Mystery component...

[John Lyons]

Anyone know what this is?



I guess it's an inductor but...
It's connected to the emitter of a transistor
in the typical emiter resistor fashion with a BJT.

[R.G.]

Anyone know what this is?
I guess it's an inductor but...

You're probably right. What does it measure at DC with a meter?
Capacitance meter?
Resonance with a known capacitor?

It's connected to the emitter of a transistor
in the typical emiter resistor fashion with a BJT.

OK. Why might we want an inductor in an emitter?

[John Lyons]

The problem is that I don't have the circuit in hand.
I'm just trying to figure it out from the photo 

Your best guess is better than mine R.G.
I'm not sure why the inductor would work or how in this
position. I know they have some resistance but...

[sean k]

Bass boost? It shares both a resitance to ground and an impedance to high freqiencies and no impedance to lows so the lows disappear, as it were and the highs remain as negative feedback... so bass is boosted...depending on resonance, maybe even low mids.

[Pedal love]

Its a diode John. You can see the cathode end with the black stripe across it.

[R.G.]

Its a diode John. You can see the cathode end with the black stripe across it.

Maybe. I can't quite tell from the photo, but it looked very much to me like some ferrite inductors I've seen with very fine copper wire wound on the ferrite (the red stuff on the body) with ferrite protruding from the end. Anyway, it looked more like a tiny inductor than a diode to me.

Could be a diode, I guess.

[John Lyons]

I don't think it's a diode.



The package is not rounded at the corners as diodes are, and the size is
bigger than any glass bodied silicon diode. Those are 1/2 watt resistors by the way.
The black ends are symetrical so I don't think it's a cathode stripe designation.

So if this is an inductor what would your best guess be as a starting place
as far as values to try?
This is a vintage fuzz circuit for guitar. Sorry to be so cryptic but....

Thanks for the help chaps.

John

[Dan N]

I've seen little inductors that looked like that too.

I can't understand why you don't mention the fuzz it comes from, but I'll respect that and keep my trap shut.

[Scruffie]

I don't know what value it is either but i'm pretty sure i've got a bunch of those sized inductors salvaged from some 60s gear if you wanna have them and try them out?

[Pedal love]

Its a diode.

[Pedal love]

John please try to listen.

1) How many times have you seen a diode in a fuzz circuit?
2)How many times have you seen an inductor in a fuzz circuit?

[analogguru]

I would suggest that this is from the (Grand Funk Railroad) Musicraft - Messenger Fuzz:

http://www009.upp.so-net.ne.jp/GrandFunkManiac/Mark_MOD.htm#FUZZ



The mystery component is marked as D1 in the (one year old) preliminary schematic from Sat Jan 03, 2009:

OK. Why might we want an inductor in an emitter?

A coil at this place would reduce the gain of the first stage at higher frequencies (only) - which would make (more) sense (than a diode) -  just short it out (for the first test).

BTW, the cap values appear to be:
C1 (input) 47n or 100n
C2 (C-B of Q1) 47p - 100p (not important)
C3 (coupling electrolytic) 1µF - 10µF (not important)
C4 (output cap) 1n - 10n (importance depending on the value of the following poti)

analogguru

[analogguru]

double post

[teemuk]

The posted circuit - having such low supply voltage - would not even bias properly and work correctly with the diode in the emitter.

Inductor makes way more sense.

[Pedal love]

Well it might be a resistor, but it will definitely be the first inductor I have seen in a fuzz-q1 emitter to ground.

[Skruffyhound]

I've also got a bunch of little inductors that look just like that. Can't tell you why it's there, but I'd love to know the answer if you find out. Wouldn't be the first time a schematic was not entirely honest.

[analogguru]

Wouldn't be the first time a schematic was not entirely honest.

I assume that "PRELIMINARY SCHEMATIC" is not a foreign word to you.

analogguru

[John Lyons]

So two people named skruffy have have inductors like this...It's gotta be right
Yep messenger fuzz. No fooling AG....

[analogguru]

More info and discussion can be found on the first hit:

http://www.google.com/search?as_q=musicraft+messenger+fuzz&hl=de&num=10&btnG=Google-Suche&as_epq=&as_oq=&as_eq=&lr=&cr=&as_ft=i&as_filetype=&as_qdr=all&as_occt=any&as_dt=i&as_sitesearch=&as_rights=&safe=images

analogguru

[R.G.]

Well it might be a resistor, but it will definitely be the first inductor I have seen in a fuzz-q1 emitter to ground.

Like I said, I don't really know, can't tell from the photo.

Of course, I would have said that zebras don't live in Texas, but then I saw my first live zebra in Texas by driving about five miles west on the road I live on. The guy who owns the place likes zebras and has the money to buy them and to get the necessary licenses. It was definitely the first zebras I'd seen on ranches in rural Texas.

For some interesting side-information about why things are not always as they appear, read "Dirty Tricks 101" at geofex if you haven't already. Along those lines it might really *be* a diode - but a hand-selected previously damaged one which now conducts like a short circuit. Or those leads could be a straight wire through the body, and the outsides are just decorations.