Popular Mechanics May 1979 FUZZ

[Voltron]

Hello, here's a fuzz circuit originally published on PM mag on may 1979.



I'm posting this as maybe someone else is searching for this o maybe someone want give it a try. I found another thread with someone asking for this but I came many years later.

Let me see, if I learned anything from looking at so many schematics on the internet: Input stage around Q1 is a linear boost, follows a coupling resistor+cap and the diode pair to ground which hard clips but has pot control and at the end the output stage around Q2 which maybe has missing resistor?

SOrry I coudn't find it the english version
http://www.mimecanicapopular.com/verhaga.php?n=549

By the way, what's going on with the forum gallery?. I can't recover my pass login to upload.

[nocentelli]

Q2 looks like a buffer stage only, so shouldn't need a collector resistor. However, since it's negative ground, the use of pnp transistors here confuses me.

[Keppy]

Q2 looks like a buffer stage only, so shouldn't need a collector resistor. However, since it's negative ground, the use of pnp transistors here confuses me.

Google says they're both NPN, so it appears the symbols are misprinted. The mystery to me is why bother making C2 non-polarized? Is there any real danger of building a positive charge when S1 is open?

[mac]

It looks like an Electra distortion with an output buffer @ 3v

Google says they're both NPN, so it appears the symbols are misprinted.

B1, B2, C5, C1 point to NPN too.

The mystery to me is why bother making C2 non-polarized?

And so big. I bet a 0.22uf, like C3, is fine.

SOrry I coudn't find it the english version
http://www.mimecanicapopular.com/verhaga.php?n=549

En español esta bien para mi

mac

[Güero]

[PRR]

[PRR]

IMHO---

The transistors can be "any" NPN. As long as they are not sick it will work and very much like the original (as if we knew it was good; it may have just been a magazine page-filler).

The only reason I see for Q1 different than Q2 is that, at the time, there was a difference in cost. Q1 can use some gain, Q2 hardly needs any, so why pay 50 cents more? These days in DIY, I would use 2N2222 or 2N3904 in both. Check pin-outs.

Medium-hFE is most-like the original types.

Silicon is specified but not essential. SmallBear has some stock of NPN Germanium if you want to try that.

Agree that C2 could be 1uFd polar (+ toward R5). C3 does compute to about 0.2u for full deep bass (Q2's input could be as low as 50K); 0.1u would be ample for guitar.

I'm undecided about C1. Q1 input could be 5K or less, so with R1 10K we pick 1uFd for full bass. For guitar distortion a smaller value might be less muddy.

Pot R9 can probably be linear.

Pot R10 is ideally reverse-audio taper, but 10K linear is a good starting point.

[antonis]

A bit of current consumable, I think..

No pot for Gain but pot for clipping threashold..

[Davelectro]

This circuit is very similar to the Sam Ash / Astrotone Fuzz. The biggest difference is the variable clipping threshold.

[PRR]

> variable clipping threshold.

Not threshold (start of clipping).

Softness (abrupt or gentle clipping).

[Davelectro]

You're right.

Clipping actually starts at the same point.

[LucifersTrip]

btw, it's similar to the Sam Ash/Astrotone without the tone control...

[Davelectro]

Yeah. Worst tone control ever. 

Not needed at all IMO.

[Voltron]

Cool. So knowlageable people, never tired of your circuit insights.

Oh that Sam Ash tone control has no separation from volume and they both interact each other too much, right?, I think I've seen it in an old jap fuzz and some old tube small amp, If I remember?. On a second thought, that might give you some advantages from a simpler overdrive circuit like this (as in lots of variatons from less controls) ?

Most likely the magazine fuzz was based on sam ash fuzz mods.

Maybe put this in together to build the "Popular Fuzz"
http://www.swtpc.com/mholley/PopularElectronics/Feb1968/PE_Feb_1968_pg42.jpg

[Davelectro]

Although the astrotone tone control works a bit better than the original (Sam Ash), IMO it's not good enough to justify the additional potentiometer.

I'd rather use a trimpot there. Set and forget.