I realize that better references are available.
I was thinking of resurrecting a long-defunct Fluke 731 that I have in the
garage. The reference IC is bad in it, and (1) I don't want to throw it
away without a meager attempt at repair, and (2) I don't want to spend a lot
of money on it because it's in pretty bad physical condition.
I was hoping that someone could lend a touch of advice on those old
references. I have a few 1N827A reference zeners, and a washtubful of
transistors. Maybe something could be cobbled together that would get the
731 back in operation. Maybe not to original specs, but close, which is
better than nothing.
Thanks for your reply,
Dave M
Jack Mcmullen via volt-nuts wrote:
Just thinking why would you reinvent a transistor/zener reference
when the industry's voltage reference chips are in the $2.00 or less
single quanities with performance far exceeding anything previously
available in discrete components??
-----Original Message-----
From: Dave M <dgmin...@mediacombb.net>
To: FEBO Volt-Nuts <volt-nuts@febo.com>
Sent: Sat, Sep 12, 2015 1:58 pm
Subject: [volt-nuts] Making a Reference IC
I was looking at the schematics for the Fluke 731 and 732 voltage
references. these, and several other brands and models of voltage
references, use the same or similar reference ICs as their basis. The
reference ICs are a Zener/NPN transistor pair on a single substrate.
Please view in a fixed-width font such
as Courier.
|
|
C |
|
|
|
|----
| B
/|
/ |
E |
|
+---------------
|
/------/
/
------
|
|
Just thinking... would it be possible to make a reference with similar
characteristics with discrete components (a low tempco Zener and a
transistor)? They would likely have to be closely coupled thermally
and
maintained at a constant temperature within an oven or by a peltier
device.
What criteria would apply to the selection of the parts?
Dave M
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