Ge FuzzFace schematic I drew,...Errors? Update of layout,....

[formerMember1]

Hi,
I am going to venture into the part of stompbox building of designing my own layouts. I always used layouts online, but want to make my own.  Well i  downloaded express pcb, and have drew a schematic for a Germanium NPN fuzzface.  I added a 50k input pot(bias from fulltone), and made the 33k and 8.2k trimpots, polarity protection and power filtering,  etc,...I figure the next step would be to draw the layout using my Schematic i drew.  BUt was wondering if anyone could take a quick glance at the scheme, and see if i made any mistakes?

I have looked it over many many times for error.  BUt since it is my first time, i want to get a second opinion from you guys.

This is my first time posting a pic in the forum, so it is a little small, if anyone knows how i could resize it so it doesn't hurt your eyes, please tell me.
(i used photobucket as advised in the "about this forum" thread from Aron.) (the pic was automatically resized by photobucket, no matter what i did)




Do i have the power filter and diode oriented inthe right direction?  I am going to use NP electro for the 20uf and 2.2uf.
Anything i should do differently?

I apologize for being so small, and if this is aggervating.  I don't know how to resize it.

thanks

PS:i will post a pic of the layout, in a few days if that is OK?  Or maybe should i delete this post, and put it in the beginner forum?

**EDIT**
changed to poalrized 2.2 and 20uf, and also made it say 50k and 20k trimpots and 1n34a temp diode,...
thanks guys,...

[petemoore]

  Nope, I don't see any, Nice Job !

[Steben]

You could cut out the blank border parts in the pic  Maybe PhBucket will resize to the same measures, resulting in a larger schematic?
Still, it is readable. No errors. I wonder why you would use NP? Because you have them? If not, you don't have to buy such caps if you can buy normal ones. It's a fuzz after all.

[petemoore]

  Non Polar is nice, for those FF's that are yet undecided on which polarity to go with.

[MartyMart]

Nice job, just call the trim pots 50k and 10k - standard values.
I would show polarity on the large caps, 2u2 and 22uf like you have
on your 100uf.

Marty 

[Steben]

  Non Polar is nice, for those FF's that are yet undecided on which polarity to go with.

Ok, I'm tuned in. Yet all caps should be NP then and trannies socketed, right 

[formerMember1]

thanks guys 

I will change the R's to 20k and 50k trimpots, make 2.2uf and 20uf polarized, added 1n34a temp diode,...

thanks again,..


PS:someone sent me an email, of a resized picture, but photobucket ended up just shrinking it again.  I did cut out the blank space too, but no cigar.

[formerMember1]

hey guys, i am having serious trouble making a layout for my above schematic. 

Is it possible to import phillip's layout for a fuzzface,  http://fuzzcentral.tripod.com/fuzzface/fuzzfacepcb.gif

http://fuzzcentral.tripod.com/fuzzface/fuzzfacelayout.gif

and just add my few parts to the layout, and change it too NPN?

I only want to add a 50k pot at the input, and make the 33k and 8.2k a 50k and 20k trimpot, a power filter, and a polarity protection that is the only "mods" to his layout.  :icon_wink:  (maybe a 1M pulldown at the input too, But i don't know yet if i am gonna use a grounded input true bypass wiring or not,.. cuz i always get POPs on my pedals, i am thinking grounded input will solve it)

I tried numerous times, (3-4hours), but will try more,...

[Steben]

A lot of the stuff you want can be done off-board, isn't it. 50k pot... Pulldown resistor on the switch or so?

Stabilizer diode can be soldered on existing lugs of the transistor, but beware: GE diodes are made of very fragile glass.

By the way: the stabilizer cap isn't necessary if you only use batteries. And a FF dooesn't draw a lot of current at all.

[formerMember1]

Yeah, i could probably put some of the those parts off board, but i figured i might as well put them on the board, cuz i am using a 1590b hammond box, so i  don't know if i would have room for offboard components.  But, now that you mention it, maybe i should add the few parts off board.

But then again, i was making my own layout, so that i could make the 33k and the 8.2k a trim pot, so i figure i might as well put the rest of the parts on the board, for ease of use.

Yeah, i know the diode could be soldered too the leads of the transistor, i just thought it would be safer to not possibly ruin the ge tranny.

I will be using both an adaptor and battery, so i would need the 100uf cap.

thanks for your help steben. 

PS:so do you think that i don't need a trimpots, for the biasing if i use the temp diode trick?  Cuz the reason i was gonna use trimpots, was becuase i wanted to be able to leave the 8.2k stock and use the 33k to bias, then vice versa, so i could dial in what i want.  PLus, incase i was playing out, and the fuzz sounded bad cuz of the temp there, i figured i could at least fix it by rebiasing it.  BUt, then do i really need to worry about that since i am putting a temp stabilizer reverse biased diode in there?  I talked to someone else about it, but they said the temp diode only helps a little, i forgot to ask them about if i still need trimpots to help in different temps,....?

[Steben]

Well, we kinda agree all in here: you don't need two trimpots. The 33k can be a fixed one.
But the 10k trimmer should be there if you wanna fine tune your FF (collector Q2 to 4.5V-5V), unless you're sure about the transistors' gain.
You see with GE trannies it's far from being the case. The 8.2k value is good for the GE devices with a certain gain, but only a few are exactly that gain. That's why some non-trimmed FF's sound good, some bad. With a trimmer you adapt the circuit to the trannies.
The stabilizer diode is there to ensure the bias point you have set, but it doesn't choose it on it's own, you see?

And my god you haven't got luck with photobucket...

[formerMember1]

oh jeez, i am sorry steben, i must have come across the wrong way.

I understand the whole thing about biasing Ge etc,...I built a Ge rangemaster, i also built a great sounding Axis Face Silicon Rev 3,(made to sound like Germanium) and a clyde mccoy that i am still tweaking, it is just that now i want to build a real Ge fuzzface, to compare to the Axis Face, and also to play/have. 

what i meant about the 33k trim and 8.2k trim is this:

I always biased the fuzzface with a 8.2k trim, and get 4.50volts on q2 collector.  I liked it. But then Fretwire, taught me how to bias the fuzzface by the 33k instead. When biasing the Fuzzface by making the 33k a trimpot, and leaving the 8.2k stock, it sounds way different than biasing by 8.2k.

THe reason i wanted both 8.2k and 33k to be trim pots, is i was gonna mark the 20k and 50k pots for 8.2k and 33k, then turn 33k until it is biased, play/hear, then turn back to 33k, and change the 8.2k to bias. Play/hear.  I want to make the 8.2k a 20k not 10k, because i want to try the mayer mods also(18k) That is why in the scheme it says 1k/2k for the fuzzpot,... cuz i am gonna try mayer mods, normal biasing by 8.2k and biasing by 33k. 

As far as the power filter,temp diode,Polarity Protection, etc,... i want them on the board for ease of wiring up, i will be building multiples of the pedal.  Always using a 1590b hammond.

My reason for posting this thread, was because I always used  a  layout online, but can't find one with all those extra things i wanted on it.(PF, PP, Temp, 50k trim and 20k trim, etc),  So i figured i would write my own schematic with expresSCH. and then use the schematic to make my own layout with expressPCB.  I am done with the schematic and checked it for errors, by you guys, me and the program.  BUt now when i am trying to make it into a layout, i am having trouble, but i will keep trying, it will soon sink in.  I just have trouble making it efficent etc,..but that is the whole learning process to it, since i searched/read on the forum, that you need to keep at the layout, until you learn to make a good one. 

thanks for taking the time to help and i am sorry i confused ya, 
i always have trouble writing stuff down,... 

[formerMember1]

And my god you haven't got luck with photobucket...

what do you mean?

(i did try posting that picture to photobucket like ten times, but it always stayed small on me.  what i did was hit printscreen and pasted the scheme in the paint program, then trimmed it and saved it, uploaded it etc...I did trim it, but it always keeps that border around it, and it makes the pic small on me.

[Fret Wire]

Well, we kinda agree all in here: you don't need two trimpots. The 33k can be a fixed one.

Hardly. Who is the "we" that dictates this? Q1's collector frequently needs adjustment for optimum bias. There does seem to be a school of thought that seems to think that as long as Q1's emitter is 0v, and Q2's collector is 4.5v, you are properly biased. You'll almost never get optimum biasing this way. There are 7 voltages you need to be mindfull of when biasing (battery & 6-tranny) a Dallas fuzz. Both Q1 and Q2's collector usually need to be adjusted, Q2 alone will not usually do it.

But the 10k trimmer should be there if you wanna fine tune your FF (collector Q2 to 4.5V-5V), unless you're sure about the transistors' gain

10k will be useless with the Mayer mods (1k output & 2k fuzz pot), which usually need around 15-20k on Q2's collector. 25k is a much better choice if you want a trimmer on Q2. 75k is a better choice for Q1 than 50k if you are using gains outside of the 70-120 range.

That's why some non-trimmed FF's sound good, some bad.

Not true. For DIY, many of us use a dedicated fuzz jig or temporary pots to determine bias, then install fixed value resistors. The original and reissue Dallas's do have fixed value collector resistors, and more often than not, the 8k2 and 33k don't work well with the trannys that were randomly installed in them. It's the biasing values that count, not whether you use trimmers, pots, or fixed resistors to achieve them.

The stabilizer diode is there to ensure the bias point you have set, but it doesn't choose it on it's own, you see?

Right, it does add some temperature tolerance, but it isn't perfect. You won't be able to play in the Sahara Desert without your fuzz crapping out. Btw, Ritchie, you need to set the bias with the temp diode installed.

[formerMember1]

i will change my trimpots to 25k and 75k then,..just incase i get a little out of the "right" range for the hfe.

Btw, Ritchie, you need to set the bias with the temp diode installed.

Thanks FretWire!!   

[RDV]

If you convert the bitmaps you're drawing to a JPEG or JIF, then Photobucket will take it 'as is'. It's not image size, but file size that makes the difference.

HTH

RDV

[formerMember1]

 

[formerMember1]

hi,

I am ready to print my layout on PNP to make board, but i was wondering if the traces are too thick? They are .080" traces from the pcbexpress.  Should i use .060".

I didn't know if too thick of traces might cause problems for some reason.  It is perfect size for hammond 1590b box.



thanks 

PS:don't have both transistors shown.(that tranny is not being used,)  And that is just heatshrink that is too big,..(ran out of small heatshrink)
the layout is a form of fuzzcentrals, but adapted with other parts/trimpots etc,...

[no one ever]

i don't think too thick is a problem.. but i wouldn't know, i'm using .51mm traces on my spst tb project.


how'd you get the traces to print out like that formerMember1?

[Peter Snowberg]

Thicker = Better.

Etch away!