Jump to content
Electronics-Lab.com Community

PicMaster

Members
  • Posts

    90
  • Joined

  • Last visited

    Never

Everything posted by PicMaster

  1. Yes I know I was going to do that any way, I've decided to layout a PCB for it, Even though I know that the design is not complete or may not work, The reason I've gone down this route is this way as long as the schematic is correct the PCB will be correct and less chance of any man made errors in hooking it up, if all goes well then we are half way there and can make minor/major changes if needed. once I spent hours trying to find out why a circuit i did on bread board did not work and it was a man made fault(I got some wires wired wrong), the PCB is almost completed, I shall use the press n peel method to make real quick and easy.
  2. I will make a start this afternoon on it, It will be built up on my bread board rig, Hopefully it will work has good has it does in the simulator, I will take some pics of the tests, I have no problems where you post them, I have a load tester where I can make the current variable from 0-10amps but we will only be set to 3-5amps the 10A version can come later as well as the digital control part So I can carry out a good load testing at different volatges to see how really well the PSU performs for long periods of time, Of course I shall use fans to keep things cooler ;D I will report on progress
  3. I have now obtained most of the parts for it so I'm ready to start building it, I've got the correct chip now ;D. has anybody built it yet means this topic was disapearing off the list
  4. I say I never saw it or if you did answer I may have asked before but it's been a few weeks and been to bed since then many times. I would only use the LM324 has a stand in for the trial; I thought it just be nice to see how it would perform in real life The next time I place an order I shall order the correct chip.
  5. By all means feel free. The purpouse of this is below 15V we only use the one side of the transfomer and above we use the 30V side of the transformer, This prevents generating to much heat at low voltages Yes R5 is the current resitor, Many electronics suppliers should sell them I know Farnell & RS do sell them and there world wide. You can use what ever MCU you like, The more designs make it more interesting and suits everybody's neeeds. I personally use PIC'S. The volatage out of the TL431 is just abouve 5volts this is the referance voltage for the voltage boost on the op-amps. So a referance voltage for voltage measurements I would use another TL431 on the digital board anyway
  6. Herro Could I use a different type of op-amp say a LM324 or some lm741's, I know that the higher input voltage would be no good, But has I have not got around to order the correct one yet, I was thinking using the above op-amps but only use a 15-18V transformer for the trial I know this will not be the 30V version but say a 20V version. Only I've got a bit of spare time to start playing with and get this topic moving again My thinking it should prove it to a certain degree at at least we can see if the voltage/current adjustments work and see how good the ripple, Correct me if I'm wrong.
  7. Just to let you all know due to other commitments I will not be able to fully help in building and testing the power supply, :( :(. I have to get this other project finished that I've been working on has they have brought the completion date forward :(. I will keep an eye on this topic and any spare minutes I will start and progress in getting it built up on breadboard I mean whiteboard ;D(only joking). I have got most of the parts ready just need to get to order the op-amp and mosfets which I shall do on the next order I make. I was so looking forward to playing around with it.
  8. Ok May be not max volts/amps setting so it cannot bed excceded but a amp setting reading so the use can see what the max curret is set rahter than geussing because if you set it to high and your PCB under testes have faults then bang ;D I've add a quick look at the parts list/schematics, I shall print them off to have a good look over, What about a LED for current limit indication, well thinking about it that will come later has we need to know that this will work first ;) Could we not use a smaller heatsink with one or two fans on them, I use a heatsink 200mmX100mmX40mm with with 4 x .47R 100W resistors in parrell carrying 30amps constant between 4-6hrs with 2 60mm fans and the temp did not even get above 50 C, If the fans fail then the system shuts down.
  9. Oh no I see that we have lost 3 pages of the topic What's going wrong ? I no this is jumping the gun a little but I've been playing around with the Digital part well laying out the GLCD for volts and amps, I shall try the bigger fonts and aslo the standard font, If we use the standard font there is a lot more room to play around with. What do we need to display apart from the voltafe/current readings, We could have a max set volts/current . Herro how is the final sechematic and parts list looking ?
  10. The MCU with LCD 6/8 push buttons and may be 2 digital pots I would say no more than 100-200MA may be well lower, I would say if you allowed a max of 500ma this should more than enough, I will look into it for a more accurate figure, but the 5V supply would need to be filtered well. I will try altering the Load resistor and run some more graphs just to compare I like the idea of adding a boost transistor so that it can be rum from a 5V source, Now that I've got the latest drawing I will compare it agaisnt mine aswell
  11. What about 2 x 6800UF 50V caps These are new_design_psu.pdf
  12. I did do that in the end I reduced the 39V zener to 36V and used a 4.7V zener and with no load the pot now can go to 0% and still obtain the voltage out, If used 33V zener with 4.7V you don't obatin the full voltage out, I placed the current porbe on the output it reads 0.001A with the pot set to zero. So far everything seems to be working great in the SIM,
  13. I have added the -9 supply and to me makes it worse, well in sim mode I now have to take the current pot to 8% before I get a voltage instead of 2%, Unless some thing else needs altering.
  14. I've start to look at part and The supplier I use I can't get the 22000uF caps but can get these 10000UF 50V 105C HE SERIES SNAP IN RC Rapid part number 11-3165 from here http://www.rapidonline.com/Electronic-Components/Capacitors/Radial-Electrolytic/Low-profile-snap-in-105-deg-C-2000hr.-electrolytic-capacitor/80204 I find these are cheaper than RS on most of there stuff but the draw back is not has much components at RS, If the crunch comes to the crunch I will order the correct ones, Rs always seem to have a SSM quanity but rapid most of there stuff is one off's
  15. Sorry this was after the new year party, I will explain better now Herro the +88.8 is greyed out when the simulator is not running(this is there default state), Once I start the simulator they then read the correct voltage. I've re-looked at the drawing and made the correct modifaction to my drawing added C5,R23&R24, C5 is 1N and R23 is 100k, I changed the value of R24 to 680R. Yesterday when I tested it the sim did not run so I put it down to adding the above parts but I went through I sim log and found a couple of errors with s 100N cap I used and reinstated the above part and it ran fine, I placed a current porpe on the output with the pot set to zero the prope reads 1.70693e-05 coming output side of U2 is 0.096MV at 2% the probe reads 0.008A the output voltage U2 is .098MV and at 3% the probe reads 0.1398A and the voltage is 0.14875MV. So I'd say if your having problems I'd put it down to LTspice. I hope this explains it a bit better for you Steve
  16. Yeah this is for testing purpose only, It was the only way that I could get to simulate it because with the mosfet in there i was only getting max voltage out and no variation in the output. I know that simulators can sometimes play up causing all sorts of problems let's just hope this does not happen real life. Yes may be but we would have to complete the bom and source the components and the data sheets to get the correct sizes so the footprints can get made. Why digital pots, You could just use a op-amp as a buffer/protection and read the the voltage/current,the temp and control a fan all at the same time, But if you like the idea of digital pots then may be we could have 2 interface add on's ;D Yes I know it's sounds trivial but needs to be thought of, Has for the LED's to state constant current or constant voltage is not so important but we need to add all the stuff soon before we come wup with a working prototpye. Next year ;D (week) I shall get the op-amp and a few other bits ordered ready to start biulding that's providing we stick with the chosen op-amp, Well this has been very interesting and would love to continue working on this project but the wife telling me to get ready to go out, Happy new year to you both and We'll speak next year ;D ;D Alex what language do you write your code in ?
  17. I'm simulating mine in ISIS and everything seems to work OK, To get it to Sim correct I've had to remove M1 and replace with relay has I could not alter the output voltage has the way it is drawn it always stayed at max output voltage, The way it is set up at the moment to me is working great according to the Sim, The voltage goes from 0-30.2(this is because I got veref set to 5V), I then close the switch on a 0.1R resistor and then alter the current from 0-5.01 amps the voltage drops right off to 0.16V, I have also tried bigger value resistors and gone through the range and the voltage/current remain stable, I've tried to add the 2 100k resistors as per your latest drawing and it will not Sim so I know that by adding these 2 resistors that cause's the problem, I removed them and everything back to working, Now this where I get confused and how much faith do you put in these Sim programs, Normally they are spot on if it does not work in ISIS then it does not work in the real world. Some times I get problems in simulating but in the real world everything OK ??? My drawing attached, I've not really used LTspice at all, it is all new to me so i'm just playing and learning how do you alter the pots in LTspice new_design_psu.pdf
  18. The velleman power supply I have got had 2 pots that you had to calibrate min and max, the had to be set for about 2-6ma and the max was for 5amps, I suppose that's how they got around it so when the main current limit pot turned turned to zero the calibration pot prevented the volts from droping to zero I never thought about that bit, It maks sense now ;D I had a play around with the values of the TL43B to make vref 5.01 and the max current went to 5.01 where has before it only went to 5.63 has that what the vref voltage was, Would it possible just to alter the gain slighty so we can control it with 0-5V (4.95V), may be this where the min and max pots could be used just incase you overshoot 5amps and at the same time this will cure the volts problem with the current pot turned to 0
  19. I would say limit it to 30V has the extra 3 volts woudl not make that much difference I totaly agree has it's simple and an easy to obtain the part, Cost does play a apart in slightly but it want want to build a quality PSU then cost does not matter to much, After all if you had
  20. Sorry on reding it back I should of not asked that question really I did not mean to sound to be rushing.
  21. It was only a thought has they used that in a Velleman 0-30V 0-10A psu which I did have one and never seen the voltage drop has it will be has quick has the mosfet, But if the mosfet is the better way to go then that's the way to go how long do you reckon before we can build one for real and start playing
  22. I know I would of used 10bit PWM myself, Just has a thought instead of using a mosfet to switch the higher volatge what about a relay instead Like the drawing below, Once the output reaches 12V the relay kicks in the higher voltage
  23. Looking and studying the drawing more I can now see that M1 acts as a switch silly me. I understand now you are correct in saying that I've got resistors that used to dissipate the heat. I will see if I can find any more info out, I did build the circuit on a test board so that I could control it with another pic but I found that under load some parts blew up can't quite remember which parts did hsa I give up with it and never looked any further into it, I may have had it wired up it wired up wrong I'm pritty sure that this was one of the web pages that did it but they do a newer design now, may be worth a look http://www.linuxfocus.org/English/June2005/article379.shtml I've attached a zip file containing the other version of the elektor PSU, This is what is said about it you guys will understand that more than me, PIC_Power_Supply.zip
  24. Has I understamd this was not a very good power supply, I've never built it but others copied it and they removed there design off there web sties saying it was unstable, but you may be to understand it better than me I love this topic I'm learning so much from you guys it's mind blowing, Thanks Looking at the Schematic I see you have used 3 mosfets for the output current but only one to switch the main current, can you please explain the logic behind it Woulld we get away with only using 1 mosfet ?, I have a 30/50amp discharger which only uses 4 mosfets and they don't even get warm. but then again I may be talking nonsence has it works the other way ???
  25. I can help out there, I have the code working to a degree, I send out a smooth stable volatge of 0-5V with a coarse and fine settings, This can be sorted out once we have a working power supply, we can just include it on the PCB this way people can a have a choice what they like to build. Yes they can be interfaced with MCU but can only handle the same voltage has MCU which is 5V, I've also code some code some where to adjust them. I've never has the need for 50V supply and not sure that many others would either, The PSU I'm running at the moment has never been above 13.8V really well once it went to 28.8V this was just to set up a battery charger timer card, If you think about it you could just build 2 and you can get 60V, Has for the display we can either use a LCD/GLCD or 2 x 4 7 segment displays or even both the leds will read actual voltage/current the LCD could display the max voltage/current settings and Temp, These are just ideas and can be added later if needed
×
  • Create New...