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From: Chuck Simmons
Organization: You jest.
X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.0.33 i586)
Subject: Re: Op-amp configuration question
Date: Wed, 02 Oct 2002 00:59:38 GMT
NNTP-Posting-Date: Tue, 01 Oct 2002 17:59:38 PDT
> I've got a schematic with an op-amp configuration I have never seen
> before. It's purpose is to take a 6.2V reference and amplify it to a
> 10V reference used elsewhere. It's set up like a non-inverting
> amplifier with the 6.2V to the + input, and a 10k R1 and a 16.5k R2
> for the divider at the - input. This much I understand. Where it
> confuses me is that there is a 332 ohm resistor pulling the output up
> to 15V, and a 383 ohm resistor from the output to the + input. What
> are these added components used for? The amp is a LT1014 and the 10V
> is used for pressure transducer excitation. Thanks for your help.
The 383 ohm resistor would make sense if the 6.2 volt reference is a
zener diode. The regulated +10 volts with the 383 ohm resistor would
give a nice constant current for the zener. If I am right so far, the
332 ohm resistor is a "start up" resistor. Since the reference has no
current source at start up, the extra resistor insures current in the
zener if the offsets in the opamp do not cause it to head for the
positive rail initially.
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons firstname.lastname@example.org
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