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Smitjuh's Achievements


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  1. Ha thats my thought... I already did a few tests with a meter acros R7 and it works wel, it needs some math to get it right but I will make it work!
  2. YES!!!! ;D ;D ;D ;D ;D ;D ;D The thing works perfectly by now!!! It indeed was a short betwwen pin 6 and 7 a nasty one, but all short are nasty one's! ;D ;D I can't thank you enough audioguru!! I will place pictures when it is in it's housing! one thing... what is the best place to add my amp, and voltage panel meters? greetz Tim
  3. :( I already tried the swapping option.... The op-amp isn't the problem. Can't there be a problem with one of the transistors? I will check them for bad working of wrong placement later this day.
  4. Output of U3 is 33,5 V. Values of R20 and R19 are like described in the project, 10k and 2,2k. So not wrongly painted, or got a alightly different color due to heat or something. I checked the PCB several times on shorts, but I can't find any. The 24V can be al bit more, I read it quickly on a analoge needle voltmeter... But when the load is on, and the current pot is turned counterclockwise, I can see my voltage build up when I turn the voltage pot. until about 30V and then the voltage drops (realy quick) to say 25, 26V Thanks again for the fast and good supply!!! Greetz Tim
  5. Audioguru, I changed the op-amps to TLE2141CP one's. The supply regulates ok. At a full load, it won't exeed 24V. But with all the losts in the supply this seems ok. But my LED still won't light... U3 get's realy hot... maybe that rings a bell? Greetz
  6. NO it isn't. Like audioguru mentioned in one of it's earlier posts, you can change R7 to other value's. If you give it a higher value, the max. current will drop. ;)
  7. Shooter, You can use 2x 0.22 Ohm 5W resistors in serie! Then you got a 0.44 ohm 10W resistor... It's just a thought...
  8. Hi audioguru, Here I am again ;) I changed my op-amps to 44V rated ones (op37 from Analog) But With the last op-amps I could regulate from 0-32V, but now It is only possible to about 24V. And when the supply is powered for some time, the voltage decreases slowly. down to 22V.. When currents are flowing, it all go's wrong and my voltage drops dramatically. My LED still don't lights at any time...
  9. Hello! Audioguru! In your last post to me, Changing U2 and U3 was a option.. well, option it was nescesarry because they where working outside their workingvoltage. Well I changed them with LM741's. But there is no difference in the working of my powersupply. If I turn my Potentiometer P2 wholy clockwise, and I put a ballast on my output, my powersupply gives, lets say: 10V 1,5A. If I turn back P2 (counter-clockwise) noting happens. Until the last part of the turnig cylcle... then the voltage fals down with about a 0,5V.. current remains the same.
  10. Positive supply: 34.4V Negative supply: -5.65V Drop at 3A: about 1V (34.4 to 33.5) Voltage on the outputconnectors also drops a little when turning P2 down. So I can control the current, but only for a very small part....
  11. with a 10k resistor on the base of Q3 the LED lights! I've tested my opamp (U3) little comparator test, and this one still works. (AD711 Analog Devices) But my Supply voltage goes down... the voltage connected to the collector of the 2N3055...
  12. Hi!! I replaced some components with the better components mentioned by audioguru. The BZX zener and the both TIP31A's also some resistors. But my LED won't light!! The output from U3 (pin6) is 34V when pin2 is in voltage value above pin3 Pin6 remains 34V. but when I turn back P2, pin2 of U3 gets below pin3 and the ouput, pin6, is decreasing til say, 26V. Is this in theory enough to light the LED?
  13. Hi audioguru, I changed R4 to a 1K value, and my Voltage value has climed from 10.7 tp 11.2V!! I did not used the BZX zener, but this one will be delivered soon I hope. I looked at you're schmatic and see that the voltage acros R7 becomes 1,4V when there is a current flow of 3A. I tried it and what happens.... When I measure the voltage accros R7 when there is a current of 3Amp, the voltage is -1.4V!!!!!!! How can it become negative???
  14. Hi audioguru, reading this forum, you're the man for all my questions ... I think ;) As entioned before in this topic, my current control circuit won't work properly. I will give some measurement results. On Pin 3 I can control the voltage from 0 to 1,7V (no load) witch is correct, because R18 forms together with P2 andR17 a resistor devider. At max, the next equation gives us: (10k/(56k+10K+33))*10,7=1,62V When I put a load on the circuit (Resistor) I can control pin # from -0,2 to 1,5V... Thats is already strange for me... The Base of Q3 has to become more negative than his emitter voltage so the trasistor can switch on, what lights the LED. To get the Base voltage far below 34V, pin 6 of U3 must get Low. This is only possible when Pin 2 of U3 becomes higher then pin3 of the op-amp. And here is the mystery.. pin 2 only gets lower when a current is flowing trough the shunt resistor R7! ??? What am I missing?? I hope someone can help me!! thnx in advance!
  15. Pin 2 of U3 becoms more negative when I turn up the output voltage... I can't realy find why..
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