[AMRadio] Cap Substitution


Geoff/W5OMR ars.w5omr at gmail.com
Thu Feb 14 22:10:25 EST 2008


JT Croteau wrote:
> I have a circuit that rectifiers power from a 24VAC tranny tap using a
> 1N91 to power a 24VDC relay.  It calls for a 50 uF filter cap to
> ground.  Can I substitute a 47 uF?
>   

Sure.  if you're unsure, use two 47uf caps in parallel... or a pair of 
33uf's...

I'm reminded when I asked an instructor about 'why bother to do exact 
calculations for resistance and/or capacitance if the manufacturers 
don't make, for example, a 54.5kOhm resistor, or a 51uf capacitor?"

He said "Ah, Geoff!  Welcome to the wonderful world of Electronics!  The 
Exacting Science of Approximation!"

Gotta say... he's got a point!

--
73 = Best Regards
-Geoff/W5OMR



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