Recent content by woody3

  1. woody3

    L200 Reg plus LM741 Op Amp PSU

    Hi Audioguru Been putting this through its paces. When I use the pot to reduce voltage under load (250 mA) from max, it cuts to 14 volts and 130 mA very soon after turning the pot. When I turn the pot fully up it stays at 14 v. The only way I can get it back up is to switch the whole thing off...
  2. woody3

    L200 Reg plus LM741 Op Amp PSU

    Hi Audioguru I replaced the L200. It is bolted and electrically insulated on a large heatsink. R3 is a 0.1 Ohm 10 Watt resistor. The main filter cap is 6800 uF and is doing its job. Still no joy. L200 pin readings are : (1) 33v (2) 1.23 - 1.38v (3) 0v (4) 0 - 1.23v (5) 0.9v...
  3. woody3

    L200 Reg plus LM741 Op Amp PSU

    Ho Audioguru I swapped the 741 for a TL071. I get 30.6 Volts out regardless of volts pot setting. When I put a load on the output (66 Ohm) the volts drop to 0.9 and current is 13 mA. (At least it looks like Ohms Law is working!) Any idea what's wrong please Woody
  4. woody3

    L200 Reg plus LM741 Op Amp PSU

    Audioguru Many thanks - I will try the Op Amps you suggest and let you know the result Woody
  5. woody3

    L200 Reg plus LM741 Op Amp PSU

    Hi y'all Can someone help please: Made a current limiting PSU from circuit in the L200 spec sheet as below. Can't get the current limiter to work and am thinking I'm frying the OpAmp. :'( It gets 30 volts but its own spec sheet says 22 volts max. Is there a solution or am I barking up the wrong...
  6. woody3

    Power Supply Meter Problem

    Hi Audioguru Thanks for the response. Problem is I bought them from a seller on eBay located in California who seems to have got them from a Chinese? source. - and I'm in the UK! >:( That having been said they seem good quality. You are right there is RF flying around as I get a fluctuating...
  7. woody3

    Power Supply Meter Problem

    Hi MP Thanks for the reply. The meters need a 5v supply to function. The other psu is purely serving as a source of an imput to be measured. What about putting a link between the -ve 5v supply and the -ve input? as per attached? Sorry to be a pain but I need these working for my new 0-30v psu...
  8. woody3

    Power Supply Meter Problem

    Sorry - trying again woody
  9. woody3

    Power Supply Meter Problem

    Hi MP/Audioguru Not exactly a scematic but hope it serves the purpose Woody
  10. woody3

    Power Supply Meter Problem

    Hi Audioguru I'm measuring voltage of a separate (different) PSU output at its panel terminals and current being drawn from the same source to run the fan - just to give me a measurable load. Meters are powered by the little PSU at 5v. So I'm not trying to get the meters to measure their own...
  11. woody3

    Power Supply Meter Problem

    Hi Audioguru Thank you for the reply. The LED meters each draw approx 41mA (measured) when lit (3 1/2 digit) and functioning. I'm using a 4,700uF cap for smoothing. Fan is drawing 110mA making a total of 190mA. Total is well within tx spec. Any advice on the 'mutual interference' of the two...
  12. woody3

    Power Supply Meter Problem

    Hello - this thread has gone very quiet - everybody soldering?? Some help ,please: While waiting for my main PSU pcb to arrive I've been putting together an auxillary psu for my two LED voltage and current meters and a 12v supply for a fan I want to put in the PSU box. I've used two 7805s off...
  13. woody3

    0-30 Vdc Stabilized Power Supply

    Audioguru Many thanks for the advice Woody
  14. woody3

    0-30 Vdc Stabilized Power Supply

    Hello I'm an 'old' newbie recently retired. Am returning to my electronics hobby after 30 years! I made a 1A current adjustable psu many years ago but it got the boot in the many moves around the world. I've followed this thread for some time and was close to buying a kit of parts for the...
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