Wanting to build a germanium fuzz face

[currang]

Hey guys, thought I'd make an account here to ask a couple of questions about building a pedal.

So I haven't built any pedals before however I have a little experience with a soldering iron and understand basic electronics. I've decided to build a germanium fuzz face since they are meant to be fairly straight forward, I don't, however, want to just buy one of those kits and just solder components on and have it done in no time as it just feels a little too easy... I'd prefer to use a strip board and find the components and build it that way as I like a challenge. I have a couple of questions though:
1) I've found a couple of places selling matched transistors for a fuzz face, one place is selling 2N404 germanium transistors and the other is selling AC128, from what I gather AC128's are more common but is there much of a difference between the two?
2) I'd quite like a mid/high gain fuzz face so what would you recommend for the hFE values of Q1 and Q2 and would these differ greatly between AC128s and 2N404s?
3) Last question, so I found an step by step guide on making a fuzz face pedal here: http://tonefiend.com/wp-content/uploads/Super-Fiend%20Fuzz%20Face.pdf and can understand most of it and feel it's pretty well explained, however I am a little confused with the wiring of the 3PDT footswitch. Does it matter what way round the lugs are so long as it is horrizontal? Like if the foot switch is rotated 180 degrees will it still do the same thing? I have found other places online with steps on wiring up the footswitch and they differ to the one on the site mentioned above so would just like to check.

Would be greatful if someone could help me out and apologies if some of these questions are a bit stupid but this is my first time building a pedal

Cheers!

[Brisance]

on #3, try to draw the schematic on the switch and translate to real life

[duck_arse]

currang - welcome to the forum.

if you wander over to geofex, linked at the top of the page, and look for the "technology of the fuzz face" article, it will tell you more than you think you need to know about them. read that, then read everything else there, then head over to AMZ, read some more stuff. there will be plenty explanations of 3pdt switches on the way.

+1 draw the switch. they are the easiest of all circuits.

[statzern]

Here's a great explanation for your switch question:
http://www.geofex.com/article_folders/bypass/bypass.htm

If the above is a little long-winded for what you are looking for, basically a 3PDT is 3 switches that are simulatneously switched. Think of it as 3 inputs (the poles) being routed to either of two corresponding outputs (the throws). Looking at the switch with the lugs horizontally oriented, the middle row are the inputs, and the top and bottom are the outputs. One state connects the middle row to the top row, the other to the bottom. Hope that helps!

Also, as far as bypass switching goes, study various schematics, but I would direct you to the General Guitar Gadgets Fuzz Face schematic for true bypass with LED switching capability. Simple, effective.

Welcome!

[mcknib]

It wouldn't really matter which type of germanium PNP you use but getting a matched pair is a good start between the 2 types you mention there's little difference with regard to this circuit.

Most matched pairs for sale will state the hFE normal range is from about 80 for Q1 up to 130 for Q2 with as low a leakage as you can get if it doesn't state it ask before you buy.

People use different methods for wiring their 3PDT  which are basically the same thing I use this method - Note the LED's wired for a negative ground circuit.

As you can see the lugs are horizontal middle row is common when connected to the top row it's in effects mode and bottom row bypass mode - more prattle here explaining it:

http://www.diystompboxes.com/smfforum/index.php?topic=111552.msg1027510#msg1027510

There's page upon page on the web regarding the fuzz face as you've probably discovered so RG's excellent technology of the fuzz face is a must read:

http://www.geofex.com/fxtech.htm

[smallbearelec]

Welcome to the Forum!

Full disclosure: I am both a long-time member here and a well-known vendor. I can help with providing information and parts, but the Fuzz Face is so well-characterized that you have numerous references and sources for components. I think you have noticed this by now.

The GEOFEX article is holy writ on the theory of the FF. I did an FAQ many years ago specifically on selecting transistors for it, and I have done my best to keep it current:
http://diy.smallbearelec.com/HowTos/FuzzFaceFAQ/FFFAQ.htm

That should help with understanding what is out there and something about what to expect when shopping.

Two basic suggestions:

--Breadboard First! The bias for the devices you buy might or might not need to be tweaked to make you happy, and the place to do this is on the breadboard, not on a PCB. This article:

http://diy.smallbearelec.com/HowTos/BreadboardSiFF/BreadboardSiFF.htm

explains how for an NPN silicon FF, but the information applies as well for germanium.

--Don't use stripboard or Vero for a first build. I don't use this material, even though I sell it. It's very popular, I think because you don't have to follow a schem to use it. I do not consider that a good thing; learning to follow a schem and wire point-to-point is an important basic.

More poop on stompbox-related land-mines:
http://diy.smallbearelec.com/HowTos/BeginnerArticle/BeginnerDos.htm

Have fun, and let us know how it goes.

[mcknib]

+1 on Smallbear's breadboard link it's a great tutorial for learning about the circuit as you build it

I was initially going to say build the NPN version because a lot of folks shy away from PNP versions because it's difficult to wrap your head around positive ground, it took me a while to get used to it even now I sometimes struggle.

[Elijah-Baley]

[...] I've decided to build a germanium fuzz face

Consider even a silicon Fuzz Face NPN, could be less tricky.

[...] I'd prefer to use a strip board and find the components and build it that way as I like a challenge

I build with stripboard, is simple enough for beginner and you can build on it quickly.

1) I've found a couple of places selling matched transistors for a fuzz face, one place is selling 2N404 germanium transistors and the other is selling AC128, from what I gather AC128's are more common but is there much of a difference between the two?

2N404 is a new production of AC128, it should be the same (I wish) or with identical characteristics. Actually, I don't know what differences could be between them, but if I'd choice AC128. Seems to me are becoming rather rare.
One year ago I ordered them from musikding.de, Germany, now are available just three "range of hfe" instead, I don't know... seven, eight...

[currang]

Thanks for the replies so far, I haven't yet gotten round to reading those articles but will definitely give them a look.

So I'm right in saying there are multiple correct ways to link up the 3PDT switch?

I quickly sketched the way I'm thinking of wiring the switch to the stripboard and was wondering if someone could have a look to see if they spot anything that is incorrect



I've got this wiring from having a look at the tonefiend link I sent in my first post, so long as the lugs on the switch are horizontal does it matter what way round it is?

[currang]

I realise I missed out the wire connecting the top left lug on the switch to the outermost lug on the input jack

[mcknib]

To make it easier when wiring switches it's best to visualise how the switch works to see if the connections you want are made

With this you can see that with throw 1 the purple lines (effects mode) 1 circuit input connects to 2 in jack tip, 4 LED cathode to 5 ground and 7 circuit output to 8 out jack tip so you're connecting the signal from your guitar via a cable to the in jack to the circuit input through the circuit to the circuit output to the out jack to the amp and of course lighting your LED to show it's active.

Thrown the other way throw 2 the red lines 2 connects to 3, 5 to 6 and 8 to 9 connecting the input jack tip and output jack tip directly together via the link between 3 and 9 bypassing the circuit and turning off the LED.

Apologies for all the waffle but it's required with the pic so you can visualise it as you read, anyway you know what I mean so looking at yours once you connect the in jack tip it looks like it'll work and now you can do a wee visualisation to make sure you've got your connections coz my head hurts! 

[duck_arse]

and no, as long as the lugs are horizontal, it doesn't matter which way is up.

[currang]

Thanks for all the info. I checked out musikding and it seems pretty good so might buy components etc. from there. I checked out its fuzz face kit and noticed it comes with a DC supply. Will the fuzz face work correctly with a DC supply (assuming it's wired up correctly) I know i can't daisy chain it but if I plug it into the mains will it work without burning my whole house down or anything like that? Its just I prefer using mains power since you don't need to worry about batteries running out etc.

[duck_arse]

I don't think there are many recorded cases of a fuzzface burning down a house. your plugpak should be safe, as long as you match your wall volts to their transformer volts ie don't connect a 110V AC tx to 240V AC mains.

if the fuzz face is positive ground, it can't be daisy-chain power-supplied with other negative ground effects, as the ground connection will short the supply. so you need a seperate supply, either a battery, a dedicated supply, or an internal inverter circuit, which can be powered by a daisy chain supply, and provides a negative rail for the FF.

[bool]

Well ... There are people who claim that a FF sounds better with a battery.

And that the type of battery matters as well -  the old carbon/zinc batteries should sound better than the alkalines. So, for the starters (and to keep things simple), it could be actually better to just stay with batteries.

Of course, having a PSU ready-to-go is always a good idea.

[FuzzFanatic71]

I would go with the 2n404 transistors. I built a Tonebender mkIII with them and it sounds real nice. My Fuzz Face has NOS AC128 transistors and it sounds great too. Maybe buy a set of each and put transistor sockets in your board with an external bias pot and see what sound you like best. Then you can use the other transistors and build another fuzz with them. You can never have too much fuzz.
And yeah batteries do sound much better than wall wart power, but I never use any batteries in my pedals. I like to be a friend to the planet. I don't judge people who do though so do what you feel is best for you.

[mcknib]

A battery will last in a fuzz face circuit it doesn't draw that much power + it's pure DC so will cause less noise.

If you're going for an adaptor it's important to use a properly regulated and filtered adaptor with a high gain circuit with a cheap unfiltered one you'll get unwanted noise.

As Duck_Arse says I usually put a voltage inverter circuit in my PNP pedals on a small piece of vero  so I can daisy chain them with my negative ground pedals.

Like this one:

[R.G.]

2N404 is a new production of AC128, it should be the same (I wish) or with identical characteristics. Actually, I don't know what differences could be between them, but if I'd choice AC128. Seems to me are becoming rather rare.

??
Do you have a reference for that?? I thought I'd plumbed through the history of germanium part numbers pretty well but never run onto that statement.

The "AC..." series was UK (maybe Euro too) type numbering, "2N" was USA numbering. The 2N404 was heavily used in computer logic circuits back in the mid 60s, but it does make a good fuzz face if you can find them and select the right gain and low enough leakage.

And that last clause applies to the AC128, and all other germaniums. Fuzz Face builders need to ignore the type number printed on the can. There is no magic in getting an "AC128" marked device if it's leaky or low gain; same for 2N404, 2SB..., NKT..., and other types. Ignore the type number. Either buy lots of them and test or buy pre-tested sets.

The entire planet has been pretty well scoured by effect builders and dealers looking for magic germanium transistors to make fuzz face clones. There are probably still little pockets and batches to be discovered, but the chances of a beginner finding them are small. I have found that batches of germaniums are often the rejected leavings of a dealer testing a large batch, then selling the ones that won't work well. If you plan to buy bulk batches, be prepared to lose most or all of your money on useless parts. This thinking is part of why dealers charge the prices they do - they throw away a lot of rejects.

Small Bear is a reliable source for pre-tested parts.

[Elijah-Baley]

2N404 is a new production of AC128, it should be the same (I wish) or with identical characteristics. Actually, I don't know what differences could be between them, but if I'd choice AC128. Seems to me are becoming rather rare.

??
Do you have a reference for that?? [...]

Actually, I got this information on the web from a pedal Diyers. I have absolutely no experience with this new transistor.

[PRR]

I'm sure the 2N404 and the AC128 are different roots.

They *are* similar specs and were (in the day) similar technology, but on different sides of an ocean, for different applications.

The '404 was (as said) aimed at big computer contracts (spec-sheet says "Computer Transistor", "data processing"). When computers went silicon, huge lots of surplus '404s hit the market. Mostly top-quality (though not tested for low-leak or low-hiss). All long gone now.

The '128 was aimed at "entertainment" uses (home radio, phono, TV), (data-sheet says "NF Transistor für Endstufen, für Gegentakt-B-Schaltungen" {AF Transistor for Power Amplifiers, for push-pull B circuits}). It appears to be Valvo's 2nd-source for Telefunken's AC105, which is a repackaged OC601, and goes back to GC1 in Jul 1953(!) which was in a glass bottle(!).

In fuzz work, I suspect '404 and '128 are generally more alike than different; and (as said) different '404 will work different, different '128 will work different, due to leakage and other individual differences.