[volt-nuts] Power Designs Precision Power Supplies

Marvin E. Gozum marvin.gozum at jefferson.edu
Wed Apr 25 13:55:41 UTC 2012

This is fantastic news, glad to meet you here.  You knew them at 
their prime, when they were like new! While CC is standard in many of 
today's supplies, its hard to find modern ones at this cost that 
match the PD Precision regulation.

The stability is impressive even today, and moreso, the Precision 
series have their key regulation components all transistors.

Since you mention repair, were some less durable than others?  I can 
see calibrating per your protocol as needed.

I looked up the transistors in the 2020B and 5020 and half of them 
are unobtanium.  By chance, does anyone have the specs of 
these?  I've tried the web based resources and located 2 transistor 
specs, and were barely readable.


Does anyone know what these voltage references where?

Voltage References

At 03:40 PM 4/23/2012, Dave M wrote:

>I used to repair and calibrate lots of Power Designs supplies back 
>in the late 60s and early 70s.  They were always top-notch supplies, 
>very low noise & ripple, and seldom failed.
>For instance, the ripple/noise spec for the model 5015 was < 250uV 
>RMS. amd stability was 0.01% +5mV per 8 hours.
>The model 2020 precision supply ripple/noise was 100uV P-P, and 
>stability was 0.001% + 100uV per 8 hours.  Very nice supplies.
>I have several of the PDI supplies in my shop, and use them 
>often.  They are excellent supplies.  I love the constant current 
>mode on them; that feature has saved more than one project from 
>going up in flames.
>I have a model C500 (0-100V/0.5V precision supply) that needs 
>repair.  The reference assy is bad; haven't had time to get into it.
>If you need manuals, I have PDF copies of a few models, (mainly 
>models that I have in my shop).  Post your interests and if I have 
>the manual, I'll send it to you.
>Dave M
>A woman has the last word in any argument. Anything a man says after 
>that is the beginning of a new argument.
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Marv Gozum
Philadelphia, PA  

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