[R-390] Re: Slighty OT: Question about tantalum caps (Barry)

[Ed & Mary Wambold]

Barry,

47 mf @ 50v is 47 mf @ 50v, it does matter what type of cap you use, unless 
you are concerned about physical size. Tantalums are more compact and other 
than that, they are equivalent to regular electrolytics...

Ed, N3LHB

> Message: 2
> Date: Tue, 23 Sep 2008 20:36:38 -0500
> From: "Barry" <n4buq at knology.net>
> Subject: [R-390] Slighty OT: Question about tantalum caps
> To: "R390" <r-390 at mailman.qth.net>
> Message-ID: <000601c91de5$fdbe4030$6401a8c0 at ingrnet.com>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=response
>
> I think I mentioned on this list that I'm in the process of thinking about
> considering the possibility of maybe one day building a 9VDC power supply
> for one of my radios.  Yes, it's solid state and begins with a "G" (and 
> ends
> with "rundig") so if you want to stop reading here, I understand.
>
> I was getting the parts list together and the circuit calls for a few
> miscellaneous caps, one being a 47uF 50V Solid Tantalum cap.  Perusing the
> Mouser catalog, I find this capacitor is quite expensive (in excess of $20
> each).
>
> Can anyone explain to me the advantage of using a solid tantalum over some
> other "plain-jane" capacitor?  The circuit uses an LM317K and this
> particular capacitor is connected across the output just before the 
> ammeter
> and voltmeter.  (The circuit is in the 1978 ARRL Handbook (page 127)).
>
> I was fortunate to have meters that will make the project nice and figured
> that would be lion's share of the cost, but this little cap (along with a
> couple of other items) have really driven the cost of building this thing
> nearly out of sight.
>
> Can someone/anyone tell me if another type of cap would work as well?  Are
> the caps of today better than those of 30 years ago, so much so that maybe
> the solid tantalum wouldn't be necessary?
>
> Thanks!
>
> Barry - N4BUQ
>
>
>