1pf cap?

[coot]

I recently gutted an old tape deck (it was quite therapeutic!), and ran across of number of resistor-type caps. The one in the image seems to be 1.01pf (unless I'm reading it wrong)...
What function does such a low value serve, in general? Secondly, do such small values come in handy in pedal building?

[garcho]

Secondly, do such small values come in handy in pedal building?

Nope.

I can't speak to what it's used for in a tape machine. Was there a radio receiver on this machine? That would be my guess. Might be some type of filtering going on that required a non-standard value, like 11pF, for instance, and it was cheaper to buy a 1pF and a 10pF than an 11pF.

[bluebunny]

The one in the image seems to be 1.01pf (unless I'm reading it wrong)...

1 0 x 10¹ = 100pF ?

[garcho]

^ Sounds more like it. You're certain it's a capacitor and not an inductor? Could be 100µH.

[Mark Hammer]

Craig Anderton used a fabricated cap in one of his early Guitar Player projects.  It consisted of two pieces of insulated wire twisted together.

[Axldeziak]

Craig Anderton used a fabricated cap in one of his early Guitar Player projects.  It consisted of two pieces of insulated wire twisted together.

That's called a gimmick capacitor. Rough estimate is about 1pf per inch.

[cloudscapes]

There's more capacitance in those leads than 1pf.
Caps of such small value are likely to only work as surface mount.

[coot]

The one in the image seems to be 1.01pf (unless I'm reading it wrong)...

1 0 x 10¹ = 100pF ?

Maybe? I based my (not well-informed) assumption on color codes for tropical fish caps; but this isn't a fish...

^ Sounds more like it. You're certain it's a capacitor and not an inductor? Could be 100µH.

I'm not certain of anything... the perfboard labelled them as C###.


More generally, I have absolutely no idea what I'm doing. Just trying to find a hobby to weather COVID and a PHD without losing my mind. Maybe I'll switch to crossword puzzles.

[garcho]

the perfboard labelled them as C###

Most likely it's a capacitor then. And probably 100pF. Caps aren't usually axial like that, and even then they often have number codes printed on them, instead of color code stripes.

Just trying to find a hobby to weather COVID and a PHD without losing my mind.

Crosswords be damned! If your idea was that you can take apart random stuff and make guitar pedals, you might be a little disappointed, although there are certainly some fuzz/distortion/FSU kind of designs you could build with random components from old junk. Someone around here made a fuzz pedal from CFL light bulbs. For this to be satisfying, your expectations must be low.
If you get a breadboard and a few resistor and capacitor kits from eBay or similar, maybe a couple transistors and op amps, you don't have to spend much money and will be able to spend countless hours on this very addicting and rewarding hobby. If you have 50-ish bucks to spare, you'll be well on your way to making a number of guitar pedals. Want to make one, just to see if it's what you thought it was? Buy a kit, you can find any type of guitar pedal you want in kit form, again probably around 50 bucks. Need some recommendations for parts or projects? You're in the right spot! Welcome to the forum.

[jimbeaux]

The gimmick capacitor is also shown in Anderton's EPFM 2 - for "The Spluffer" project (splitter / buffer) 1 in / 2 outs (switchable)

It's 2 x 20 (or 22) gauge insulated solid core wire strands twisted 5 times - around a 1/2" long - supposed to be 5 pF

Schematically identical to C1 (10pF) shown in Mark Hammer's Three-Legged Quadrafuzz schematic.

Just guessing that it's there to keep stray interference out of the input.