Polystyren capacitor?

Is it it critical to use polystyrene capacitor for C7, C13, C19, C23 on the 4P Voicecard or can I use any film capacitor?

Assembled my Ambika and the SMR4 VC yesterday. Works like a dream! Today assembled 5 4P VC’s but must have missed the above capacitor in mouser order. Local store only have film caps.

The polystyrene caps are more accurately specced, that’s all. This is only critical in filters in most projects. So, it probably is important. Any film cap measured with a good RCL meter would do if you can select a few with tight tolerance.

If you can wait, I possibly have some spares. I’ll be back around New Year’s. Or ask the you know who’s in Stockholm if it’s urgent :slight_smile:

If you want to use ceramic caps, use C0G/NP0 with low tolerances.

ELFA 65-767-39 (alas 5%, but C0G) 65-862-83 means bending the legs, 65-427-81 are nice films which are 5mm, or roll your own from some multilayer ceramic SMDs. Electrokit won’t bring more options to the table. Bhiab.se has lots of ceramics that will fit, plus some really nice 1% or 2% Styrol (Styroflex) that cost a bit.

…and I thought I was late to bed! :wink:
Thanks a bunch for quick answers!
The film cap above is the only one with +/-2.5%, the ceramics are 5%. Is the film cap the best choice then?
@jojjelito: ofcourse it’s urgent, I have 5 almost ready VC’s for my brand new Ambika :slight_smile:

Filmcaps did the job! Sounds great

You can always measure some and make sure they’re all pretty close.

Awesome! Yup, measure or just subst between C0G, NPO or film.

I picked up 20 pcs of 2.5% film caps and had the intention of measuring but forgot it in the excitement and just built them… :slight_smile:

How can I tell if they are not close enough? Some of them are 1% and some 2.5% and I put 4 of the 1% on the same board but I cant really hear any difference.

I think you’d have to scope it and compare against a Spice model to see any difference. If you can’t hear anything wrong then there’s not much point worrying :slight_smile:

These little variances are what people like about analog.

Matching the values is not necessary. It has the adverse effect of causing self-oscillation to appear earlier over the course of the resonance control.