Precision power supply (#92, December 1982)

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Postby luganez » Sat May 19, 2012 12:00 am

Hallo to everybody.


I know this is a question about a circuit "something" old, but is a design that I liked and I could not do, even though I bought the PCB by the EPS service, and I could not end at the time

This is the "precision power supply" which appeared in the magazine number 92 December 1982 in the English edition. On the cover reading "the power supply: 0 to 30 volts, 3 amps" and showed two high-capacity electrolytic capacitors and a toroidal transformer, on a green background.

Now, after a few years, I'm back, and I've mounted it again, but I have two doubts:

The first doubt is regarding the ammeter. The schematic indicates that it has to be of 100 microamperes, but the one I have has a full scale of 5 amps. Obviously it does not work, even moving the needle. I wonder how it could be installed in the circuit to use the calibration by P3. I know I could put in series with the load, but then I lose the calibration by P3, plus I do not know if I should put a resistor in parallel with the ammeter.

The second question is related to the total power delivered by the power source. Having three 2N3055, how is it possible that the power supply delivers only 3 amps, one for each transistor? According to the article, it is because each transistor can not dissipate more than 50W, and to obtain the maximum output voltage (35V) is recommended the use of one transistor for one ampere, to avoid exceeding those 50W.I understand that if I have a maximum voltage of 21V, I could get two amps for each transistor. Is that correct?. In addition I have cooled the transistors with a good heatsink and a fan to avoid overheating.


What do you think about this?

Thanks and regards.
luganez
 
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Postby christiansen » Tue Oct 09, 2012 12:00 am

Hello, i am sorry if i disturb you..a am seek for these magazine ( elektor December 1982) very long time,i need few pages copy from this magazine, Precision power supplay,so plase can you help me?? if you be able sent to me this pages obout this power suplay,scheme,elements list,etd...etd... i be thankfull !!

Best regards
christiansen
 
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Postby thijsbeckers » Wed Oct 10, 2012 12:00 am

We have a gentleman's agreement on backissues dating before the e-era. Contact our service department (service (at) elektor (dot) com) att. Cindy and use kind language .
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Postby kesindestek » Mon Nov 19, 2012 12:00 am

I can not find the diagram ELEKTOR published in the journal in December 1982- Precision laboratory power supply 0-30 v. 3 A for a copy of the schema and pcb Can you help?
Project no: 82178 Thank you. thanks
kesindestek
 
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Postby Elektor Editor » Tue Nov 20, 2012 12:00 am

Kesin, read carefully.

1. send an email to: service at elektor dot com.
2. address it to: Cindy.
3. Use: kind language otherwise you'll get nothing
4. state exactly what you want, Cindy is not technical.

Jan
Elektor Editor
 
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Postby kesindestek » Thu Nov 22, 2012 12:00 am

Thank you, jan
Cindy (service@elektor.com) I sent an e-mail. Waiting for response.

[admin edit] content removed. Elektor forums are not designated to publish individual correspondence.
kesindestek
 
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Postby kesindestek » Fri Nov 23, 2012 12:00 am

[admin edit] content removed. Elektor forums are not designated to publish individual correspondence.
kesindestek
 
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Postby kesindestek » Mon Nov 26, 2012 12:00 am

[admin edit] content removed. Elektor forums are not designated to publish individual correspondence.
kesindestek
 
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Postby toprak sergen » Mon Jan 21, 2013 12:00 am

No, you don’t put a resistor in parallel with the ammeter. Use the only to get shunt which is not the case here. I didn’t understand the second question in your initial post. Please clarify that.

quick turn pcb assembly'
toprak sergen
 
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