@Keno – “Yes, heart of the problem is % “the changing of voltage” Right. So stop beating around the bush and tell us what the voltages. Hi, Elektor – I might call- circuit is not bad. Couple of minor modifications made here. Check this out. Item, Type, Manufacturer, Date. Elektor – July/August , Magazine, Elektor – November , Magazine, Unknown. Elektor – October , Magazine.

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When we measured the Op-amps and LM, on certain pins there was voltage also slowly changing. If this fixes it, you know where to look next.

Topics ElektorMagazineCollection. Home Questions Tags Users Unanswered. Any challenge with failures is a good experience to learn.

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Now I can access them again on-line – how good is that? Framan – favorite favorite favorite favorite favorite – September 9, Subject: This old design uses external compensation for 2nd order effects which in closed loop Op Amps causes loss of phase margin and can cause oscillation is no margin. One issue I did retain for posterity was Elektor Book 75 which I could not locate in the English archive listing https: Be sure to comment on finding the defect.

I am grateful if you can help as I used google to translate this message before. Sign up or log in Sign up using Google. High ESR of electrolytic capacitors did you check this?


I would tell you Check some things:. Glad your circuit works. Post Your Answer Discard By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies.

But the information and the descriptions of the circuits and how they function are a very practical way to see the real world of electronics after learning from the textbooks. I am from Brazil, I am also mounting this source 3 outputs: Did you measure phase margin from step load?

I managed to solve it, the defect was because I replaced the original transistors T When I raise the voltage setting the voltage goes up to 32Vdc when it should go up to 47Vdc, when I reduce P1 the voltage goes up and the potentiometer works upside down min: Advanced embedding details, examples, and help! Warning this will affect loop bandwidth and step load response time.

Listen to what IgnacioVazquez-Abrams said too. I changed Op-amp, LM and a few capacitors every of them but smoothing capacitor – my professor said that it wouldn’t be making such problems. Paulo Morgado – favorite favorite favorite favorite favorite – February 27, Subject: Thus something is loading it. I am also surprised you accepted this an answer. If the first PCB works without this compensation then why would the not-working one need it.

Treasure trove of electronics information I first dipped my toes into electronics engineering via Elektor and I have profited greatly from it over the years. Then the voltage changes slowly from 3V-5V. First one works perfectly fine.


When we measured with professor, one pin not sure if 13 was making almost square impulses. EEsince’75 – For what it’s worth, I’m surprised as well. All Power Supplies must be tested for gain-phase margin until proven stable. I hope someone has any ideas or has worked on similar project so I can solve my problem which stayed unsolved till now.

Post as a guest Name. But second one causes a problem on the output that couldn’t been solved yet. My LM regulator works well with stable 7. And are you sure the – supply is properly isolated? Me and my mentor professor did all kinds of measuring on the not-working PSU – measuring connections, short leektor possibilities, voltage measurement on specified components and with oscilloscope too.

182 you Thank you so much, it was a fantastic job.

Now it works perfectly. Come on, this isn’t hard. Mine still has trouble adjusting the voltage. Most likely solder connection errors.

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TR2 is power stage of 26V. Start by removing the diode from the current limit op amp. Search the history of over billion web pages on the Internet.