@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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Just what I was waiting for – brilliant! Isolate the problem section, determine the error, and fix it.

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T5 with higher gain ones and this caused instability to the circuit. TR2 is power stage of 26V. Thank you Thank you so much, it was a fantastic job. Then the elekfor changes slowly from 3V-5V. 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. Be sure to comment on finding the defect.

And are you sure the – supply is properly isolated? I made two of these PSU’s elwktor one housing. Most likely solder connection errors.

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: How, exactly, are the two supplies connected?

192 we measured the Op-amps and LM, on certain pins there was voltage also slowly changing. Instability due to the use of lower voltage 192 in the Topics ElektorMagazineCollection.


If the first PCB works without this compensation then why would the not-working one need it.

I am surprised your Prof has not helped you isolate this trivial issue. Forgive me if I wrote some nonsense I do not speak English and I use google translator. Email Required, but never shown. How about contact of the heat sinks? If this fixes it, you know where to look next. Elektor Magazine Eleltor Preview. Not all of the information is current. Elekhor still has trouble adjusting the voltage.

Grounding has a big influence if oscillating at say 10MHz did you scope pin 13 yet?

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Possible batch elrktor fake LM? If you can put more pictures, it may be easier for someone to see something wrong and find the defect.

Did you measure phase margin from step load? I don’t quite get the point your compensation thing. Me and my mentor professor did all kinds of measuring on the not-working PSU – measuring connections, short circuit possibilities, voltage measurement on specified components and with oscilloscope too. I found your data useful but not in the presented form, so I imported into a spreadsheet to align the results in two columns and then imported the images from the datasheet PDF.

Stop beating around the bush with generalities. Sign up using Email and Password.

Listen to what IgnacioVazquez-Abrams elekror too. Now I can access them again on-line – how good is that? Thanks for the effort it took to get this all together.


I don’t really bother what went wrong there. Home Questions Tags Users Unanswered. I hope someone has any ideas or has worked on similar project so I can solve my problem which stayed unsolved till now.

But second one causes a problem on the output that couldn’t been solved yet. And if I connect load on the output the voltage slowly descends till 0V everything seems like there should be a capacitor making these problems. I am grateful if you can help as I used google to translate this message before. Glad your circuit works.

Never use old capacitors especially electrolytic ones – they don’t age that well. I myself don’t have the scope. I collected Elektor for nearly 20 years but sadly I had to give them away due to space limitations. Since one PCB worked perfectly and the other one didn’t, I made another one with new board and all elements new.

Tony EE rocketscientist 62k 2 21 All Power Supplies must be tested for gain-phase margin until proven stable. Sign up using Facebook.

I am from Brazil, I am also mounting this source 3 outputs: My LM regulator works well with stable 7. Now it works perfectly. I would tell you Check some things: