[sdiy] Where to buy ceramic caps

Tom Wiltshire tom at electricdruid.net
Sat Dec 30 16:56:57 CET 2017


Maybe a combination of the two methods?

Your original list of cap values covered a wide range (150pF to 1uF, 4 decades), which is a bit of a stretch. Similarly, resistors from a few hundred ohms to several megohms is a bit of a stretch.

If you used a few standard cap values (Say 1n, 3n3, 10n, 33n and 100n) you’d be able to find all the caps from the same range, and you’d be able to keep the resistor values within a tighter range and not push the performance of other stuff in the circuit (like running op-amps with very low or very high input impedances, for example).

HTH,
Tom

==================
       Electric Druid
Synth & Stompbox DIY
==================

> On 30 Dec 2017, at 09:38, David G Dixon <dixon at mail.ubc.ca> wrote:
> 
> So, after much cogitation, I'm thinking that I may just do this the other
> way round.  Instead of trying to keep my resistances within a certain range
> (around 30k) with all different capacitor values, I could use the same
> capacitor value for all 12 stages.
> 
> If I used 10nF, then the resistances would range from about 374 ohms to
> about 3.01M.  These values fall within the range where I could use one or
> two standard 1% resistors to achieve the value within about 0.01% of the
> target.  The advantage is that 10nF falls within the range of C0G caps,
> which are standard 5% tolerance (and often significantly better).  Plus,
> there is the added convenience of only having to deal with one value of
> capacitor.  I could buy a pile of these (I can get them for 12 cents apiece
> at my local shop) and sort them into groups.  This is a value that my DVM
> reads quite accurately, so that's easy enough to do.
> 
> The beauty of this is that I can actually build it in different ways and try
> them out.
> 
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