Anyone know what this is?
(http://www.basicaudio.net/Mystery-part.jpg)
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.
Quote from: John Lyons on February 14, 2010, 12:11:39 AM
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?
QuoteIt'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?
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...
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.
Its a diode John. You can see the cathode end with the black stripe across it.
Quote from: Pedal love on February 14, 2010, 01:52:47 AM
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.
I don't think it's a diode.
(http://www.basicaudio.net/Mystery-part2.jpg)
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
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.
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?
Its a diode.:icon_evil:
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?
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
(http://www009.upp.so-net.ne.jp/GrandFunkManiac/images/Mark_Mod050.jpg)
The mystery component is marked as D1 in the (one year old) preliminary schematic from Sat Jan 03, 2009:
(http://analogguru.an.ohost.de/temp/Messenger_Fuzz.gif)
Quote from: R.G.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
double post
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.
Well it might be a resistor, but it will definitely be the first inductor I have seen in a fuzz-q1 emitter to ground.
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.
Quote from: Skruffyhound on February 14, 2010, 09:28:08 AM
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
So two people named skruffy have have inductors like this...It's gotta be right :icon_biggrin:
Yep messenger fuzz. No fooling AG....
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
Quote from: Pedal love on February 14, 2010, 06:48:04 AM
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.
Quote from: R.G. on February 14, 2010, 02:59:06 PM
QuoteLike I said, I don't really know, can't tell from the photo.
Well put.
I agree about diodes there not allowing an output, but it sounds like some of you guys are saying no circuit can work with a diode like this in any way- thats wrong.
Sorry Analogguru, I wasn't having a dig at you, I just read the post as if it was the manufacturer's schem not a reverse.
When you talk about a circuit that has a part that is undefined there are many variables that simply exist. Need more info guys.
Coil may be unusual, but not pointless.
If you just bias-up a grounded-emitter transistor, and hang wire (AKA guitar cord) off the base, it will pickup every strong radio station in town. A naked junction will rectify anything over about 20mV. Local broadcast radio in a few yards of antenna tends to be 2mV to 200mV. AM radio demodulates with simple rectification.
An awful lot of simple naked-transistor stomps have quite large resistors between base and external antenna. That against base impedance will cut both radio and guitar, a bit more radio-cut than guitar cut due to base capacitance.
If the posted plan is slightly right, this designer uses a fairly small series base resistor. And maybe got the local MoR AM radio, or garble from truck CB (if anybody still has CB?). Even, very likely, hash when the cellphone does its things. (I don't leave my cellfone next to my clock/radio any more, it makes nasty static in the middle of the night.)
"I say", ignoring Dirty Tricks, it looks like a thousand uH coil.
HERE is a picture (http://media.digikey.com/photos/Bourns%20Photos/5200%20SERIES.jpg) of a high-current choke of similar construction. Use a smaller core, one layer of much smaller red wire, it's about the same.
To "do something" it must act larger than Q1 junction, which I estimate near 600 ohms. 1000uH at 1MHz is 1,000 ohms. If this eyeball estimate is correct, it does nothing below 500KHz. You may breadboard for audio with a short. If RF is a problem, try 1,000uH coil.
This is the circuit in question.
(http://analogguru.an.ohost.de/temp/Messenger_Fuzz.gif)
All of the parts are accounted for except the inductor (or whatever it is).
I have traced the board top and bottom from pics.
Thanks for the reasoning Paul.
The coil may be omitable I take it. Seems likely as an interferance band aid
against radio... Much simpler to work that out with an input ferrite bead of cap/resistor
if need be.
Quote from: John Lyons on February 14, 2010, 08:41:30 PM
The coil may be omitable I take it. Seems likely as an interferance band aid
against radio... Much simpler to work that out with an input ferrite bead of cap/resistor
if need be.
With only eight resistors, four caps, two transistors, the simple thing to do is to build it
and try it, whether real or in a simulator. Sub in diodes, caps, shorts, and inductors
for the mystery part and see what makes it look like it's working.
I've built it on the breadboard. It sounded like crap (in an bad way :).
I need to try some other transistor gains etc.
one of the guitar sounds that made me so excited to be a guitar player when i was 14 was the flanged out fuzzed out solo on grand funk's radio hit remake of 'locomotion'.
john if you can get this circuit to sound like this, you are my new hero.
solo starts at 1:17 - fasten your harness!
http://www.youtube.com/watch?v=jxyU4W8iyeI
Ha! Yeah, that sounds like your kind of tone/solo/feeling Joe!
Cool stuff. I guess I need to put on my breadboard hat for a bit.
> It sounded like crap (in an bad way)
Not a shock. The biasing doesn't "force" transistors to any specific operating point. Changing simulated transistors (even for types I would call "interchangable" in most circuits) gives quite different op-point. Battery drop changes bias violently; good thing it pulls nearly no current, and a dry cell will give shelf-life. Temperature effects are strong, though I guess the player will faint before the biasing does. (Would not be my first choice for New Year or July 4th shows.)
Have you IDed the transistor material and hFE-zone?
As a sanity-check: collectors should sit significantly below 1.5V (I got plausable waveforms with 1.3V and 1.1V), yet probably more than a few tenths volt above ground. Really-crappy suggests the darn thing is jammed-up, or just miswired.
There's some interesting interactions. Q2 input resistance is 10K-30K, a very heavy load on Q1's 22K for up-swing. Q1 can pull-down far better, but in sustained overdrive of course charge must equalize so C3's voltage will shift. That cap may be sized for the speed/dynamic of guitar and inventor's taste, and a very different cap may give a very different sound.
C2 is either a treble roll-off or an RF cap. A plan like this probably wants some fizz rounding, so that may need to be in a certain zone.
Did you copy the layout very-very well?
This thing has a lot of gain and (unlike simpler stomps) is non-inverting. If output gets to input, it will oscillate. If you don't hear that, it squals above the audio band. That may be why the emitter choke, and why that choke is laid-out quite oddly down the length of the board instead of like the other emitter resistor.
I'll try it again and report back.
From the first attempt it was dull and anemic
not much fuzz at all. With this new insight I'll
see what I get and maybe I has something
miswired in the breadboard.
Again Paul, thanks for the ideas.
O.K. everyone, If you want to see this very circuit board in action it's on youtube now: http://www.youtube.com/watch?v=m5EJUFVptHo or just type in MESSENGER FUZZ it's posted by spacetonemusic For this video the guitar is being used with just a solid state Peavy practice amp but you get the idea. And YES this is the guitar that has the very exact circuit being post by John Lyons
Sounds good. That sounds like the sound we want.
Not mind blowing but it sounds like the grand funk sound.
thanks for that clip!
John
Also on that youtube video it's just the tiny microphone on a digital camera. In person with any good tube amp the fuzz is mind blowing. It gets all the Grand Funk Railroad sounds and it can do a whole lot more.
Yeah, I agree, it sounds good. Especially considering the mic and amp...
thanks for posting that. Can you give us some info on the guitar?
It seems like a repro messenger. Is is old?
No way a reissue. Original 1960s Messenger Magna with no sound holes. How many Magnas has anyone seen before? The Magna was only listed in one of their 2 catalogs. Previously owned by the guitar player for Helloween in Germany and he is a Mark Farner fan. Don't know if he did the changes: bridge, tuners, and re fret with jumbo frets. Some experts say finish is original and some say overspray but absolutely original color. There is metallic green paint under the serial number label on the inside.
That's why I asked...the guitar looks in great shape!
I remember Helloween ;)
There is some natural weather checking that doesn't show on the video. Also though some Messengers did have a Bigsby tailpiece, this one was most likely added.........
I'm getting emails about the Magna saying there's no such Messenger and posts on another saying the same thing. Here's one in their catalog.
http://home.g09.itscom.net/gfr1212/otakara/images/Eric_Collection02.jpg
Quote from: John Lyons on February 15, 2010, 02:23:55 AM
I'll try it again and report back.
From the first attempt it was dull and anemic
not much fuzz at all. With this new insight I'll
see what I get and maybe I has something
miswired in the breadboard.
Again Paul, thanks for the ideas.
Hey John. Did you ever have a chance to try this circuit out again? I threw it together on the breadboard and only got a light overdrive. Unimpressive. Nothing like in the video pygmygoatllama kindly posted. Is there anyway that this circuit could be wired to a pot that acts as a fuzz intensity control? It felt this way to me.
reviving an old post here, john did you ever et this working and sounding 'good' it seems like an interesting projet, but im wondering about which transistors to use, and about the inductor/resistor/diode/plutonium part.. :P