Re: Sub-nanoampere current measurement and calibration

From: Winfield Hill (Winfield_member_at_newsguy.com)
Date: 09/24/04 

Date: 24 Sep 2004 08:02:12 -0700

Winfield Hill wrote...
>
> prabha_kar@hotmail.com wrote...
>>
>> I want to measure sub-nanoampere (upto about 1pA), DC current.
>> -Can anyone help me selecting the circuit and components to design
>> such an instrument?
>
> Your first task should be to obtain some high-value resistors.
> One good possibility is to purchase an old Keithley electrometer
> on eBay, and scavenge the teflon switches and resistors.

 http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3840791292

 You can tear apart the 610, leave it as is and use it, or
 convert it to a solid-state machine, using one of the NSC
 opamps I mentioned. I have a schematic of Keithley's 610A,
 which has switch wiring and architecture similar to the 610B. 

-- 
 Thanks,
    - Win
 (email: use hill_at_rowland-dotties-org for now)