Testing PS filter caps

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#21
Conrad Hoffman said:

Nice potentiometer- Guildline is excellent (and expensive) stuff. Without looking in detail, it looks like it's basically a 6-digit voltmeter. The voltage reference would have been a Weston standard cell (mercury/cadmium) at 1.018 or so volts. If you haven't already, go research "Kelvin Varley Dividers" as a first step to understanding the thing ;-)
Click to expand...


Guildline made the voltage divider for the HP 3456A DVM -- still one of my favorite instruments.

Another good source of high precision potentiometers for measurement work are the Keithleys -- sometimes you will see them paired up with a Keithley 240 HV power supply. The Fluke voltage references...

Jim Williams (Linear Technologies) did an application note on Kelvin Varley Dividers -- it's in a piece on a 20-bit reference which they devised. Williams stuff is always a pleasure to read.
 
#22
I haven't started to build it yet. Doing some web research, I realized that my local surplus store has 4 of these (below). They are on the top shelf out of reach, but I recognized the GIANT meters, and made the connection.

GenRad_1654pic.jpg


GenRad_1654pic2.jpg


Of course I realize Conrad's version is smaller (a lot), but I do suppose I could buy one of these big beasts, the above Gen Rad 1654.
I'm guessing they'd let one go for $60 - $100.

Any thoughts on the difference between the two? What would you do ?

btw, the manual has some good reading...
http://bama.edebris.com/download/gr/1654/GR 1654 Impedance Comparitor.pdf

=RR=
 
#23
Conrad Hoffman said:
The topic of testing power supply filter caps seems popular, and many people don't have a capacitance meter or bridge.

[cut]

An externally hosted image should be here but it was not working when we last tested it.


[cut]
Schematic
Click to expand...

I resume this quite old Conrad's post because it seems that the links to the picture and schematic are broken.
As I'm interested in this topic I kindly ask Conrad if he can restore the correct link

Thanks in advance
Regards
diy_audio_fo
 
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