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Everything posted by zedd

  1. Obviously I should have read some docs about operational amps before I asked you :) My simulation was OK, i just understood it wrong. You are right about the voltage drops on the transistors. If I set the gain like you designed then the U2 output is 30V when R11+pot is exactly 34250 ohms. And the voltage drop between U2 output and "+" is 3,13V so the "+" is 26,87V. When set R11+pot = 28840ohm, the U2 output is 33,35V and the "+" output is 30V. The conclusion is to use a smaller pot, like 5k, but I'm not sure that I should trust simulation results - will check that after assembling the device. Thank you for your help.
  2. Hello Audioguru It's amazing that this topic is active for so long long time, and you are still here :) You are doing great job here, helping people and improving the original device. Thank you! I read both huge topics about this power supply, noted all changes and comments, to create single project file (i'm using Altium Designer) including simulation files, schematic, pcb layouts for smt and tht. I'm going to share that project on this forum as it is not easy to find all informations here (the topics are too big, and there is no single message with updated informations). The schematic, sim libs, schematic libs and pcb libs for smt are done. Working on PCB layout now. To provide most confident data, I will upload it here after assembly of the device (waiting for some parts now) so it will be checked and working after assembly. I think it will be finished until end of the month. I will provide both smt and tht versions of PCB. Please confirm: - the newest bill of material is rev.3 from page 55 - the newest schemativ is rev.2 from page 55 - the highest voltage of the transformer is about 30V for TLE2141 or MC34071 (as in last posts here) but better is to use slightly lower voltage transformer, to avoide the risk of exceeding oamp's maximum supply voltage. I also have some problem, but I'm not sure if it is a simulation issue or not. The U2 gain should be about 3x to provide 30V output (11.20 from U2 * 3 - some voltage drop on transistors). But simulation shows that the gain is smaller (about 2.5) if R12 is 56k and R11 is 27k. I changed values of those resistors to reduce negative feedback and obtain exactly 3x gain on TLE2141. This caused the *simulated* circuit to work better with high load, no ripples at all. What do you think about it? Was is tested by you (the gain on TLE2141)?
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