Recent content by st2

  1. S

    0-30 V PSU negative supply not working

    Yes I realized that 😀 Well, I've got a populated board and I'd like to try getting it to work to avoid contributing to electronic waste 😁. The board is small and limits modding and upgrade opportunities. I'll try rigging up 4 AA batteries for -6V negative supply and see what happens. I tried...
  2. S

    0-30 V PSU negative supply not working

    I had some time to analyse the simulation, it appears there's a problem of current, the negative rail needs 40 mA but the charge pump can provide no more than 9-10 mA before collapsing (with my 23.4 VAC to start from). On my board I discovered that U3 is too hot to touch, perhaps it's shorted...
  3. S

    0-30 V PSU negative supply not working

    Thanks for your kind reply! I tried simulating that too (Simetrix), sorry for bad image without captions, top is D5 anode voltage, then D6 anode, then D7 anode, bottom: current in mA in negative rail. No zener regulation here too...
  4. S

    0-30 V PSU negative supply not working

    Hi folks. I built this PSU in its original version, with 081 opamps and 5.1V zeners. I understand the circuit is rather old and has been improved over time, but I already had the PCB and the whole thing is getting me to learn something, so I'm trying a troubleshoot before tossing it into the...
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