10 Jun
2007
10 Jun
'07
1:40 a.m.
Van: cctalk-bounces at classiccmp.org namens dwight
elvey
Verzonden: zo 10-06-2007 07:23
Aan: cctalk at classiccmp.org
Onderwerp: RE: LM309K regulator
I would like to hear more about this! I am about to build myself a small
power supply for -16V. using an LM337T. I know that if the output capacitor
is larger than the input filter cap you better put a diode connected between
the output and input pin, and that for HF you should put small caps (say
10 to 100 nF) with short leads from input to Gnd and output to Gnd.
Never heard about that switch-off spike from the transformer.
Since that -16V. is the power supply for my RACAL RA.366 panoramic adapter
I'd hate to see that unit get damaged ... would a VDR across the secundary
of the transformer help?
thanks,
- Henk, PA8PDP
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From: Brent Hilpert <hilpert at cs.ubc.ca>
While conversing with another list member about some old components, I
was reminded of hearing somewhere that there was a nasty failure mode of
the LM309K 5V regulator (it being the (or one of the) first integrated 5V
regs) which might make it somewhat undesirable for current use.
I don't want to declare that there is such a problem - it's a vague
second-hand rumour to me - so can anyone confirm or elaborate on this?
I've never personally run across problems with them..
A 76 Moto databook indicates it has those nice things like short-circuit
protection and thermal-overload protection.. ..another device perhaps?
Hi
Many regulators could not handle significant back voltage. The problem
would often occur if the input had a small capacitor relative to the
output and there was a bleader or other load on the input source.
This was common problem with many CMOS circuits.
Another problem was input over voltage. Often if ther was a transformer
without an input filter capacitor, when the power was turned off, the
inductive spike would wipe out the regulator. It seems like negative
rail regulators were most suseptible to this.
Dwight