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| TL431 linear power supply |
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| mike_mike:
--- Quote from: spec on December 14, 2018, 09:20:55 pm ---mike_mike Current limiting added to PSU circuit version 3 of reply #45, as per attached schematic: --- End quote --- C2, C17 and C15 are 10uF non polarised capacitors ? Does they really need to have such a big value and they really need to be non polarised ? R11, R16, R6, R13 could have a more usual value ? |
| not1xor1:
--- Quote from: spec on December 14, 2018, 09:20:55 pm ---mike_mike Current limiting added to PSU circuit version 3 of reply #45, as per attached schematic: --- End quote --- some notes: - The common emitter stage inverts the phase so you have to swap inverting and non-inverting inputs. - I've not made any calculations yet, but I think it would be safer to replace some transistors with BD139/40. - Probably it would be hard to compensate. I'll see if I can simulate it. |
| xavier60:
--- Quote from: not1xor1 on December 15, 2018, 09:28:39 am --- - The common emitter stage inverts the phase so you have to swap inverting and non-inverting inputs. - - Probably it would be hard to compensate. --- End quote --- When the op-amp's inputs are reversed, its minimum gain becomes unity. This can be a problem if there is too much gain elsewhere in the loop. I know from recent experience. |
| not1xor1:
--- Quote from: xavier60 on December 15, 2018, 09:51:06 am --- --- Quote from: not1xor1 on December 15, 2018, 09:28:39 am --- - The common emitter stage inverts the phase so you have to swap inverting and non-inverting inputs. - - Probably it would be hard to compensate. --- End quote --- When the op-amp's inputs are reversed, its minimum gain becomes unity. This can be a problem if there is too much gain elsewhere in the loop. I know from recent experience. --- End quote --- What do you mean? In the classical floating PSU design, where the opamp inputs are swapped, the overall gain can be set to 0. |
| xavier60:
--- Quote from: not1xor1 on December 15, 2018, 10:19:21 am --- In the classical floating PSU design, where the opamp inputs are swapped, the overall gain can be set to 0. --- End quote --- With the floating type regulator I built recently, the reference ended up on the CV op-amp's inverting input and the voltage feedback divider on the non-inverting input. Even if a large capacitor is connected between its output and inverting input, the AC gain can never go below unity. This isn't a problem in this situation because there is no extra gain between the CV op-amps output and the MOSFET's Gate. |
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