>>which is why one puts c. 100k-ohm resistors in series with the input
>>pins.
>
>Not if you want the best temperature stability. Because input offset and
>bias currents vary with temperature, using 100kohm series resistors
>makes it worse:the variation in input offset currents give bigger offset
>voltages. A smaller resistor (1k?) should be enough to kill the oscillation
>without running into that problem.
>
? osc. pales in comparison to the rfi problem. To pass the 2m handheld
test, it takes a fair amount of R at the input pins. A current gain of
over 500k is nothing to sneeze at. .
>But I don't like 723s anyway.
? According to my Fluke, the 723's excellent performance in the pos.
floating screen reg. is not a fluke. The temp. stability appears to be
excellent.
>An interesting question: How long are they
>going to be around? They are an old design, on an old process. The trend is
>towards 3 terminal regulators of higher performance; I wouldn't design a 723
>into anything on the basis of its age now, and the replacement situation in
>few years.
? so buy ten and toss 'em in the bin.
>
- later, Peter
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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