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1 in 3 VCO C14 Capacitor Question
MUFF WIGGLER Forum Index -> Oakley Sound Systems  
Author 1 in 3 VCO C14 Capacitor Question
Flareless
I'm building another (awesome) Oakley VCO and have another PCB set on the way. On the first one I built, which works great, I used a 1nF 100V 1% 100V Polypropylene cap (Digikey part # 399-7694-ND).

In the spreadsheet of Mouser part #s available on Tony's site it lists Mouser part # 23PS210 which is a Polystyrene axial capacitor but the sheet lists the tolerance at 1% and Mouser lists it at 5%.

I'm out of the Digikey parts but I do have 5% Polystyrene 1nF 100V caps in stock.

My question is would it be preferable to order and use the 1% Polypropylene cap (which works great in my other VCO) or can I use the 5% tolerance part which I have several of?

I just want to make sure that when it comes down to adjusting the tracking I have the best possible capability for fine tuning. My first one with the 1% part actually tracks more accurately than my Q106 across a wide range of octaves.
Synthbuilder
I've given 1% as that is the tolerance of the capacitor type I used. It also means that if other makes are used you are pretty much guaranteed to get a good capacitor - and by good I mean one that doesn't vary its capacitance much with voltage, age or temperature.

In practice any polystyrene capacitor can be used. 1% or 5% just state the tolerance of the value of the capacitor. The VCO itself is not bothered whether the cap is 1.2nF or 800pF so long as it doesn't vary with time and temperature. But the great thing about polystyrene is its good temperature stability and longevity. And you get that whether you buy 1% or 5% polystyrenes.

So use 5% polystyrene with no worries.

You can also use the now commonplace C0G ceramic capacitors that weren't around in values like 1nF when I designed the VCO.

Tony
Flareless
Great information as always! I'm going with the polystyrene.

Thanks for clearing that up Tony thumbs up
mmeixner
Synthbuilder wrote:

You can also use the now commonplace C0G ceramic capacitors that weren't around in values like 1nF when I designed the VCO.

Tony


Does that mean that C0G capacitors are an equal or even better choice in applications like this?
Synthbuilder
mmeixner wrote:
Does that mean that C0G capacitors are an equal or even better choice in applications like this?


I'm hesitant to say yes in all situations but for VCOs and filters they do appear to be an excellent choice. They still aren't available in large values though so for anything bigger than 10nF you are still probably better off with polystyrene or polypropylene.

Tony
mmeixner
Synthbuilder wrote:
mmeixner wrote:
Does that mean that C0G capacitors are an equal or even better choice in applications like this?


I'm hesitant to say yes in all situations but for VCOs and filters they do appear to be an excellent choice. They still aren't available in large values though so for anything bigger than 10nF you are still probably better off with polystyrene or polypropylene.

Tony


Thanks for clarification! The many choices with capacitors are not easy to grasp for beginners.
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