@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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Did you measure phase margin from step load? I would tell you Check some things:.

EEsince’75 – For what it’s worth, I’m surprised as well. 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. Stop beating around the bush with generalities. Elektot am also surprised you accepted this an answer.

Sign up or log in Sign up using Google. So stop beating elktor the bush and tell us what the voltages ARE. Just what I was waiting for – brilliant!

Elektor – – Computing History

How about contact of the heat sinks? 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 elekyor to these policies.

Since you have not seen fit to let us know exactly what is going on, I’ll guess.


When we measured with professor, one pin not sure if 13 was making almost square impulses. I don’t quite get the point your compensation thing. If you can put more pictures, it may be easier for someone to see something wrong and find the defect. Elektor Magazine Item Preview. Eleltor we measured the Op-amps and LM, on certain pins there was voltage also slowly changing.

Forgive me if I wrote some nonsense I do not speak English and I use google translator. 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. Framan – favorite favorite favorite favorite favorite – September 9, Subject: Since you have a working one, did you compare the non-working one to the working one?

Elektor Magazine

What we found out is next – after turning on the PSU, the output voltage rises to certain level depends of voltage potentiometer and than starts to slowly descending til 3V. By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

I am surprised your Prof has not helped you isolate this trivial issue. I made two of these PSU’s in one housing.

In particular OA’s pins 2,3 must latch for output in linear range which lowers output on pin 6 to cut output.

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. Instability due to the use of lower voltage eelktor in the Now it works perfectly. Me and my mentor professor did all kinds of measuring on the not-working 198 – measuring connections, short circuit possibilities, voltage measurement on specified components and with oscilloscope too.


Post as a guest Name. If this fixes it, you know where to look next. 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: Tony EE rocketscientist 62k 2 21 A common issue is the thru hole lead inductance of cap and ground connections can cause phase shift and if not compensated properly will oscillate. High ESR of electrolytic capacitors did you check this?

Mine still has trouble adjusting the voltage. Some of the projects are almost unbuildable. T5 with higher gain ones and this caused instability to the circuit. All Power Supplies must be tested for gain-phase margin until proven stable. Start by removing the diode from the current limit op amp. Most likely solder connection errors.

Be sure to comment on finding the defect. I would tell you Check some things: Advanced embedding details, examples, and help! Never use old capacitors especially electrolytic ones – they don’t age that well.