PSU bench power supply

My PSU appears to have blown up over the christmas holidays- it was a bit unreliable before, but now it won't boot up my computer at all. I replaced it with a spare from work which works fine, so I now have a not-working 400W PSU I'd like to make a bench power supply from, that will hopefully kick-start my desire to get into microcontroller programming. Does anyone know what the chances are that a broken PSU (no sign of magic smoke, it just doesn't power my computer any more) will still be working enough to use as a DC power supply? If it is, the 'Ibles sometimes disagree- what is the accepted way of keeping it turned on (short a pair of wires, attach a resistor across a pair etc)? It's a 20-pin connector with square 4-pin aux and the usual complement of molex.

Topic by PKM   |  last reply

Is it possible to convert bench drill machine to automatic drill machine ? Answered

Please if some one can help and guide in detail , thanks in advanceI have this type of bench drill machine 1, I want to convert it to double chucks2, so that it can hold two drills3, I want to drill diameter 4mm, depth 5mm in two pieces simultaneously 4 I want to put some sensors so that drill bit( dia 4mm) should automatically go deep to 5mm After touching the job surface and then should go up again so that we can put another same job again5 It should also sense the load the drill bit is having while drilling and it should stop automatically when the drill bit has certain higher load so that it can be re grinded and re fitted again Thanks In advance

Question by Singh   |  last reply

Turning on an old Psu

Hey there, I got this old PSU, a Delta DPS-350EB-3 from an HP NetServer. I'm trying to make a lab power supply out of it, i just can't get it to power on. There's a blue wire bundled with a ground that when shorted will power the psu for a second then shut it back off.  I tried to put a load on the 5v & 12v with no success. Anyone got an idea? Thanks

Topic by wbzial   |  last reply

Bench power supply potentiometer for 20v?

Hello! I am trying to build a bench power supply from a laptop power supply and i need a potentiometer capable to handle 0-20v. I have tried many times with different potentiometers but they all start smoking and later starts burning :( i don't know that much about elektroniks circuits so be gentle :) Please help me!

Question by WaNa_Cookie   |  last reply

Shop made bench power supply.

Hello I have an atx dual sata 550 watt power supply... I have seen a bunch of instructables on here that allow just a few different voltage selections.. I have also seen a few with potentiometers to allow it to be more adjustable (dial up or down the voltage). That is what i want, i dont want to be limited to just three different options. S my question to you is, what type of potentiometer do i need to buy for this? And will a regular autostore purchased dashboard voltage meter window work? Also, what type of fuse/or breaker should i use?. Do i even need one? I also head i need some kind of "switch" for this as well. I found circut diagrams, i found list of items needed, but most of the instructables ihave found arent very specific on the specs of these extra items needed... Any help or direction would greatly help. Im going out to radio shack today and would love to grab the items needed to finish this priject. Thanks all...

Topic by SlickSqueegie   |  last reply

Powering a multimeter built into bench-top power supply?

Recently I built a bench-top power supply from an ATX power supply (Like the one from here: It works great but I'm looking to consolidate this and my analog multimeter into one box. I'd like to know how to power the multimeter using the power supply so I don't have to worry about changing the batteries. The multimeter uses two AA batteries and a 9V, and the power supply has voltages of 12, 5, 3.3, 0, -5, and -12. Thanks for any help.

Question by ranab998   |  last reply

continuity between 3.33v and gnd on atx psu?

Im converting my atx into a bench psu. I was checking the continuity between 5v and gnd that i connected to the LTC3780 and i got a beep (one short beep). So i checked the rest of the lines and 5v and 12v also 1 short beep. However on the 3.3v. i get  a long continuous beep. Is this behaviour to be expected?  thank you in advance.

Question by icey.hood   |  last reply

Combining PSU rails for lab power supply? Answered

I recently received 2 old computers from friends for tinkering purposes. I'd like to take their PSUs and create a power supply for projects. However, they only have max outputs of 110W. So, I have a few questions: 1.) Is it possible to combine rails? 2.) Is it safe? 3.) What kind of power increase would I be seeing? Please try to answer all 3 individually.

Question by General Eggs   |  last reply

12VDC from computer power supply WHILE COMPUTER IS RUNNING?

Okay, how crazy would this be? I need a 12VDC power supply to do some bench testing. I have a computer by my workbench which has at least one free Molex connector coming out of the PSU. I know I've seen Instructables that show how to make a bench power supply from a disconnected computer PSU, but would it be a really terrible idea to run wires out the back of the computer case to my bench and use them to test circuits? What are the potential pitfalls, and what are some steps I could take to make them less likely? I'm thinking fuses on the incoming power lines are the first step.

Topic by yoyology   |  last reply

Is it possible to wire computer PSU's in series to achieve a higher voltage? If so, how can it be done?

I want to make bench top PSU's out of old computer power supplies and I want a 24v output as well as the typical outputs, but I don't want to put a transformer on it that could only handle so much current (I might want to run some bigger motors off it)

Question by The Ideanator   |  last reply

Computer PSU wire question? Answered

Hi all, I want to turn an old computer PSU into a lab bench PSU.  After cutting all the connectors at the end of the cables, I've noticed that some of the common (black) wires were made of copper, while some of them were made of nickel \ aluminum (Silverish). The same is true for the +5V (red) cables. It's not the first PSU I noticed that had the different materials, and I was wondering: 1) Why are there two different kinds of wire? 2) Is it OK to ignore the wire material and just splice all the blacks together, and all the reds together? Thanks!

Question by Morgantao   |  last reply

ATX PSU to Work Bench PS - Adjustable Voltage and Current question

I am working on converting an old 600W ATX PSU to a bench power supply for me to use for some lab work.  Not everything that I will be plugging into it will have built in current limiting capabilities.  The guide/setup i found on here that I will most likely be following are:  & The first link is how I would like mine to end up looking. My PSU is rated as: +3.3V @ 32A +5v @ 50A +12v @ 24A -12v @ 1A -5v @ .5A My end goal is to be able to control the voltage and current output from each binding post.  I will be hooking up a multimeter to this as well and am thinking that i could control what it monitors by some dipswitch setup or switching setup(as far as to which binding posts it's monitoring). I do understand that V = IR.  So keeping 5v but only wanting 3A, i would increase the resistance which is why at first i thought i could play a POT in the circuit.  However after seeing how the voltage regulation was hooked up, I am confused how to do so now since it was connected in the fashion i thought i would need to control the current.  ( I would probably use a LM338 since it would allow for more current but again, i would love to be able to have the full 50A available all at one shot but i don't think those IC's allow for that. I am extremely new to all of this and am still learning as well, so if i was able to communicate what i am looking to do correctly and you have a way of explaining it to me, a picture would be awesome if you have the time to create one. :D TYIA for any suggestions.

Topic by agentc0re   |  last reply

Inverting 115VDC to 115VAC. 75watts?

What would be the best low cost method for me to invert 115vdc to 115vac for a low 75watts bench experiment?

Question by rpshomeservices   |  last reply

Bench top power supply with 9 volt and 1.5 volt outputs? Answered

I am buidling a benchtop power supply from an ATX power supply.  I understand using the color codes how to accomplish  12v, 5v, and 3.3v connection connection ports. How could I add 2 more power ports for 9v and 1.5 volt? Basically I am trying to minimize the use of batteries in my testing with most common power sources. I have read a little about the -12v and -5v being obsolete power options.  Is there any need for these voltage outputs for a newbie electronics hobbiest? Thanks, TRU

Question by DiyWaterDog   |  last reply

How do I wire a LTC3780 to my arduino and display?

I'm re-purposing an old ATX psu into a variable bench psu. The current project has LM2956's however they're faulty, I can only see 11.78V max instead of 29+V. The other down side to these modules is the lack of current control. The project also has an arduino Mega handling acs712 hall current effect sensors and Voltage dividers for my 3.3v 5v 12v terminals and two LDC dispays 16x2 and 16x4. So I was wondering assuming I keep the basic design of the psu can i replace the LM2956s for a single LTC3780, How can I wire the LTC3780 to the arduino and allow me to see the current change.  Thanx in advance.

Question by icey.hood   |  last reply

Adjustable Voltage on PSU ATX

I have an old Rockford P450.4 amplifier that I salvaged an LM317T and LM337T from. It also had some two (2) potentiometers that I salvages as well. I have a 400W Coolamx PSU ATX that I turned into a bench supply. I have read that people have been using these two (2) IC's to maintain a constant voltage through variable adjustment. I have seen several tutorials on instructables, but that all lack clarity, instruction and do not provide enough detail. I could really use a good tutorial, but have failed to find one of great interest.

Topic by bprins   |  last reply

12v to 120v sine inverter boosting

I have a 20 year old van. The a/c leaked and it is much cheaper to buy a 120v window unit ($140 with a 3-year walk-in exchange warranty) than to pay a shop to rebuilt the vehicle a/c. I chose a 5k BTU window unit that uses 4.1 amps running, and have a 1k watt sine wave inverter. Alone, the inverter will not start the a/c unit, but will power the fan. I confirmed a trick to start motors with an inverter. I connected an 8" bench grinder to the inverter and started it. It took a few restarts to get it up to speed. Then I started the a/c and it ran without problems. The bench grinder motor was able to supply the reactive power the a/c compressor needed to start. Both continued to run without straining the van's alternator. BUT, I don't want to travel with a running bench grinder going, that's not safe. Is there another way to supply the reactive boost that is safe to travel with? Once I get a simple stable way to run the a/c I'll work on a mount to vent the hot side. The van has sliding windows.

Topic by DavidN71 


I currently have a HP 6623A bench top PSU which is amazing to say the least but I never end up using all of the features and its pretty big. It regulates voltage and amperage but I really only need a really good variable voltage bench top PSU. What I need: 3x 0-12V 3A outputs What I have: tons of computer PSUs, wall warts, and everything in between. What I was suggested to use: 3x LM350T 3x 5k pot running off the 12V rail of a PSU. Does anyone have a suggestion for a better configuration? Is there a better variable regulator you suggest? -Thanks!

Question by newrev426   |  last reply

ATX Power Supply Help!

I have this power supply. is it an atx supply? because i want to turn it into a bench top power supply but i can only use an atx. it has a 20 pin connector. i heard that if its not an atx, it wont work for some of the ibles on here. thanks.

Topic by DELETED_DELETED_kruser495   |  last reply

Power wheelchair controller testing

I just bought a VR2 controller and I want to know how to bench test it to make sure it is functioning properly before I resale it. I do have a good multimeter.  I just need to know which studs to connect the MM leads to on the controller and what readings I should supect to get.  Thanks again for the help?  Manpan

Topic by themanpan68   |  last reply

I would like to power a 12v dc 10amp water pump with a 120v power source...Ideas???

What could I use to do this without actually buying a $100 converter...I have read some instructables on using a pc power supply to make a bench power supply...but that seems like more than I need...any ideas???

Question by wingrider78   |  last reply

Im repurposing my atx power supply to be a bench Psu. I need help with code please?

In this project. I want to use an arduino mega, 2 lcds, and 6 acs712 current sensing modules and 2 Lm2596 dc step up/down module The set up I have in mind is like so; arduino is powered by ATX stand by power (IF possible) there is a push button which turns on the programing to start the monitoring and also grounds the ATX and GReen wire to supply power to all the rails. This set up will calculate Voltage and current printting them on the lcd's. The constant voltages will be printed on on lcd and the variable voltages on the other lcd. Ive written most of the code. I just want it to make sense. I've added a picture, which my project is based on.. the difference are, im not using I2c bus for lcd, im measuring current, and im printing info on two different lcds. thanks for the help. here is the code #include #define PWROK_PIN 4 // change to w.e pin i end up using connected to green? investigate #define PWRBTN 2 // closing push buttom connection makes it high #define PWRTRANS 6 /*-----( Declare objects )-----*/ // Variables will change: int PWRSTATE = HIGH;         // the current state of the output pin int buttonState;             // the current reading from the input pin int lastButtonState = LOW;   // the previous reading from the input pin // the following variables are long's because the time, measured in miliseconds, // will quickly become a bigger number than can be stored in an int. long lastDebounceTime = 0;  // the last time the output pin was toggled long debounceDelay = 50;    // the debounce time; increase if the output flickers // initialize the libr with the number of the intface pins double sensePinVthree = A0; double sensePinVfive = A1; double sensePinVfivesb = A2; double sensePinVtw = A3; double sensePinVrone = A4; double sensePinvrtwo = A5; //The current double sensePinIthree   = A6; double sensePinIfive   = A7; double sensePinIfivesb = A8; double sensePinItw  = A9; double sensePinIVrone = A10; double sensePinIVrtwo = A11; //setting up default or naming variables. double Voltsthree; double Voltsfive; double Voltsfivesb; double Voltstw; double VoltsVrone; double VoltsVrtwo; double Currentthree; double Currentfive; double Currentfivesb; double Currenttw; double CurrentVrone; double CurrentVrtwo; LiquidCrystal lcd(12, 11, 5, 4, 3, 2); LiquidCrystal lcd2(12, 10, 5, 4, 3, 2); //remove this if not working or glitchy void checkPowerOK(){   // when green is grounded   if (digitalRead(PWROK_PIN) == HIGH) {     lcd.setCursor(4, 1);     lcd.print("ON ");     lcd.setCursor(9, 3);     lcd.print("hello");   }   else if (digitalRead(PWROK_PIN) == LOW) {     lcd.setCursor(8,1);     lcd.print("OFF");   } } void togglePower(){ static unsigned long last_interrupt_time = 0; unsigned long interrupt_time = millis(); // If interrupts come faster than 200ms, assume it's a bounce and ignore if (interrupt_time - last_interrupt_time > 500) {    // set the power:   digitalWrite(PWRTRANS, PWRSTATE); //trans is pin 6 } PWRSTATE = !PWRSTATE; last_interrupt_time = interrupt_time;  } void setup() { analogReference (DEFAULT); pinMode(PWRBTN, INPUT); pinMode(PWRTRANS, OUTPUT); attachInterrupt(0, togglePower, RISING); digitalWrite(PWRTRANS, PWRSTATE);     lcd.begin(16, 4);   lcd2.begin(16, 2); // Print a message to the LCD. lcd.setCursor(0,0); //take this out if monitor buggy lcd.print("Bench PSU");// this code be fine lcd.setCursor(0,1); lcd.print("Monitor  V1.0"); lcd.setCursor(0,2); lcd.print("ICE"); lcd.setCursor(4,3); lcd.print("ROBOTICS"); lcd2.begin(16, 2); // replace with the date_time function lcd2.setCursor(0,0); lcd2.print("Hope 4 the best"); lcd2.setCursor(0, 1); lcd2.print("prep 4 the worst"); delay(3000); lcd.clear(); // wipes old message lcd.setCursor(5,0);  lcd.print("Building the Future"); lcd.setCursor(0,1); lcd.print("since   2014"); //Inset the time function somewhere in here lcd.clear(); lcd2.clear(); //lcd.createChar(0, blockChar);     Voltsthree=0; //setting my variables to Zero   Voltsfive=0;   Voltsfivesb=0;   Voltstw=0;   Currentthree=0; //Setting current to Zero on this Lcd   Currentfive=0;   Currentfivesb=0;   Currenttw=0;       VoltsVrone=0; // doing the same but for second lcd   VoltsVrtwo=0;     CurrentVrone=0;// same for current   CurrentVrtwo=0; } void loop () {checkPowerOK(); // check to see if power ok   Voltsthree = ((analogRead(sensePinVthree)) /218.0) *5; // or 7 aalso the 218.0 value will chaange to mine specific   if(Voltsthree <0){     Voltsthree=0;   }   Currentthree =(((analogRead(sensePinIthree)) / 212.0) -2.55) / 0.6666667;// why 0.667   if(Currentthree <0) {     Currentthree=0;   }   Voltsfive = ((analogRead(sensePinVfive)) /218.0) *5;   if(Voltsfive <0){     Voltsfive=0);   }   Currentfive =(((analogRead(sensePinIfive)) / 212.0) -2.55) / 0.6666667;// why 0.667   if(Currentfive <0) {     Currentfive=0;   }   Voltsfivesb =((analogRead(sensePinVfivesb)) /218.0) *5;   if(Voltsfivesb <0){     Voltsfivesb=0;   }   Currentfivesb =(((analogRead(sensePinIfivesb)) / 212.0) -2.55) / 0.6666667;// why 0.667   if(Currentfivesb <0) {     Currentfivesb=0;   }   Voltstw =((analogRead(sensePinVtw)) /218.0) *5;   if(Voltstw <0){     Voltstw= 0;   }   Currenttw =((analogRead(sensePinItw)) / 212.0) -2.55) / 0.6666667;// why 0.667   if(Currenttw <0){     Currenttw=0;   }     VoltsVrone =((analogRead(sensePinVrone)) /218.0) *5;   if(VoltsVrone <0){     VoltsVrone=0;   }   CurrentVrone =(((analogRead(sensePinIVrone)) / 212.0) -2.55) / 0.6666667;// why 0.667   if(CurrentVrone <0) {     CurrentVrone=0;   }     VoltsVrtwo =((analogRead(sensePinVrtwo)) /218.0) *5;   if(VoltsVrtwo <0){     VoltsVrtwo = 0;   }   CurrentVrtwo =(((analogRead(sensePinIVrtwo)) / 212.0) -2.55) / 0.6666667;// why 0.667   if(CurrentVrtwo <0) {     CurrentVrtwo=0;   }   //1st line   lcd.setCursor(0,0);   lcd.print("                "); //clear the line 1st line   lcd.setCursor(0,0);   lcd.print(Voltsthree);   lcd.setCursor(5,0):   lcd.print("V");   lcd.setCursor(7,0);   lcd.print(Currentthree);   lcd.setCursor(14,0);   lcd.print("A");     //2nd line   lcd.setCursor(0,1);                  // clear and print second line   lcd.print("                ");   lcd.setCursor(0,1);   lcd.print(Voltsfive);     lcd.setCursor(5,1);   lcd.print("V");   lcd.setCursor(7,1);   lcd.print(Currentfive);   lcd.setCursor(14,1);   lcd.print("A");     //3rd line   lcd.setCursor(0,2);           // clear line 3   lcd.print("                ");   lcd.setCursor(0,2);   lcd.print(Voltsfivesb);     lcd.setCursor(5,2);   lcd.print("V");   lcd.setCursor(7,2);   lcd.print(Currentfivesb);   lcd.setCursor(14,2);   lcd.print("A");     //4th line   lcd.setCursor(0,3);           // clear line 4   lcd.print("                ");   lcd.setCursor(0,3);   lcd.print(Voltstw);     lcd.setCursor(5,3);   lcd.print("V");   lcd.setCursor(7,3);   lcd.print(Currenttw);   lcd.setCursor(14,3);   lcd.print("A");     //1st line   lcd.setCursor(0,0);   lcd.print("                "); //clear the line 1st line   lcd.setCursor(0,0);   lcd.print(VoltsVrone.);   lcd.setCursor(5,0);   lcd.print("V");   lcd.setCursor(7,0);   lcd.print(CurrentVrone);   lcd.setCursor(14,0);   lcd.print("A");     //2nd line   lcd2.setCursor(0,1);                   // clear and print second line   lcd.print("                ");   lcd.setCursor(0,1);   lcd.print(VoltsVrtwo);     lcd.setCursor(5,1);   lcd.print("V");   lcd.setCursor(7,1);   lcd.print(CurrentVrtwo);   lcd.setCursor(14,1);   lcd.print("A");   }

Question by icey.hood   |  last reply

atx power supply wrong voltages

I've done some experimenting with an ATX power supply, trying to turn it into a bench top, and I've come close.  I have 1 more problem, the voltages are off.  Instead of 5v I'm getting 5.25, instead of 12 I get 11.4 and most dramatically of all instead of 3V I get 4V. Has anyone had this problem before and learned to solve it? 

Topic by bobobano   |  last reply

PSU Power Supply

I built a PSU bench power supply, but it isnt outputing the right voltages. It just out 5v for all lines(12v,5v). It has a purple wire that is said to be the stand-by, but the psu wont start unless it is connected to the 12v or 5v line. It also says that you have to have the brown sense wire attached to the 3v wire but this seems to do nothing. How can I make this thing output the right power(12v @ 22A, 5v @ 50A)?

Topic by tylerb   |  last reply

how would you make a powernet model pwp 165h computer power supply turn on with out the motherboard?

 i am trying to make a benchtop power supply from a powernet model pwp 165h computer power supply. the power supply wont turn on unless its connected to the motherboard, and the whole computer is powered up. i would greatly appreciate any help or advice.

Question by knexer87   |  last reply

5v dc to 18v dc? (it can't be as hard as I am making it?)?

I need a step up transformer to go from my average bench power supply (5v dc) to 18v dc (the same I would get from 2 9v batteries). I have an associates in electronics but it's from 10 years ago and I can't make the information come back into my brain. Any help would be appreciated.

Question by Random Point   |  last reply

PSU shorting out when trying to power stuff?

I'm trying to build a bench top psu from a computer psu and so far its going good, except for one thing. I recently scrounged a 12v air compressor from a buggered car battery jump starter, and it runs fine, but whenever i connect it to the 12v and ground cables on the psu the psu just shuts itself off, does anyone know why? or what i can do to stop it from doing it?

Question by jockkitto16   |  last reply

24v power supply out of computer psus?

So i watched a video a while ago, it was about turning a psu into a lab bench psu. The guy said you can run 2 of them together making 24v, having to cut the (earth)ground on one of them and have them running to the same outlet. So i can have the 24v but what about 3.3v and the 5v? im not really sure how those would work, wouldnt they just stay at their normal voltage levels?

Question by knexsuperbuilderfreak   |  last reply

Capasitive start and run.?

I have build this circuit and works great for a 12v pc fan on the bench for PWM. When i hooked this into my ATX power supply to regulate the fan speed the fan doesn't like to run unless i touch some portion of the pcb i build the circuit on. I spliced the wires from the ATX power supply into the PWM circuit, then out of the PWM circuit back to the fan. I guess its a  capactive issue. What could be the fix for this? The other An EE suggested i add several diodes inline to slow the fan down....hhmm maybe

Question by WWC   |  last reply

How to preset current regulation & short circuit protection ?

Found this awesome diyr Linear power supply design with voltage & current controlling- Foe more details-- 1>Since it has no short circuit protection apart from the fuse,then how to preset current just like bench power supply by shorting the the leads ? 2>Without short circuit protection will the  2 two 2N3055 blow up ? 3>Please assist that what should be done for the modification.

Question by Dimitrioptimus   |  last reply

How to drill holes in thin steel? Answered

To save me going through the trial and error stage (I can only eat so many Altoids), what is the best way to drill a matrix of neat 5mm holes in the lid of an Altoids tin? Centres will be 12.5mm (1/2") so reasonable gap between. How do you clamp and support the tin without bending it? What drill speed do you use? Centre-punch first? Drill pilot holes? Drill from the inside or outside? I have a bench drill and usual workshop stuff available.

Question by AndyGadget   |  last reply

ATX power supply conversion

I know this is a long passed DIY. But while building a ATX Power supply I separated all the wires as stated. I then put the green and a black wire to a switch and added the 3 brown leads to the orange leads. When I plug in the unit the supply light comes on, but when I turn the green wire switch the main power LED goes out and no fan comes on. It acts like the switch is shutting the unit off.  Can anyone help. I am 60 years old and just getting into doing some bench work to pass the time. Thanks for any help.

Topic by Shorty954   |  last reply

Broken PSU? Answered

 I recently seen an instructable on converting an old computer PSU into a lab power supply. I followed it correctly, connecting the orange wire to the brown, the green to black and a 10W Wirebound resistor across red and black. The PSU turns on and all of the voltage rails work (although some are out by +-.75V sometimes), but I can hear a faint screeching noise and the fan doesn't spin.  I though the screeching may be normal because all I normally hear is the fan, is this okay. The fan is rated at 12V 0.3A, but when I measured the voltage over it, it was only 3.4V, why is this and how do I fix it. Any help appreciated, Thanks. 

Question by R055_28   |  last reply

Laptop Fan Help!

So i bought a 2.8ghz laptop from a guy for $30i fixed EVERYTHING, invested about $200 of my hard-earned moneyand now the CPU fan wants to crap out on me >: ( the fan works, the circuitry that controls the fan has failed (on the mobo)so what i am asking is that you help me!i need to be able to regulate the 12v that comes from the battery into lower voltage, with a variable power supply, need someone to do the calculation so that i can regulate voltage form 4.5v - 12v what would be the resistance values?VOUT = 1.25 * ( 1 + ( R2/R1 ) )

Topic by Sandisk1duo   |  last reply

Can I make these projects to sell?

I want to offer an instructable building service (through the instructables forum) for people who want a project but can't build it. I am going to have a list of projects that I am comfortable building and will build for people. These are the instructables I am going to start with: Can someone tell me which of these I can use. Also how to tell on any instructable whether or not I can use it. Also if anybody has any other sugestion for this endeavour I would apreciate it. Thanks

Question by nurdee1   |  last reply

Possible to use a single foot pedal switch to activate a linear actuator?

I acquired this mechanism which I would like to modify for ease of use. The original set up uses a linear actuator and a 3 way toggle switch. The linear actuator comes with built in limit switches. The 3-way toggle is not practical as my hands are fully utilised on the work bench. I would like to modify the set-up so that I can use a single foot pedal switch to get this motion. One step on the foot switch and the linear actuator extends to its maximum length. Then another step on the same foot switch and the linear actuator retracts to its maximum. Any help with the circuitry and parts will be greatly appreciated. Thanks in advance. ROY

Question by anslemroy   |  last reply

can i power a warm water geyser with 8.10 v?

am brand new to electric and electronics, i know very little. the motor (gemini gate motor) tested on a bench with a drill produces 8.10 volt. so what i need to do now is step up the volts to 13 or 14v so i can charge batteries, then build a small inverter to step it all up so i can power a geyser for warm water. in my naive state i tried to measure the amparage through the motor and s i connected it into the circuit it produced 3.5 amps so what i think i have is a 8.10v motor (peak rpm) with 3.5 amps which i have to make power a warm water geyser.

Question by nicobotha12345   |  last reply

Can I charge a 6v SLA battery with a small voltage-regulation circuit based on the LM350 and a 12v SLA?

I know that Lead Acids are pretty tough cookies in the battery world as far as over-voltage and charging goes, but since I lack an electronic engineering education, I would like to make sure I don't blow H2SO4 everywhere.  I would be monitoring the charging to see when the current drops to the low mA's, and would not have the battery on a constant trickle charge for very long.  I just need the cheapest way possible to charge the battery  >.<  any other recommendations would be appreciated! I had been borrowing a bench supply, but had to return it and now have nothing.  *forever alone*

Question by mojofilta   |  last reply

Is a Wooden Enclosure for Electronics a Good Idea? Answered

I am in the process of converting my ATX power supply into a bench power supply. My PSU's standard case is made from 1mm steel with various ventilation holes, there is also a 120*120mm fan.  However, the circuit board is strangely positioned within the case and there isn't enough space for what I want to add.   I would like to take all of the electronics and rehouse them in a home-made wooden case. My question is; Is this a sensible thing to do? I plan to use 5mm pine stripwood to remake the box, but slightly bigger and better arranged. I would still fit the fan and drill plenty of ventilation holes.  Do I need to take any extra precautions if using wood, or is it just a really bad idea. Thanks in advance. 

Question by R055_28   |  last reply

Which Boost/buck converter? LTC3780 vs LM2577S LM2596S

Hi, brought two boost buck converters to build a bench power supply from a atx psu.  Brought the LM version first as i have read previously that these are quite efficient, then seen the LTC one, so thought i might as well buy that as well.  Looks like the LTC board will be able to go down to lower voltages and appears to have a greater efficiency, quoted up too 98%, compared with the LM's at around 80%. Thou i understand that with adjustments changes efficncey.  LM2577S LM2596S;=STRK%3AMEBIDX%3AIT LTC3780;=STRK%3AMEBIDX%3AIT Which one do you think i should use? Regards

Topic by JonathanM221   |  last reply

Are high power resistors really neccessary on a benchtop PSU conversion?

Was looking through the site and I was just wondering--why all the huge resistors on the bench-top power supply conversions of PC Power supplies? From personal experience this seems like a waste of perfectly good electricity.I know that they require some current to just stay on however in designing a project for my school's Engineering Technology department I found that the heat generated by such a small resistance (Around 10 ohms) was unacceptably high. Originally I was looking at Instructables and this sitethis site for inspiration but all the cooling measures taken to prevent the high power resistor from becoming a hazard seemed rather silly. A few calculations and experiments later with the 250 watt power supply and I determined that 160 ohm1 watt resistors and 1K 1/2 watt resistors were perfectly acceptable for the purpose of keeping the PSU awake and functioning. I connected one of each between each voltage and ground. According to calculations I can get away with dissipating a grand total of two watts or less spread across multiple resistors.The current divider rule dictates that if you add resistances in parallel, the resulting resistance will be smaller meaning more current will flow through the overall circuit. However this increased current will divide itself across the parallel resistances according to the rule Ix= RtIT/(Rx+Rt). The current through and power dissipated by the resistor you've soldered into the PSU will not change enough to be significant no matter how large or small a resistance you attach in parallel with it--with the exception of an effective short and what in God's name are you doing intentionally shorting the terminals of your bench-top PSU? Now several months later, the PSU is still operating happily and powering multiple micro-controller projects on a display board. Therefore I can reliably conclude that the high-power 10 ohm resistors in many computer power supply conversions are probably a gratuitous waste of wattage. You can get away with using a higher resistance and a resistor that dissipates much less current.

Topic by Psickattus   |  last reply

URGENT need help building a power supply for a 12v winch motor max rating 30A URGENT

Im trying to build a power supply for a parts tumbler ive been working on (instructible coming soon!) ive been using a battery charger to run it right now but it doesnt have enough power, i would need something that can output 12v about 30A max ( thats the value of the fuse the motor uses) im trying to mod a computer power supply right now but i dont think that this will be enough either, i want to build something from the ground up designed for this purpose that would cost max 30 bucks or is there anything else i could adapt? ive searched everywhere but only power supplies i can find plans for or any advice are either bench top ones for electronic projects (5v), any help would be greatly appreciated and thanks in advance to anyone that can help me out

Question by bart.p   |  last reply

I need help using a salvaged laser diode.

I recently took apart a broken original xbox, can you believe people just throw these things away? anyways i got a few nifty parts, including the power supply which i'm tempted to turn into my bench's power supply, a hard drive which quickly became the first hard drive i have ever taken apart, and a laser diode salvaged from the cd drive. I'm going to go out on a limb and say it's a bit more sturdy than say a processor chip so would i kill it if i started probing the contacts with a 3 volt power supply? also there are three contacts, set in like a triangle type deal, the only thing connecting it was a small film that connected it to a nearby board, i snipped the small tape so the leads are separated. how can i identify what leads do what and how can i find the right voltage to get this diode kicking? also as a bonus question, could i just plug the power supply in and use it straight like that or would i need to short a lead?

Question by waldosan 

36Vd.c. @ 8.3A Power Supply + Buck Converter

Hello Friends, I have a 36Vd.c. @ 8.3A Power Supply that I would like to convert into a Variable Bench Power Supply. After researching the topic, I have decided on choosing a Buck Converter as opposed to a Linear Regulator.  Shopping around online, I stumbled upon the LM2596 Converter:;=item462bb7a8a5                      Any thoughts and or suggestions? Beyond that, I do have a general question... I've read on a few power supply instructables that it's recommended that all rails be used (for example all yellow/12v cables) to insure a more steady current. Now being that the max output of the above mentioned power supply is 8.3A and (please correct me if I'm wrong) according to the supplied spec sheets, power is coming from 3 rails, would it be safe to assume it not necessary to feed all rails into a buck converter since its output is only 2A? Please put me in my place...

Topic by davidkiyan   |  last reply

need a little guidance with an arduino controlled CNC machine. help?

Ok so I am in the process of getting the axes set up, and theyre in a state that would allow me to test them. I am using the laser carriages from CD-ROM drives, so i know i wont get amazing build sizes, but that isnt the matter here. I've searched and searched and searched and have yet to really find definite instructions. The hardest part is going to be coding the arduino. I would like to use an ATmega16, but a 328 will work too. I intend on using L293D's to control my motors. they seem to work fine for on the bench testing, so with cooling in an enclosure i dont see why it wouldnt work. but I have no idea where to start with the coding. Ive seen references to GRBL, some reprap stuff, and a LOT of people being told basically "your method is stupid, buy these motor controllers and use my method", which i guess works well, but I dont have the money to buy the fancy motor controllers and the 293s seem to work fine. so, can someone point me in the right direction, or give me some pointers here please? I'd really appreciate it.

Question by zack247   |  last reply

ADC Vss/Vdd on PICs(AVR/ARM is ok too) for external measurements?

Hello, i'm trying to read analog voltages from an external source such as bench supplys and sensors. I can read voltages from withing the PIC's board, 5v, 3.3v...  But if i try using an external power supply i can't read. If i just probe the (+) wire, i can't read...if i plug the (-) wire in the gnd/vss of the board/pic, there's a voltage drop on the supply's voltage, and i can read it, but it sounds wrong. I also already tried to use the vref+/vref- pins, and didn't make any difference, i think. Like, 3v from the supply drops to 0,4v  on a multimeter and in the pic adc value. It looks like it's right, but that voltage drop isn't "ok". I read something about single-ended and differential, but i couldn't find any real explanation. So, the bottomline i need to use external voltage sources, and i will read 4-20mA sensors so, they will use external power, i can't use the boards sources and gnd/vss. Can someone shed some light on the matter?

Question by pmlemes   |  last reply

How do I calculate an LED power supply? Answered

 Okay, I don't know a lot about LED's but here's what I've done so far. I bought some 12v LED strips and used them to surround a display in my shop. I soldered all the strips together and attached my bench supply.  The LED's seem pretty forgiving and I can run them at a reasonable brightness at anything between 8.3 and 12 volts. 8.3 volts draws 0.065 amps and 12 volts draws 0.65 volts. I have no idea why it seems to draw less current at a lower voltage, unless my ammeter is faulty on my PSU. I am now wanting to attach a power adapter. I have a 12v 500mA supply but am worried it won't cope. I also have a 12v 1.25 amp supply but am guessing this may up the voltage and burn out the LED's. Do I really need to buy a 12v LED driver or can I get away with a cheap non-switching adapter?  And if so do I need to go for something like a 12V 650mA? Thanks Simon

Question by slysimon   |  last reply

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

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

Question by sheasmith   |  last reply

Having trouble measuring voltage with arduino.

I have posted this question before but I’ve made a few changes with my circuit with no luck. I’m trying to make a variable lab bench power supply with an lcd screen to read voltage and current while adjusting them. I’m using TL431 to have a 2.5v Vref and  a op amp in voltage follower configuration with 10M and 1M trimmer (Divider) on the input to finely calibrate 38v down to 2.5. The op amp is acting like a buffer. This is the code I've come up with: float volt; int sum = 0;                   unsigned char sample_count = 0; #define NUM_SAMPLES 10 void setup() {   analogReference(EXTERNAL);   Serial.begin(9600); } void loop() {   while (sample_count < NUM_SAMPLES) {    sum += analogRead(A0);    sample_count++;    delay(10);     }    volt = ((float)sum / (float)NUM_SAMPLES * 2.5) / 1023.0;     Serial.println(volt * 15.2 ,3);     sample_count = 0;     sum = 0; } Parts list: LM358 (for now, will upgrade to a unity gain stable op amp) 10M 5% resistor 1M trimmer Arduino Mega (Will use a pro mini in the final circuit) Breadboard (Will this effect my readings?) TL431 (2.5v Vref) Yes I now the LM358 is not suited for this application but I don’t think this will affect my readings by much, about 5% maybe. Will it? This code is gives me OK values at start but when I start to decrease/Increase the voltage. It lags behind and offsets by 1-2 volts on the reading. My goal with this project is to read (LIVE, meaning while changing voltage with buttons and see it change without any offset/lag) Voltage with a resolution of +-5/10mv accuracy and also read current (But thats for a later day). One last thing, I’m 16 so a lot of electronic terms tend to go over my head so please while giving an answer keep it simple if possible. Thanks :D

Question by faraz ahmed khan   |  last reply

Having a peculiar issue with the max6675 and grounds?

So first off, this is an application for use in a car. I have ensured that all of my grounds are good, and the power is clean, so I know these are not the issue, at least not on the car side of things. I am trying to get an electric fan controlled by an atmega328 (through a relay), which I have successfully achieved  on bench tests using an alternative heat source. It works reliably until I apply the circuit in the car. When I install it in the car with my thermocouple on the radiator pipe for the temperature reference I get all sorts of temperatures that are not the correct one. Its either very high, or very low. I have tried multiple thermocouples (of similar style) with no changes. If my thermocouple is not making contact with any grounded portion of the car (for example, the engine) it reads fine, so I know that my issue lies somewhere in there. An easy solution would be to simply mount the sensor in a coupler in the radiator hose (thus isolating it as best as I can) but I would rather fix the issue than apply a bandaid. I've tried searching for other people having a similar issue but haven't had any luck. One peculiar thing to note is that if I have the ground disconnected, and the thermocouple touching a ground, the system receives power, so I am assuming that the junction makes contact with the outer case of the thermocouple. My circuit is nothing too elaborate (I can upload a schematic if need be); I have a DC/DC adjustable converter to get 5v for the micro and 6675 power, which does not have an isolated ground, an atmega328, an OLED display, some tact buttons, and a max6675 development board. There are other passives as well but those should be minor. Does anyone have any idea what may be going on with this? I'm stumped. I should be able to provide any info you may need.  PS: this is the development board and thermocouple that I am using: 

Question by zack247   |  last reply