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Everything posted by jhanus

  1. Audioguru, thank you for information, I will implement your suggestions.
  2. Thanks, OK, correct me if I'm wrong, with trimpots I will reduce max voltage to 30V and current to 3A, to existing trimpots I will add another pot in series connected exactly like trimpot for fine tuning and that should be it. :)
  3. Thank you, I understand first and the second recommendation and I will implement calibration trimpots. But just for my knowledge, how to connect two pots in series if one has all three terminals connected. If each terminal comes to each terminal that is parallel, but how to realize connecting in series(in this circuit)? ???
  4. Hello, There was a suggestion to put two pots in serial for better control precision, but they are connected with all 3 terminals, as divider. To connect the second pot to adjustment terminal of first?!
  5. Thanks for response, Let say that I will be satisfied even if I get 1.5A at 10V (40VDC-30VDC). Can you put equation for calculating current-boosting transistors or schematic?!
  6. Hi, I found at my local shop voltage regulator TL783 (http://www.ortodoxism.ro/datasheets/texasinstruments/tl783.pdf), it can regulate from 0-125V, I can't use any other regulator because my input voltage is 40VDC. Problem is that this regulator from characteristics can only deliver around 700mA output at input-to-output voltage differentials of 25 V, but I need 3A. So can somebody help me to add current boost like it's done here (http://ourworld.compuserve.com/homepages/Bill_Bowden/page12.htm#317pass.gif), under title "LM317T Voltage Regulator with Pass Transistor". In datasheet there is circuit for current boost, but I would prefer method above. How to calculate this components would be of great help, because there is high probability that I can't buy the same transistors. Thank you.
  7. Thanks for reply. Well what to say,this is bad, I will continue to search for some solution, thanks.
  8. Oh no!, but thanks! This setup all in all will cost me very much, ahh... :'( I know I must be already very boring, sorry for that, but what if I would use redone circuit (http://www.electronics-lab.com/projects/power/003/index.html) for 5A on weaker transformer, let's say 80% of refered power, but wouldn't push it to the end? And if output isn't 30VAC, but 28VAC? Thank you.
  9. Thanks, But now I found that I have a real problem, my second output is 28.28V AC, and that means 28.28*sqrt(2)=39.99V DC, but LM338K only allows 35V cross it, I don't need 35-40V DC, but I need 1.25-35V or 1.25-30V. What to do now?!
  10. Exactly thats the answer I was looking for, so if there is no loss in voltage or current really why not always use 120ohm, if that puts us in secure area. I'm using LM317 and LM337 for (-25)-0-(+25)V DC, could I drop 1.25V to 0 with diodes at output? Can I put on the same coil with already LM337 another LM337 (parallel) to create -1.25V to eliminate 1.25V from positive regulator LM317,and vice-versa?! Thanks again!
  11. Hello, I'm in little dilemma with LM317, I searched trough almost all posts but the final answer wasn't there. **If value is more than 120 ohms then the output voltage will rise, ok if that is correct. So I'm going to put a straight question: if I put 120ohm as R1 where is the difference towards 240ohm (except R2 value, except **), if there is no difference why put any other value?
  12. Again, audioguru thank you. I found OPA445, and with yours recommended list I'm ready to go! And I must say that people like you make this world a better place! ;D
  13. ;D thanks! audioguru ;D I can't buy:- TIP31A, but I can TIP33C, and (BC548,2N2219). - OPA445AP, but I can TL081CN (C=operating temperature 0=>+70, N=DIP8 package). Are they good substitution? Under two paralleled 2N3055, just to connect B-B, E-E, C-C or something else. Thanks a lot.
  14. audioguru, thanks. When you said that they are in this thread, did you mean scattered, or in one place, if they are in one place(plz link) or if anybody is willing to put them in one place?, I can remake the circuit, list all the changes and upload for future viewers. If the answer is no, then I'm off to read,and I'll post as soon as possible my result. greeting
  15. Hello, I'm new here, so I greet everyone! I found this project,and accidentally found this thread, I began reading but there are 85+ pages :o , so plz, can someone tell me is anything wrong with this circuit?! In first few pages there was something about transformer and diodes,and in last some modifications?! ???
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