Need schematic for current source for 30uAmp

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BABESH

Joined: 27 Sep 2005
Posts: 118
Helped: 10

01 Jul 2009 12:58 Need 30uA current source

Hi
I need schematic for current source for 30uAmp
My load is grounded resistive type sensor as load.

--babesh.

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LordAli

Joined: 22 May 2009
Posts: 40
Helped: 2
Location: Czech

02 Jul 2009 5:24 Re: Need 30uA current source

See schematic of HP3478A. From Hewlet Packard (todays Agilent). There's best drawn schematic of current source with ranges of 100nA to 1mA (not sure for upper range)

Use oamps AD706 and for current source I will fill in today. (I don't remember exactly). Or see schematic Agilent 34401A. Watchout the lownoise, low input current oamp (unipolar input amplifier with low noise like TL051, AD706, ... ) or it will not work properly.

Good luck

BABESH

Joined: 27 Sep 2005
Posts: 118
Helped: 10

02 Jul 2009 7:33 Need 30uA current source

Thanks Ali Bhai,

I got it, i picked up the circuit,
I don't need it much rugged one, first i will try to implement using any opamp

Thanks
Babesh.

LordAli

Joined: 22 May 2009
Posts: 40
Helped: 2
Location: Czech

02 Jul 2009 17:55 Re: Need 30uA current source

Ok, I found my schematic. I used AD706 for bias amps and TL051 for current source. In current source I have transistor 2N6851 or SMD equivalent. Try to have the very high input impedance of current source oamp.