I have a TON of small inductors

[burdt]

I recently revived the old creative enclosures thread after i stumbled upon a box full of directional couplers at my university's surplus sale. (see http://www.diystompboxes.com/smfforum/index.php?topic=60466.20 )

Tonight i finally removed all the circuit boards from the boxes and identified what i could salvage. I scored a lot of capacitors and since i'm a nerd here's an inventory:

poly film

.47uf orange 10% 400v 24
.047uf assorted 10% 400v 24

silver mica (all 300v)

621 5% 6
122 5% 3
620 5% 6
1200 5% 3
820 5% 17
910 5% 12

ceramic

103 16X3
100 6
33  6

However, the caps aren't the problem. The problem is all the inductors i found. There's probably about 50 smallish inductors all along the boards and i don't know what to do with them. I'd love to salvage them and build something useful, but i don't see inductors very often in bills of materials.  Additionally, i don't know how to deduce their value. I'm hoping y'all can help me out. here's a handful of blurry iphone pictures:









You probably wont be able to tell me the inductor values from the blurry ass pictures. However, you might be able to point me in the right direction regarding how these components are used. According to wikipedia inductors "form tuned circuits which can emphasize or filter out specific signal frequencies." A quick search of the forum gave me a few possible uses for them in eqs, amps, and wahs .

What i'd like to know is how to breadboard some of the possible tone circuits inductors allow. A knotch filter would be awesome before/after a dirt pedal, something like a "Rooster-ed wah in a box" achieved by an inductor eq. or a hum eliminator built into a high gain box that you can switch on when you're around florescent lights.

This is all speculation though since I'm not even sure what is possible with the values i scavenged, let alone inductors as a whole, but at least i'll learn something new today. 

Thanks.

[earthtonesaudio]

The looks of those, coupled with the small value of most of the caps, leads me to believe they are high current RF chokes, probably with values in the low microhenry range if not nanohenries.

Essentially you'd be very hard-pressed to find a stompbox schematic that could use them.  Radio or video frequency stuff possibly, or (less likely) some switchmode power supply applications.

[brett]

Hi
have a look at various filters.
You can make some cool resonant circuits with RLC systems (searcxh for wahs, DC-DC converters, etc). Check wikipedia for the formulae relating freq to R, L and C.
If you can get hold of a scope, you can estimate the value of a wah by making an RLC circuit with known R and C, and sweeping the input frequency to find the maximum or minimum output.  Then use the formula to calculate L.
good luck

[Mick Bailey]

The values are too low to be useful at audio frequencies, though I've used similar sized cores for Nixie high voltage power supplies when rewound. Apart from Wah circuits, there aren't too many pedals that feature inductors. With the correct inductor value you could make a Gibson Vari-tone in a pedal form and add some op-amp recovery. Similarly, Craig Anderton's Passive Tone Control uses an inductor. This design also works better with some op-amp input gain as well as an output buffer.

Having said that, you would need to rewind the cores with a considerable number of turns of fine enamelled wire (as well as gluing on some bobbin ends) to get the value required. Probably not worth the effort unless you're really keen on experimenting with inductors and have a lot of patience.   

[edvard]

Man, you could build an awful lot of burst boxes with those...

[MarcoMike]

 

is there any chance you have some 5 - 10 mH inductors there?

(or does anybody know where to find some?? also variable Ls in the range 50 - 100mA...)