WEM Project V, inductor question.

[digi2t]

I came across this pedal on "the other" forum.





So....
It's got a bunch of BC108's 
It's old 
It's obscure 
and did I mention that it's got a bunch of BC108's in it? 7 to be exact, plus a BC186. (sorry, no drool smiley)

So, I'm in for a breadboard shot, but....

Other than a component or two that could be figured out on the fly, there's one thing that I've never seen before. An inductor between the emitter of one tranny, and the base of the next (transistors 1 and 2)



An analysis of this (posted by grizzlytone) states;
"*it makes perfect sense to protect the input of the AF amp in a transistor radio from RF signals that could otherwise modulate the AF signal. This is accomplished by means of the HF inductor in series at the i/p stage. The HF-inuctor is marked "R.C." for R.C. Components (still in business) and should not measure more than say 15 ohms DC resistance and the inductance is most likely in the uH range. It is not meant to have any impact on audible frequencies (try replacing with a straight piece of wire on a prototype)"

So I'm wondering what our house gurus think about this. Should I skip it with a jumper, or should I try something specific here. I'm just not familiar with an inductor used in this configuration. I've only dealt with inductors in wahs.

On another note, any suggestions for a good sub for the BC186? They're pretty pricey.

I would appreciate any educated guess. I don't mind being the guinea pig here.

Cheers,
Dino

[digi2t]

Alright, I've ditched the inductor, and gone direct there. There was an error with the first diagram, so here is the corrected one;



Rather than use up a good chunk of my BC108's or 109's, I'm running 2N5088's and a 2N3406. Between the 8 trannies, and the two trimmers, it's like trying to tame a bunch of wild cats. I did steal a little trick from the Axis Face, and inserted a 220pF silver mica cap between Base and Collector on tranny 5 (PNP). It helps to tame the really harsh high frequencies coming from that part of the circuit, and allows me to tune it much closer to the calculated voltages without getting into "constant buzz-tone" territory. Kind of smooths things out a bit, less fizzy.

I've got the main voltages set at 1.55 for Q3, 3.55 for Q5, and 5.12 for Q7. I seem to get the best fuzz/tone to noise ratio here, although the noise should drop when it's boxed, and the shielded wires are in the equation. What I'm running right now is 2N5088's, and a 2N3906. All in all... I like. Not for the faint of heart, but rewarding when you get everything reigned in.

This is one, ummm, special fuzz. According to some, Brian Eno used one way back when. So, here's what it sounds like on the breadboard;

When it's dialed in, it sounds pretty decent.

[LaceSensor]

Anyone doing any form of layout to your knowledge?

[digi2t]

I'm planning a vero at some point. I like this sucker. I just need to get the resistors and caps around the drive/edge switches validated. The Drive switch seems to reverse when the Edge is off. I don't know if this normal, or if there is something missed in the dissection. Once I figure this out, I'll whip out a vero, although I may make some mods i.e. tone knob, and reroute the Attack section so it goes from clean to fuzz, instead of from zero to full fuzz. I find the Attack knob subbing as a volume as well, somewhat redundant.

Considering what a hen's tooth this is, some fine people did some mighty fine work to R.E. this baby. It deserves to be ressurected.

[RonaldB]

Thanks for the video,
sound like a good fuzz.

RonaldB

[LaceSensor]

I'm planning a vero at some point. I like this sucker. I just need to get the resistors and caps around the drive/edge switches validated. The Drive switch seems to reverse when the Edge is off. I don't know if this normal, or if there is something missed in the dissection. Once I figure this out, I'll whip out a vero, although I may make some mods i.e. tone knob, and reroute the Attack section so it goes from clean to fuzz, instead of from zero to full fuzz. I find the Attack knob subbing as a volume as well, somewhat redundant.

Considering what a hen's tooth this is, some fine people did some mighty fine work to R.E. this baby. It deserves to be ressurected.

I would like to build one and would like to help with the vero.
I have a friend in an upcoming band that is hoping to cop the Eno tone, so an vero would be amazing.

[digi2t]

Give me a couple of weeks. I'm kinda loaded right now, but I'll come up with something.

I'll warn you right now though, I'm planning on using 2.5uF axial caps, as per the original. They'll take up a bit more room, but it'll be more authentic.

[glops]

Sounds fantastic, thanks!!!