[R-390] Re: Tantulum Capacitors

[Dave Maples]

All: I just looked up the datasheet on the LM317K and it calls for a 10 uf
cap paralleled by a 1 uf tantalum on the output, and a 0.1 uf cap on the
input.  I don't see any call for a 50 uf tantalum anywhere.

Of course, I'd feed this thing from a full-wave bridge with several thousand
uf for a filter, as is done in a typical PS.

Why not do this?  Look on craigslist or freecycle for an old PS for a CB
rig.  Probably 12 VDC at an amp or two.  Turn it down to 9 VDC.  Of course,
you don't get the satisfaction of building your own 9 VDC PS, but so what?

Dave WB4FUR

-----Original Message-----
From: r-390-bounces at mailman.qth.net
[mailto:r-390-bounces at mailman.qth.net]On Behalf Of glwebb at gundluth.org
Sent: Wednesday, September 24, 2008 8:35 AM
To: r-390 at mailman.qth.net
Subject: [R-390] Re: Tantulum Capacitors


     My somewhat faulty memory says that  the big advantage of tantulums is
that they have lower leakage
compared to a similar value common electrolytic capacitor.   I used to see
a lot of them in medical
equipment.   In the circuit you described, maybe a low-leakage electrolytic
would do the job fine.
I would try that, or if you want to use tantulum, parrallel 10's 15's or
22uf's.

Gary Webb, NI9V

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