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building a diode voltage clamp

Posted: March 31st, 2016, 9:07 am
by TOKABU
Hello all,

Long story short we had our Keithley 6485 - (peeco ammeter*) repaired by Keithley and to prevent a future issue they suggested to build a diode voltage clamp to protect the meter.

The email recommends using a 2n3595 or MMBD1503 diodes as they are low leakage diodes. I haven't had such luck finding them (2N3595 doesn't exist) or they are SMD only.

I've found an old pdf from keithley out on the web building one:

https://doc.xdevs.com/doc/Keithley/Over ... tion22.pdf

and they recommended using 1n3595 diodes which are plentiful and cheap. Mouser doesn't say if they are low leakage or not. (see below)
http://www.mouser.com/ProductDetail/Fai ... y1m2LNsIzc

The 2 links below DO say they are low leakage, would they work for this application?
http://www.mouser.com/ProductDetail/Fai ... S3uKPjA%3d

http://www.mouser.com/ProductDetail/NXP ... porary-tag

Any help is appreciated!

Thanks

**PS forum is censoring the word "Papa India Charlie Oscar" ammeter.....

Re: building a diode voltage clamp

Posted: March 31st, 2016, 10:24 am
by Dale C
The diodes should be 1N3595. Not 2N3595.
These are low leakage fast reacting diode.
They should do the trick.

Re: building a diode voltage clamp

Posted: March 31st, 2016, 10:55 am
by TOKABU
Perfect, thanks!