[sdiy] Hand selecting capacitors

David G Dixon dixon at mail.ubc.ca
Sun Apr 11 00:43:25 CEST 2021


Yes, that's what I'm doing.  I'm not trying to get all 1.000nF, 10.00nF,
100.0nF, and 1.000uF caps.  If I have enough 972s, say, then I'll use four
972pF, four 9.72nF, four 97.2nF, and six 972nF caps.  If my Dome filter is
designed for a range of 0.1 to 10000 Hz, then this will change it to 0.1029
to 10290 Hz, which is totally fine.
 
The problem is that most of my caps for the first three values lie between
mantissas of 960 and 1030, but nearly all of my 1uF caps are between 1030
and 1050.  However, I've just resigned myself to having to customize one
resistor associated with each 105 cap.  As it is, today, I have enough caps
to stuff six 18-stage Dome filters without customizing, which is nice,
because that's exactly how many boards I've made for stuffing.  I need to
order various values of 1% resistors for the other builds (I currently have
20 orders for this frequency shifter, all to be built by hand, by me, in my
garage -- be careful what you wish for, I believe the old saying goes...).

  _____  

From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of
Bernard Arthur Hutchins, Jr via Synth-diy
Sent: Saturday, April 10, 2021 10:30 AM
To: synth-diy at synth-diy.org
Subject: [sdiy] Hand selecting capacitors


[CAUTION: Non-UBC Email]	

 

The performance issue here is a VERY wide-banded min-error response (not
something like a sharp bandpass).  If ALL the caps in a lot are, say, 4%
high, the response is just shifted down by 4% but is essentially unaffected
in the broad middle range that is likely all we really need.  I don't see a
real problem. 

-Bernie
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