[sebhc] IC information

[Dwight K. Elvey]

>From: "Barry Watzman" <Watzman at neo.rr.com>
>>
>Chips will sometimes take a lot more abuse than you expect
>
---snip---


Hi
 A 7905 will take a short to ground for some time
but it will only last a short while with a voltage
on the output that is greater than the input. Although,
one should use a lot of filter capacitors on the rails,
excessively large capacitors on the rail can cause
failures when the power is turned off. One should
put a diode from the input to the output that is
reverse biased during normal operation.
 The negative regulators are also more sensitive to
over voltage on the inputs. If you have a number of
transformers on the same switched line, it is a good
idea to add a MOV across the power to soak up any
inductive spikes. I've seen this wipe out several
power supplies when the fellow turned a number of units
on and off with a power strip, instead of the individual
power switches. It isn't a problem today with the
switchers.
Dwight


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