switches wireing help

I have a 1998 Trans am that has power windows. The problem is the doors are fiber glass and the motors create a lot of force on the doors creating problems. What I want to do is put a limit switch at the top and bottom of the window travel.        I'm using the factory switch that sends +12 volts in the up or down direction   I have a dc motor, limit switches and dpdt relays. I need to know how to wire it all together. If you could draw a picture that shows all wires from switch to relays to micro switches to motor that would be best. Thank you for your help     E mail dmarker5@hotmail.com

Topic by 123COOPER    |  last reply


How do I put a simple micro motor electrical circuit together? How do I achieve my goal of making this micro motor work?

I have a micro motor where the specs are DC 12V. At where I reside, the voltage output is 220V AC. I am looking to imitate a simple circuit which currently contains the following: A motor (DC 12V) A switch (volume like control switch) A component (i dont know what its called) where you can insert a small round plug from an adapter where the output specs are: 5.5V DC and 600mA 3.5W However, this circuit breaks down alot, meaning the switch will burn out etc. How do I make this to last long and make sure its safe.  Should I include a resistor? capacitor? fuse? Your answer will be very much appreciated. Thank you and have a nice day

Question by Angad08    |  last reply


How do I wire a 12V DC motor to micro switches, relay digital timer and battery?

I am wanting to wire up a door to my hen house that will open in the AM and close in the PM. I have a 12V DC powered cordless drill motor and a digital timer. Can you help me on what I need to make this all work as far as switches, relay, etc. and possibly give me some guidance on how to wire it up? Just so you know, I have very limited electrical experience. Thank you. Rod

Question by dobecool    |  last reply



Can running voltage pass through a closed relay? Answered

I am making a device which turns the light in my room on and off. The way I am doing it uses a wireless remote which came with the light, which I control by bypassing the switch with a relay for a quarter second. Any longer than a second and the light starts to dim. I also have an arcade button on a wire spread across my room that, when pressed, bypasses the switch. I know the problem isn't there. The switch has about 4.9 volts running through it when pressed. The problem I have is when the switch is bypassed it STAYS bypassed and the light keeps dimming up and down. Many times when I connect the remote if the light is off it will turn on and then proceed to dim up and down. When the light is dimming (when it isn't suppose to), about 50 micro volts are running through. Could anything electricity be getting through the relay (I know I have the relay put in the right direction, I did a continuity test)? I have checked for short circus with my multimeter and there are none. Is there a way to fix the problem? Possibly a resistor or voltage regulator, or a way to bring up the turn on voltage? Diode Maby???

Question by GenAap    |  last reply


is it possible to transmit audio via micro controllers? (preferably arduino) Answered

Hello, i want to connect all the stereo systems in my house (between the different rooms) so that music playing from one room can also be played in several others, maybe even more than one room to be transmitting at a time (room1>room2,room3. room4>room5 etc) i would like to have the same type of controller in each room (a box with maybe 4 inputs switchable using a 4 pos switch (like the input selection for amps), an output for the amp in that room and then some kind of digital system that selects witch room to receive audio from and then sends it to the amp via the red and white audio leads (forgot their name)) i would also like there to be maybe an lcd on the box to show where it is receiving the music from and also who is listing to the music coming from that room) originally i was just going to run speaker wire everywhere but that would have been extremely expensive.i guess the question im trying to ask is: is it possible to send reasonably high quality sound from one arduino or other type of micro controller to the other?any info at all would be great and i would be so grateful.thanks in advance - luke?is i

Question by ljarrald    |  last reply


Can you attach a micro inverter after a ups to stop feeding back into the grid ?

I have a couple off ups set up so that they use solar to charge a battery bank and use that power before switching onto the grid (basically in reverse to how they should work). now id like to take some off the load off the inverter and use micro inverters to add to my inverter however i am not allowed to feed into the grid so if i attach the the micro-inverter after the ups would it feed into the grid when the ups is in grid mode or would it only power devices attached to the ups ?

Question by Kieren-J    |  last reply


I there a way to play a cd on a CD-rom drive, and listen to it without the support of the computer?

 And if if an be possible, is there a way to monitor and control it VIA micro-controller or analog switches? also the same question for a DVD-rom drive

Question by stormsirens2    |  last reply


How to use & wire relays, speed controllers, timers, micro switches, etc. with a DC motor.?

I would like to use a 110 volt, 1/2 hp (more or less), DC ( or AC ) reversing motor to move and close a horizontal, heavy (approx. 200 lbs.) fabric, thermal, curtain blanket and then to move and open back the blanket in a greenhouse. There are very expensive commercial greenhouse systems that exist to perform this task. Since I have a hobby greenhouse that is 30 ft. wide by 80 ft. long by 13 ft. tall, I need a much more affordable system. Horizontal wires or very large monofilament fishing line  (spaced 12" to 18" apart)  will run the length of the greenhouse at approximately the 8 ft. height. These wires or lines will be used to support the blanket and for it to slide on (the blanket will have grommets or similar devices used on a shower curtain to  keep the blanket running straight, etc. ) when mechanically closed and reopened. My idea is to use a DC or AC motor to perform this task with modifications to work in the greenhouse. The motor will consist of the 110 volt, 1/2 hp (more or less), DC or AC reversing motor, that will be connected to a small cable drum spool on the motor shaft, The motor  can be attached at one end wall of the greenhouse at 8 ft. high below or above the blanket and at the other end of the greenhouse also will have a cable drum spool with a pipe for rotation an be appropriately attached to the end wall. Attached to these 2 cable drum spools would be say 175 ft. ( 2 x 80 ft. plus initial amount on spool) of say 3/8 inch aircraft cable. The curtain blanket will have a say a 30 ft. long 1/2 inch or so horizontal metal bar or pipe attached to it on the leading edge. The aircraft cable will be attached to the blanket bar or pipe.The other end of the curtain blanket will be attached to the non motor end wall. As the motor turns the 2 cable drum spools  by wrapping and unwrapping the aircraft cable, the attached curtain blanket will be pulled the 80 ft. length of the greenhouse in each direction. What I want to accomplish is as follows:                                                                                                                                                        . 1. Be able to slowly, if possible, (say over 20 - 30 minutes) close (move forward) the blanket with the motor at a preset time in the evening and for the motor to stop when the blanket is fully pulled to the motor end of the 80 ft. greenhouse. 2. Be able to slowly, if possible, (say over 20 - 30 minutes) reopen (move backward) the blanket with the motor  at a preset time in the morning and for the motor to stop when the blanket is fully pulled back to the non motor end of the 80 ft. greenhouse. To accomplish this, this reversing DC or AC motor will need to reverse direction to reopen the blanket.                                                                                      3. The shaft of a motor will probably be too short to clamp a cable drum spool to. How do I attach the spools?                                                                                         4. What is best to use a DC or AC motor? I tried extensively to research on the internet how to accomplish the above, but everything described similar processes in vague and technical terms of using various types of electromechanical timers, electromechanical relays, limit switches, microcontrollers, MOSFET circuits, transistors, arduinos, bridge rectifiers, etc. I have no  knowledge of all of these electronic devices and am totally confused. However, I am pretty good at say basic home electrical wiring. The closest thing on the internet to what I am trying to accomplish is an automatic chicken coop door, but not enough specifics for my project. I need some very, specific steps, specific products and where they can be purchased to be able to accomplished this. What type of motor, types of electronic devices, etc. Also, since it appears I will need a timer, a speed controller, relays or limit switches, etc. how in the world to  wire these to the motor in laymen terms. Thanks so much for anyone that can help me!!!

Question by woodwardfarms    |  last reply


How to limit A/C current draw from gird and draw power from secondary grid tied solar inverter ?

Micro grid tie inverters are an excellent power source and can be linked together to generate energy, however they do not function when grid is down, this is for the safety of line workers. In a real world scenario I want to ensure that all power is drawn from the energy produced by the micro solar inverters as the primary source while it can produce power and not from the grid which will act as a secondary power source, this will require some sort of current limiting solution from the grid without reducing the voltage to keep the inverter working.   For the safety of line workers I would like to have an automatic transfer switch which will have both the primary power source from grid and a tertiary inverter backed battery backup so that when the grid is off, the power is drawn from the Inverter and there is no power fed back into the line keeping lineworkers safe and since pure sine wave produced by the inverter can activate the grid-tie inverters and it should theoretically increase the VA of the UPS to the size of the installed Grid-tie micro inverter capacity, the automatic transfer switch should take care of switching between grid when power is on and to the backup inverter when power is off.  TIA for any advice in this regard !

Topic by Ruben GeradM    |  last reply


Controlling 9 Micro Servos with Arduino & Ultrasonic Sensor

Hello! I'm new to Arduino and trying to build a series of moving cogs attached to micro servos, which are triggered by an Arduino controlled Ultrasonic Sensor. My code so far looks like this #include #define trigPin 12 #define echoPin 13 #define CONNECTED_SERVOS 9 // macro just adds two - the first servo is attached to digital pin 2, this gives us upto 12 servos - digital 2 to 13 #define SERVO_TO_PIN(x) (x+2) Servo myServos[CONNECTED_SERVOS]; Servo myservo; void setup() {   Serial.begin (9600);     pinMode(trigPin, OUTPUT);   pinMode(echoPin, INPUT);     // attach the servos   for(int nServo = 0;nServo < CONNECTED_SERVOS;nServo++)   {     myServos[nServo].attach(SERVO_TO_PIN(nServo));   }    } void loop() { int duration, distance,pos=0,i;   digitalWrite(trigPin, LOW);    delayMicroseconds(2);   digitalWrite(trigPin, HIGH);   delayMicroseconds(10);   digitalWrite(trigPin, LOW);   duration = pulseIn(echoPin, HIGH);   distance = (duration/2) / 29.1;    Serial.print(distance);    Serial.println(" cm");   for(int nServo = 0;nServo < CONNECTED_SERVOS;nServo++)   {     if (distance >0 && distance < 30)   {      myServos[nServo].write(180);   }   else{     myServos[nServo].write(180);   }      }          But it isn't really the code that I am having a problem with. I know that I need an external power supply for the 9 servos but I am having difficulty figuring out what is best. I have tried attaching a 9V battery to the power and ground lines of the servos and it hasn't quite supplied enough, only making them move a little when i get closer to the distance sensor, then jittering about a bit before completely stopping. I have got a Switching Power Supply plug that has an output of 12V which I can use and plug directly into the Arduino? I also have voltage regulators that have an output of 5V available. Could somebody recommend how to wire these supplies up for the servos? Any help would be much appreciated!  Thanks

Topic by j_olo    |  last reply


Make picooz micro heli controller run from ac/dc adator

Hi all, this is my first question so bear with me.... I want to mod all my micro heli transmitter/chargers to run of a 9V dc power adaptor, I'm tired of changing/charging batteries for them and seen as I sit next to a power socket when I fly this is the best option. For this question I am focusing on the picooz sidewinder remote. What I have planned is to use a dc barrel or 3.5mm jack socket, connect - to the battery - on the pcb and connect the tip to +in on the pcb the switched tip to the battery so that when nothing is plugged in it automatically runs from battery. what I would like to know is... where to add a capacitor and what rating, this to provide enough power for the fraction of a second when the plug is pulled out, without this I would have to "trim" the controller each time because it would turn off for that small amount of time and forgotten where it has been trimmed to. thanks in advance. ps once I have this working I will be doing a full Instructable on this subject.

Topic by Djdavies83    |  last reply


Battery power and power consumption help!

I have a geocache project and need help with the power supply and power consumptin inside it. The basics of the project: It is a large wooden box. The box has a on/off switch. It also has various various coin slots. Flip the switch, turning it on, to supply power to the solenoid inside. Dropping a coin through the correct slot will trigger a momentary micro switch which activates the solenoid and springs out the drawer of treasures. Take your loot. Close the drawer. Turn off the switch and leave it for the next adventurer. And it works! Yay! Commoonents the question:  The solenoid is a 12v  door latch solenoid. https://www.adafruit.com/products/1512 The battery is a 12v 5ah sealed lead acid battery.  The coin micro switch is: https://www.adafruit.com/products/820 My question. This geocache that lives, protected, about 3 blocks from my house. I obviously won't be charging the 12v battery very often. Since this setup only has momentary power draw once in a while. Say once a week. Maaaaaaybe. Does anyone have any alternate power recommendations? I am okay with changing out the batteries once in a while. But I'm hoping for a once every few months. I originally used a new lead acid battery but it seems to have died. Possibly from letting the charge fall to low and then sulfation occured. I'm considering using a 11.1V Lipo Rc battery instead so I can recharge it at various levels of depletion. Thing is I need it to last a worth while amount of time without loosing power but also killling the battery from just sitting there.  Thoughs woukd be GREATLY appreciated.  -McG

Question by McgCache    |  last reply


how to switch on an and off a LED from my PC through RS232 ?

Hello guys,i want to switch on an and off a LED from my PC through RS232.i have developed a program in java which writes on to the RS232 port.can you help me with the circuits?? because i have zero knowledge of the circuit connection i would want to build on this project phase by phase like:1. making the one way on and off to a two sided(i.e. if i press a button on the circuit outside i get a message pop on my program telling what ever message)2. converting it to a wireless.3. then think about the micro controllerslike wise..thank you guys in advance.bye

Question by orionred11    |  last reply


Nexus 7 (2013, Gen2, FLO) - internal micro SD mod

With games getting bigger and bigger with every new release and limited storage capacity some of you might think the same: Why not add a SD card to my Nexus 7? The lates Lollipop update basically killed the normal USB OTG funstions, so if you do want to use a USB stick or external SD card in a reader you will need a powered USB OTG cable. I am not sure if this was intentionally or another bug but it is damn annoying. After openeing my tablet to check m options I realised my main problem is space. Even adding a micro SD with a similar small reader is a major pain as there simply is no empty space left inside. So I was hoping someone here might be interested in such a mod and contribute with good ideas during the build and maybe even copy the mod (if I manage it) to confirm it is in fact doable. My findings so far: A custom rom is a must have due to the OTG limits of the original. It might be enough to just find a suitable kernel but so far I settled for the Team UB Lollipop release. It offers some mods based on Cyanogen and claims full OTG support. Other roms also added support for external WiFi and TV dongles, so there is room to play. As said space is a problem I am working on ;) For an internal mod and due to the lack of physical support on the mainboard the only option is to use the standrad USB port for this mod. This means SD, reader and OTG mod must fit inside somehow. It also means some sort of physical switch is required for the times when you need full power during the recharge - although I have to test if this still works with an external SD while the tablet is switched off. In that case I could accept 500mA charge during normal use and 1A or more when the tablet is switched off. The rom should support fast USB charge but I am not sure if this olaso works in host mode. It is possible to use some extra app and scripts to make good use of such a mod. Not only can you use the SD for music, movies and other demanding files but with scripting you can also move the big data files from games to the external storage. Works similar to the apps you can get for devices with a real SD card, where you often find the "Move to SD" option in the app manager. This mod will not be for the faint hearted as it requires serious soldering skills on these tiny components, so if you only know how to solder copper pipes you might need some training on old electronics first ;) Let me know what you think and if you would be interested in such a mod as otherwise I won't bother taking pics during the progress. And without pics there will be no Instructable follwing ;)

Topic by Downunder35m    |  last reply


Anyone Have experience with Adafruit Square FSR?

I am hoping to create a circuit that will variably control the speed of a motor through pressure. If I were to wire up one of these http://www.adafruit.com/products/1075 , simply as the switch between a small motor and a power source around 5v, would it work to simply turn the motor off at rest and vary the speed with pressure? Is there a way to use this resistor as a "switch" without using an Arduino or  other micro controller? Any help is appreciated. Thanks! 

Topic by Flashflint    |  last reply


Micro LEDs... How can I power them in the smallest footprint possible???

Hi - I've been a "member" for 5 years now, but unfortunately never submitted projects... I'm more of an observer than a teacher :) I have this project I've been thinking of for quite some time now, but I simply cannot come up with a way to make it real. It's pretty simple, I just want to be able to light up an extremely small LED in a very small amount of space. But, I'm finding the power source is the headache. I wanted to get input or suggestions from anyone willing to share/help me! Basically, I have a 5mm diameter space (x approx 7mm high) to work with... and this would be to house the LED, power source and any type of on/off control or switch. My initial thoughts were toss in a micro LED, run it off of a wireless coil or super small battery and control it with a magnetic latching switch for on/off control. But, since the original idea popped up, it appears for wireless power the coil would need to be too large to fit in this space. For battery power, I've found very small 1.5V watch batteries that I could stack in a pair for 3V, but I've learned they would likely only run an LED for about 15-20 mins before they'd die. If they were wireless, I'd want some free range of motion and distance on the LEDs, being able to light up at least 6 ft. or so from the power source, if possible. This is driving me crazy! Can it be done, without costing a ton of money to develop?

Topic by djc311    |  last reply


Looking to control a motor position using a variable resistor and Arduino uno - it is not a servo?

I am a Radio ham and want to upgrade my rotator to electronic control instead of switches see http://www.qsl.net/zl1bpu/MICRO/ROTATOR/KR-400%20Schematic.gif as to what im trying to control - Need to create a c  programming type to make it simple

Question by m8    |  last reply


Mystery Contraction ? Answered

Hi all,  I found this contraption today at the tip and was wondering if anyone knew what it might be?  It has been hand-made and looks like it measures something but I can't work out what.  It has a micro amperage meter, an LED, a bunch of coils which look like they are from a heater, and also a analogue clock on top with no hands.  Oh and it also has some small glass tubes on top which look like micro movement switches. I thought it might be used to measure lightening or some other environmental effect.  Maybe earthquakes? any ideas?

Question by lonesoulsurfer    |  last reply


I'm having trouble with my sketch regarding how to code , my stepper motor traveling to a limit switch then reversing and accelerating to another limit switch.

I'm having trouble coding at a point, I built an Equatorial Platform for my telescope so I can track the stars.I have a Nema 23 stepper( 1.8 * step, 200 steps per rev.) motor with an Arduino and a Easy Driver for my micro controller. My problem when I make my sketch I have the stepper motor running at 92- 104 RPM with a potentiometer to fine adjust, at this point when my platform hits a limit switch then I want to reverse the motor and accelerate it to 2000 RPM then decelerate to 25 RPM before the platform hits an other limit switch, then start the process over.How do I incorporate accelerating coding that to a certain point then decelerate motor before it hits the other limit switch. Do I need to find some timing coding ( for some length of time), before I want the motor to decelerate to hit the second switch. I don't want the motor running at 2000PM to hit the limit switch, I want it to decelerate before the limit switch. then reverse the motor again to 92 - 104 RPM. I'm a novice at coding with little electrical background. Your assistance is greatly appreciated. Jack Brockhurst e-mail jacam9803@yahoo.com

Topic by jacam9803    |  last reply


Stripping parts from household devices

Hi I want to build a lot of the things on this site but right now I cant just go and order the parts online as where I live I either get ripped of on the price of the components  or on the delivery costs the last time I ordered parts they came to just under a tenner but it still cost me nearly 50 quid to get them in my hand so I'm looking for some advice on what kind of devices I can get different parts from the ideal thing would be a site that has a vast list of devices and what kind of components would be inside but I think such a site is very unlikely so hopefully somebody here can help me with the ones I'm looking for now I want some servos and micro switches. I have striped two microwaves for the micro switches but they didn't have the kind I was looking for the activater (sorry can't spell) was a push button rather than the lever and striped a few things for the servos that I figured would have them but they were just normal motors with cogs set up to act as the gears what I'm looking for an actual servo. I have no RC cars left as they all had the set up I just said so any thing else that you can think of that would have them in a normal house with a crap load of kids toys Thanks in advance Pacina

Topic by pacina    |  last reply


Remote Keyboard Keys Question? How to press specific keys while keyboard is locked in a cabinet?

I'm working on a children's museum grocery store exhibit where I'm using real grocery store check out scanners to "check out" fake groceries. I'm using an off the shelf program (converted by our local grocery wholesaler) and the children will be required to use a computer keyboard to operate the scanner, but only one or two buttons. The snag that I'm running into is that five-year-olds love to pry up the keys and pound on buttons. What I'd like to do is replace the keys with arcade-style micro switch buttons that could be mounted on the counter top while the actual keyboard remains in the locked cabinet below. But without programming experience or much electronics experience, I'm not sure how to go about it. Does anyone know of a simple and durable solution to remotely press keyboard keys?

Question by WaffleM    |  last reply


Will this work- 220 VDC 4A power supply - Help Reqd.

I need to generate 220V DC rectified from mains with suitable capacitor. I need to load my four micro switches in parallel with 4A load (with each node 1A). Can anybody help me choosing the values of capacitor and the diode for 4A. I've already blown off the Diodes BY127+330mfd which i used to connect earlier with 1A load. This is for testing the contact resistance of a given micro switches.I need to run these tests for a full day. I'd appreciate some immediate help... thanx in advance guys...

Topic by chuppandi    |  last reply


I'm an English Major, I want to be an Engineer, Currently Peace Corps

Hello Makers I am an English Major, I like making things, particularly micro controllers. I really want to be an engineer. Has any one made the switch from Humanities undergrad to engineering grad school? Or some kind of tech post grad? I really want a job doing working on technical stuff doing problem solving. Right now I'm in the peace corps working with Agriculture, I have been thinking of using my experience to work with irrigation for small farmers, and micro controllers. Any advice? thanks

Topic by eddieobrien    |  last reply


What are the basics of power supply mechanics to voltage and RPM's in micro vibration motors?

I'm trying to make several different versions of vibrating plush toys so I can find out what the ideal vibrating feeling will be for toddlers and babies. Too high an RPM can be scary to a little kid. I'm a beginner with little/no knowledge of basic electronics, but a capable tinker and solderer. I'd like to understand the basic logic of power supplies to micro motors and how to arrange the basic wiring. I've seen lots of instructibles but I can't find a simple explanation of this kind of thing. I've got a Radio Shack 3VDC vibe motor. no-load speed is 16K RPM. I tried wiring it to a two-AA battery enclosure (2x1.5V=3V?) and it wouldn't run. Touched leads to a 9V and it powered up but RPMs are way too high. Some related questions: 1. Can you vary the voltage to a typical micro motor and get different RPM's? 2. What's no-load speed and do I need to worry about it? 3. What kind of switch can I use to power on/off 4. How do you tell what kind of battery config to use with a motor

Question by beekhay    |  last reply


CPU/555/mini chip circuit and coding help? Answered

CPU/555/mini chip circuit and coding help? You can probably tell I don't really know what i am looking for, I have a micro-switch and a 12v dc pneumatic solenoid (for air pipe valve) I need a cpu device to say, every time power is received, no matter how long short or even if I don't release the switch at all, wait a fraction of a second or so then release 12v dc for x amount of time (to the solenoid). What parts do i need for this and how will I program it? Thanks in advance, -Digital

Question by Digital Flame    |  last reply


How do I choose an optocoupler/transistor? Answered

There are 2 circuits,one is a clap switch which provides output to ground voltage as 12 volts,and with a resistor,I managed to get an led to turn on each time I clap.I wanted to interface it with a clock which shows time when a button is pressed,but the problem is the button(marked as "show") isn't connected from microcontrollers  pin to vcc but from micro's pin to gnd (find attachment for reference).so I wanted to chose an optocoupler or transistor,but being a school student,I haven't  learnt about them,though I know how to connect them. also,please suggest some method (transistors or optocoupler & which one) to increase the number of output leds without overloading the micro Please help

Question by Suraj Grewal    |  last reply


why use a transistor when i can use the I/O pins of an ardunio

I keep seeing explanations of the uses of transistors for electronic projects. but i dont understand why i would for example: use a npn as a switch for an LED when i could just program my ardunio to use to turn it on and off again? or use any micro controller for that matter. thankyou in advance for your help im still new to eltronics

Topic by JoshuaH171    |  last reply


circuit troubleshooting help

Hi- First on an unrelated note, does anyone besides me see "A fatal, non-recoverable error has occurred" over on the Makezine forums when you try to sign in? I've been getting that for weeks! Anyway... I'm working on a variable power supply that uses a 317 to regulate the 18 volts coming from a laptop switching supply. There are two 5k 10-turn (for precision) pots with a switch so that you can have two "preset" voltages and switch between the two of them at will. There's a single output. There's also a little lamp (I used a micro mini 12v lamp instead of an LED because that's what I had) that goes on above the pot that's currently switched in. The circuit I built (schematic is below) seems to work more or less fine. 'cept there's two strange issues: First, although the pots are linear (not sure if that would make the difference or not), they seem to "flatten out" toward their upper range. The first six turns gets you from 1.2 to about 16.5 volts. Then the last four turns either don't change anything or they do so in _very_ fine increments so that you only get from 16.5 to just over 17 volts. That's in four whole turns of the knob. This happens for both pots. The second stange thing is that turning the non-activated pot will affect the current voltage. When you increase the resistance (turn the knob to the right), the voltage level actually drops! Conversely, turning it to the left will increase the voltage. Remember, this is the switched-off pot. The switched-on pot works as it should (barring the mentioned weirdnesses). It looks like how much the voltage changes depends on how many turns you've given the activated pot. I suspect this has to do with me using a SPDT switch instead of a DPDT and maybe some voltage / current bleeding through the lamps and into the adjust pin, or something. But I ca/n't figure out why the switched-off pot would do anything. Anyway, take a look at the schematic. Is there anything I've done wrong that I'm missing? Should I, um, switch (*cough*) to a DPDT switch (something like the second schematic)? I used the SPDT cuz that's what I had. Anyy help is appreciated, Thanks!

Topic by deadbilly    |  last reply


Wiring 2 pots together?

Ok, so I am in the hobby of hobby grade rc. I am currently working on modding a ps2 racing wheel and foot pedals to work with a spare 2.4ghz remote I have for my cars. I got the steering wired up fine and it works good. Now for the somewhat tricky part. The foot pedals each have a potentiometer in them. They share ground and power, and have separate signal outputs. I have the right one wired in for the throttle just fine. On my micro car it was easy enough, just switch the throttle reverse switch and push the pedal and it goes in reverse. But most escs wont calibrate to that. How would I go about wiring them together? essentially I want to turn 2 pots into one big pot. So when I push the right one down it sends the signal for forward. When I take off the right one and push the left one down, it signals reverse. I could bring my micro controller into the mix, but I really dont want to for something that seems so simple. Plus it is on a serb right now. Any help?  Thanks

Question by TOCO    |  last reply


Convert AAA battery power to 12V jack?

So I figured out a really good option for my external rumble pack I want to make, I see these Wii lightguns use X2 AAA batteries and have a micro switch that engages the internal rumble motor on the handle of the gun. The batteries are connected to a microswitch and the switch is pressed after the trigger is physically pulled. How can I convert the AAA batteries power method into an external 12V power connector for continuous use and stronger motor vibrations etc? Like I said this is my first DIY thing. I want the AAA battery method to be converted to a stronger more capable 12V. I plan on buying some strong force feedback motors that need 12V. Eventually adding a small Solenoid too.

Topic by JonathanH248    |  last reply


My Arduino board affected by opening or closing any key to open any lamp in my house

i am an Amateur in electrical engineering  i learned a few thing  about micro controllers and i mad a project this project about light switch trigger by laser the project Component of 1- Home made Arduino board 2-home made relay module 3- home made voltage regulator 4-tow 5V 1A adapters 5- laser 6- photo resistor   the voltage regulator  take the power form the first adapter to supply 4.8V to the voltage regulate to out 4.8V to the laser and the laser pointed to the photo resistor and the adrduino board take the power from the second 5V adapter  looping on when the photo resistor value less than 750 then switch the relay module to high and delay the code for 10000 M Seconds and then switch the relay to low and end that is the project    BUT........? when i installed this project to the real live on stairs fluorescent lamp .... first it takes a while to trigger the relay switch  and the biggest problem i do not know why  when i open any near by switch to open or closing any of my hows lamp its trigger the relay on and then the rest of the code  continue normally not this only also when i insert any near by plug its look like some how connected to electricity   I Rely Do not know the problem where  and the schismatic for adrduino board , relay module and voltage regulator attached cold any body please help me

Topic by i_sadek    |  last reply


Arduino joystick to act as 2 joysticks

Hi guys hope some 1 can help me out I've made a 3 axis joystick for my computer using an arduino Pro micro which works perfect however ide like to be able to flick a switch which would then make that joystick work as another joystick so would turn a 3 axis joystick into 2 3 axis joysticks if that makes sence I've seen it done but can't find any info on how to wire it or how the code needs to be altered as I'm new to coding so not the best any info would be greatly appreciated thanks

Topic by LurcherK981    |  last reply


How do I make a power indicater light for a bluetooth?

I have Bluetooth headphones, & I'm modifying them. I want my Bluetooth to light up tow external LEDs when I turn the device on. I can't wire a line to the micro LED, its to small for me to solder. I was thinking wiring the External LEDs to the Bluetooth's battery. Is there a way to make a simple connection from the battery, to the external LED wire & back to the circuit board, so when ever the Bluetooth is switched on, all the external LED is indicating is the power going to the circuit board?

Topic by elkaddalek    |  last reply


building a HD Audio front panel for my PC. Audio circuit?

Hi! I have problem with my computer. the motherboard has HD-Audio but the front panel is the usual AC97 standard. You can change the BIOS config so the front panel audio connector acts as an AC97 one, but then the problem is the speakers connected to the back keep playing even if you connect a set of headphones to the front panel. The reason is the audio jacks used for HD-audio are different from regular jack connectors (and very rare to find!). While the insertion of the plug in a regular jack connector results in breaking a circuit (and so, physically muting the loudspeakers), in an HD Audio jack, the insertion of the plug results in closing a switch (sending a signal to the driver ordering to mute the speakers by software). I managed to create a sort of HD audio Jack by combining a regular jack connector and a zero pressure micro-switch so when the plug enters the hole, a tip inside the hole closes the micro-switch. I wanted to make a good quality front panel so instead of just wiring the jack connectors (and micro-switches) to the cable, I decided to add an EMI filter. I took the circuit from this doc: http://www.formfactors.org/developer/specs/A2928604-005.pdf and more precisely from fig 6 at page 25. The circuit uses two 220 pF capacitors and two inductors for each jack connector. In this aspect the circuit is identical to that proposed for AC97. The problem is I have no idea what inductors to use or how to ask for them at the shop. All the diagram says in a footnote is: ZL should be 600 Ohms or greater @ 100MHz with a low Q (broad Impedance curve over frequency) but not even the guys at the shop knew what piece to give me. So what I did was to cannibalize the inductors from two cheap promotional radio receivers with jack connectors for the headphones and use them for my circuit. After all, they perform the same function: filter the audio signal at the headphone connector so I supposed they should have the correct values I needed. But my circuit is very noisy! headphones have a constant electronic background noise (that seems to react to things like mouse movements, hard disk activity or whiteness of the screen) and microphone has a lot of noise (of course I'm using very good quality mic+headphone). The cables are audio cables for front panel audio so they are supposed to be correctly shielded so the problem is in the circuit at my custom board. I would like to make a tutorial (including HD Audio connector construction) once the front panel is working properly but I don't know how to fix it. Any ideas?

Topic by jedikalimero  


This arduino code does not work as expected, any help? there seems to be an issue with the digitalWrite function. Answered

Recently, I wanted to make a laboratory grade linear semi-precision power supply using an Arduino, LCD, some comparators, and MOSFETs. Idealistically, I want measurements to be 3 significant figures of precision (0.1% accuracy @ 30V), voltages as high as 30V, and max current of 10A. The power supply is most likely going to be just a single regulated output, maybe if I feel lucky I will make 2 regulated outputs once I get the darn Arduino code to work. The Arduino's job is to simply set and read the output voltage, and is not part of the control loop. That is what the comparators are for. (I learned the hard way that using the Arduino within the control loop just results in parasitic oscillations because the Arduino is a clocked device and can only self correct at timed intervals.) Anyway, below is the code. I made explanations of all portions of it as clear as possible, and I also give the wiring used for the LCD, 4 buttons, and analog inputs used to set and read the voltage and current. However, the issue arises when I upload the code, the setVI button does not work unless I press both it and the RS button at same time. I made the many of the integers display in the serial output to diagnosing easier hopefully. I can see the setVI integer and my dudd integer only goes HIGH when  either it and the RS buttons are pressed simultaneously, or when the RS butten is held down for a long enough time. However, as far as I am aware, nowhere in the code do I manipulate that code so setVI goes HIGH dependant on other buttons, so I am bewildered by this parasitic phenomenon. Is my Arduino MEGA broken? I had a similar problem in the past, where I had multiple analogRead statements It strangely seemed to factor in the outputs of other input pins. Anyway, here is the code. Maybe someone could upload it and tell me if it functions properly on their arduino? That would help me determine if it is indeed a software issue. (p.s. I use an Arduino ripoff called the Funduino, but it is not broken in any way, I don't think?) Any and all help would be greatly appreciated, thank you in advance, -Max-. p.s. To make the code below legible, please copy/paste it in an IDE or in notepad and convert it into a monospaced font, it will make it very easy to follow. //---------------------------------------------------------------------------------------------------------------// /* Arduino Software for lab power supply. Wireing guide:        **Wiring for 16x2 LCD:**       * LCD RS pin to digital pin 12       * LCD Enable pin to digital pin 11       * LCD D4 pin to digital pin 5       * LCD D5 pin to digital pin 4       * LCD D6 pin to digital pin 3       * LCD D7 pin to digital pin 2       * LCD R/W pin to ground       * 10K resistor:       * ends to +5V and ground       * wiper to LCD VO pin (pin 3)    **Wiring for buttons:**       * RS       button to pin 6  (as a digital input) -- Switches from reading read current/voltage values to setting those values, and Vice Versa.       * VIselect button to pin 7 (as a digital input) -- Switches to the 'set' mode and flips from setting the voltage to setting the current.       * UP       button to pin 8  (as a digital input) -- Increments the voltage or current up when in the 'set' mode.       * DOWN     button to pin 9  (as a digital input) -- Increments the voltage or current up when in the 'set' mode.    **Analog inputs/outputs:**       *A0   -- Measures a potential of a resistor divider that can output a voltage of 0-5V based on the 0-30V output this PSW capable of.       *A1   -- Measures the current flow through a resistor to measure current. (Some reason there seems to be a pulldown resistor on this pin, so the voltage does not float.)       *Vout -- This will be later implemented if I get a DAC, for the increased resolution. (1024 is just not enough in my opinion. At least 12 bits)       *Aout -- This will be later implemented if I get a DAC, for the increased resolution. (1024 is just not enough in my opinion. At least 12 bits) */ int UP    = 0;      // These are the 2 buttons used to incrementally int DOWN  = 0;      // step up or down the voltage on the output int RS = 0;         // These 2 buttons tell the LCD to either read out the voltage on the analog pins. (I plan to change this so it reads from a 14 bit ADC and writes int setVI = 0;      // the voltage output through a 14 (or 16 bit) bit ADC. I need 3 significant digits, or at least 0.1% accuracy. int dudd = 0;       // this dudd (dummy variable) is just here to prove that digitaslreading pin 7 works very weird! Any help on this? int preRS = 1;      // Anything with a "Pre" before it is simply what said integer/variable on the last loop. I use these to prevent a parasitic int presetVI = 1;   // oscillation of states that they control, so when a button is pressed, it will not jump between 2 states every cycle. int preUP    = 0; int preDOWN  = 0; float Aset = 0.00;  // I need these to be "floated" so I can set the exact value of these to 3 significant digits. float Vset = 0.00;  // Aset and Vset define what the output voltage *should* be, and are defined with the UP/DOWN buttons. int VIselection = 1;// this variable will invert when Aset button is pressed. Similar to the IVselect, this number will also invert int READorSET = 1;  // Bset button is pressed. This allows the mode to be changed from SET mode or the READ output mode, thus allowing                     // one to compare the output voltage and current to the set value, as well as set the output voltage and current. #include LiquidCrystal lcd(12, 11, 5, 4, 3, 2);// initialize the library with the numbers of the interface pins void setup() { //-------------------------// I tried making diagnosting this thing easier by making all the important data availible in the serial monitor.   lcd.begin(16, 2);   Serial.begin(9600);   Serial.print("INPUTS         RS:           READorSET:       setVI & dudd:        VIselection:");   Serial.println(""); } void loop() {   float V = (30.00*analogRead(A0))/1024.00;   //These are what I use to read the voltage output of my power supply. I will have a voltage divider on the output,   float A = (15.000*analogRead(A1))/1024.000; //to limit the voltage range from 0-30V to 0-5V. Same concept goes for the current measurement.   int dudd  = digitalRead(7);//   RS    = digitalRead(6);//RS stands for "Read/set"   setVI = digitalRead(7);//VI is stands for "Current/Voltage set"   UP    = digitalRead(8);//UP is simply a button used to set voltage & current   DOWN  = digitalRead(9);//DOWN is simply a button used to set voltage & current     if(presetVI == LOW && setVI == HIGH){VIselection = -VIselection;}   if(preRS    == LOW && RS    == HIGH){READorSET   =   -READorSET;}     Serial.print("\t        ");  // prints an inital space.     Serial.print(RS);            // prints the RS reading. It should be '1' when pin 7 is HIGH.     Serial.print("\t        ");     Serial.print(READorSET);     // prints the READorSET reading. This should only change when the RS button is pressed.     Serial.print("\t        ");     Serial.print(setVI);         // prints the setVI reading. It should be '1' when pin 7 is HIGH.     Serial.print("\t");     Serial.print(dudd);         // prints the setVI reading. It should be '1' when pin 7 is HIGH.     Serial.print("\t        ");     Serial.println(VIselection); // prints the VIselection reading. This should only change when the setVI button is pressed.         //if(presetVI == LOW && setVI == HIGH && READorSET == 1) {READorSET = -READorSET; VIselect = -VIselect;}      // This line of code just makes so that when I need to go from the voltage read screen to      // the set mode, I can just press the VIselect button. It just makes things more intuitive, but could be      // causeing the error, so I nulled it. I also nulled it out another portion that will keep the voltage or      // current setting the same when using the VI buttton to select the set mode. (otherwise it has to be      // double pressed to return to, say, the current setting, if that is where you left off.)   if(UP == HIGH && DOWN == LOW && VIselection == -1){if(Aset <= 10.00) {Aset += 0.05;}}   if(DOWN == HIGH && UP == LOW && VIselection == -1){if(Aset >= 0.10) {Aset -= 0.05;}}     if(UP == HIGH && DOWN == LOW && VIselection == 1) {if(Vset <= 30.00) {Vset += 0.05;}}   if(DOWN == HIGH && UP == LOW && VIselection == 1) {if(Vset >= 0.05) {Vset -= 0.05;}}     if (RS == HIGH){digitalWrite(13, 1);}   if (RS == LOW){digitalWrite(13, 0);} //============================================================================================================//   if (READorSET == 1){      //this is the defualt screen, and shows the output voltage and current.     lcd.clear();              lcd.setCursor(0, 0);     lcd.print("VOLTAGE:");     lcd.setCursor(0, 1);     lcd.print("CURRENT:");     lcd.setCursor(10, 0);     lcd.print(V);     lcd.setCursor(15, 0);     lcd.print("V");     lcd.setCursor(10, 1);     lcd.print(A);     lcd.setCursor(15, 1);     lcd.print("A");   }   if (READorSET == -1){   // This is the portion of the code allowing me to set the current and voltage     lcd.clear();          // using the up/down buttons.       if (VIselection == -1){         lcd.setCursor(0, 0);         lcd.print("  SET CURRENT:");         lcd.setCursor(5, 1);         lcd.print(Aset);         lcd.print("A ");       }       if(VIselection == 1){         lcd.setCursor(0, 0);         lcd.print("  SET VOLTAGE:");         lcd.setCursor(5, 1);         lcd.print(Vset);         lcd.print("V ");       }   } //============================================================================================================//   presetVI = setVI; // At the end of each loop, the current variable settings that were used are set equal   preRS = RS;       // to the 'pre' versions of the code. This allows me to basically measure the when                     // the button is initially pressed, and/or released. Using this method with the delay()                     // function, however, is a bit buggy, but I did have it working well enough before. If you                     // tap the button too quickly. You almost have to hold it for a split second. If you                     // know a better, simpler way of doing this, please tell me, thank you.                       delay(80);        // The delay helps stabilize the reading on the LCD, but if it is too large, than the                     // refresh rate suffers, and the buttons respond slower. However, setting too low will                     // cause the reading on the display to change so rapidly, it is illegible. }

Question by -max-    |  last reply