15 uF non-polarized?

[KazooMan]

While I am awaiting a shipment from Mouser of parts for my U-Boat Sub-Octave, I have been putting together a copy of R. G.'s "Neutron Filter".  I actually had almost everything for the build, except I decided to order the H11F3 Phot6o-Fet optoisolators rather than rig up one of the options.  Those arrived in my latest shipment from Smallbear, but I am currently dead in the water looking for a 15 uF non-polarized capacitor for the input.  I missed that on looking over the parts list to see what I have.   I don't have anything close to this.  I will be heading out to the local "electronics supply" tomorrow to see what I can find. Any tips on what I really need?

[italianguy63]

I have 3 extra here if you can't find any...  MC

[mth5044]

deleted

[PRR]

The circuit is odd. While I suppose we need to know the "legacy" values, others will work.

If you are sitting there with your thumb in your ear, waiting for a 15NP to appear before you can even try it..........

First -- jumper where the cap is. 99% of the time this will be fine. The cap blocks DC leakage from whatever is driving the effect. Most sources don't leak much DC.

Second: use any cap you got, 1uFd or larger, polar if that's what you got. The goal is to get full bass (but no DC) into a 3.3k resistor. By simple hi-fi rule-o-thumb, we need 3uFd. Guitar can get away with 1/2 or 1/3 of this, so 1 or 1.5uFd. Guitar rarely plays its lowest note, so for -testing- you could even go 0.5uFd, admitting that if you like it and want the full bass depth, you will order a 2+uFd when convenient. Polarized cap will work for months or years, unless it comes up against *severe* DC leakage the wrong way.

BTW: two 16uFd back-to-back (connect the "-" legs together and use the "+" legs as "non-polar legs) will be 15uFd NP for all practical purpose. Buying NP caps saves a can and two legs, but is the same idea internally.

[merlinb]

You have many options:
Use a different value. Can you get 10uF? or 22uF or 47uyF? It's not critical.
Use an ordinary 47uF polar cap. Provided the power rails don't spend a long time starting up astymmetrically, this is OK.
Use two ordinary 33uF (or similar) caps back-to-back.

[KazooMan]

Thanks for all of the advice, especially the back to back 16uF trick.  I think I have those in my parts bin.

I had looked all through my stuff trying to come up with some combination that would get me close to the 15uF without much luck.  I didn't realize I could stray so far from the value and still get good results.  I'll see what I have that will work to have a test.

[duck_arse]

if it were my maths, two 33uF caps *in series* ~equals 16u, non-polar.

[italianguy63]

I have 3 extra here if you can't find any...  MC

I can probably get 100 of them if anybody wants them.