first build issues…

[karsten_h]

hi everyone out there... newbee to building stompboxes and fiddling around with electronics, during the last days i built my beavisboard and as first set up a FF circuit on breadboard, seems to work got through some mistakes but could troubleshoot them. BUT the circuit only seems to catche a signal from my guitar (squier tele 4way switch) at highest output... wanted to solve and work around that by adding a gain LPB1 circuit in front and here the same... does not seem to matter which combination and/or type of transistors i use, tried various silicon high gain and some germanium midle/low gain i got in stock... any suggestions out there? thx for your support!

[GibsonGM]

Hi Karsten, Welcome!

"BUT the circuit only seems to catche a signal from my guitar (squier tele 4way switch) at highest output..."

Does it make gated, farting sounds?  Sounds like a biasing problem more than anything else.  If adjusted properly, a FF will be 'on' all the time and not that sensitive to input level.  Do a search here for 'biasing fuzz face' and see if you can get started understanding 'biasing', and we can probably walk you thru a lot of it.    You could provide the FF schematic you used, and what transistors, etc, too, please  

[karsten_h]

thx for your reply, allready did some research and measuring of the voltages in the circuit and they seem quite out of bias - yes!
I got a 10K trimpot here but no 100K to substitute the resistors, i will get that soon and then work thru... besides i will check the actual transistor leakages and real gain to get a better idea of them... wat to use some russian germaniums i got from ebay 10pieces 404A and 404B: https://alltransistors.com/adv/pdfdatasheet_russia/gt404a-b-v-g.pdf alternative will be to use AC176 i got my fingers on lately but i would prefer tu use the exotic stuff but as earlier mentioned the problem existed aswell with BC109C and other stuff from current production lines.

circuit and tutorial i used: http://beavisaudio.com/schematics/Dallas-fuzzface-npn-schematic.htm https://guitar.com/guides/diy-workshop/diy-workshop-build-your-own-fuzz-pedal/
other resouces: http://www.geofex.com/Article_Folders/fuzzface/fftech.htm http://diy.smallbearelec.com/HowTos/FuzzFaceFAQ/FFFAQ.htm http://diy-fever.com/effects/fuzz-face-revisited/

[GibsonGM]

YW...if you post your voltages at each collector, perhaps we can help. It should not be a hard thing to get them close, and to sound good.    I don't think you need a 100k!  A 10k pot in the collector of Q2 may let you dial in 4.5 - 5v, and you replace with a fixed resistor. Just by ear...that is how some do it, anyway!  I believe I needed to reduce Q1 collector R to about 18k to get it to cooperate...

Keep us posted...

[karsten_h]

assuming that i didn´t mess up that is the environment right now...

seexhb

[GibsonGM]

Does it still sound 'bad' when you listen to yourself play through it?   Making it sound good is all that matters      The 5.5 volts at collector of Q2 is very close.

If you want to make this so you can bias it, you must place a 10k trimmer where R3 is. It will be wired as a variable resistor.  https://sciencing.com/how-to-wire-a-variable-resistor-12176736.html

Many people first replace R1 with something like an 18K resistor.   The pot will be adjusted until you read about 4.5V on Q2 collector, but use your hearing as a guide for when it sounds right! 

[karsten_h]

thx alot! i replaced the R2 with the 10K trimpod and i am fiddling around with it and it´s pretty amazing to hear the sound change while adjusting the voltage, guess lower voltage for R1 (or transistor with lower gain) is useful because the lowest voltage i can adjust to is around 5,2V and it sounds better the closer i get to 5V:) so i am curious how it sounds below... what can be done about the HISSSSSSS sound? the whole circuit seems to be highly temp sensitive as foreseen with what i read about germaniums – but not experienced before. when i touch Q1 the voltage gets up pretty fast touching Q2 on the contrary seems to lower it but far more slow. whats still happening is that the fuzz only sets in when the guitar volume is turned up pretty close to max but in lower volumes the signal is still there now.

[GibsonGM]

Yes, leave the guitar all the way up...fuzz is supposed to clean up when you roll back volume. Hopefully some hiss goes away when you put it in its grounded enclosure, but high gain WILL make noise when you're not playing.    It sounds like you are getting close to a good bias point

To get < 5,2V, I think you do need to replace Q1 collector resistor with 18k.  You can also add a resistor in series with the trim pot to give you more range, perhaps 8.2K, or 10k, to allow you some more range of adjustment, before you change Q1 resistor.  You may not need to!   

[idy]

Fuzzes tend to be noisy, but your transistor(s) may be very leaky...that = noisy.

...you would have to test them....

http://www.geofex.com/article_folders/ffselect.htm

[karsten_h]

hi out there! i played around, biased and had some fun and learning by doing... thx to the amazing resources and people publishing and sharing their experience out there
added the fullermods as i had intended and as they are described here: http://www.geofex.com/Article_Folders/fuzzface/fftech.htm mod1 seems to lower the fuzz affect as described, did not get the use of it really, mod2 seems to destroy the made biasing - as intended i guess? turned the pot to half and biased it there correctly, the range seems to be around 3V - like this one when it goes to lower voltages and starts to clip
also added the stupidly wonderful tone control as described here: http://www.muzique.com/lab/swtc.htm, https://hammer.ampage.org/files/SWTC.gif and that one seems to work, like the use of it but it seems to interfere with the fullermod2? the bias voltage range gets pretty dense <1V so the mod practically does not exist no more - any idea to have those live together in the ecosystem?
what do you think of fiddling around with input/output capacitors and/or adding capacitors to the Q1/Q2 to soften things up? i am aswell curious what the addition of a diode between the Q1 base/collector circuit brings to the magic? as joe does in the badass distortion: https://tonefiend.com/tonefiend-diy-club-projects-resources/ expanding the circuit to an additional Q in front and make it bender like? part of me hates unlimited possibilities...
have a wonderful day!

[karsten_h]

Fuzzes tend to be noisy, but your transistor(s) may be very leaky...that = noisy.

...you would have to test them....

http://www.geofex.com/article_folders/ffselect.htm

will check on that for my transistors in stock and still shipping as soon as i have the needed resistors at hand during the next week or so... holidays coming

[karsten_h]

can you out there confirm what i wrote about the fullermods/tonecontrol interference? or didi i mess up something? what about using capacitors to seperate the circuits from one another?

[karsten_h]

i am aswell curious what the addition of a diode between the Q1 base/collector circuit brings to the magic? as joe does in the badass distortion: https://tonefiend.com/tonefiend-diy-club-projects-resources/ it is done in the bulk fuzz https://www.tonefiend.com//wp-content/uploads/DIY-Club-Project-2-v02.pdf part of me hates unlimited possibilities...
have a wonderful day!

[karsten_h]

tonight i checked the transistor leakges / gains from the germaniums and a couple of other i got... voltages, leakages and calculated gain are here:
...so the germaniums ARE leaking alot and ratio gain vs. leakage seems pretty bad for most except a couple, not surprising that much but what is confusing me is that the gains for the silicon ones differ ALOT from what datapages and my multitester say... i did the folowing calculations leakage=V2,4K*100, hFE real=(V2,2M-V2,4K)*100 my R1=2231K; R2=2,423K math again... hate that aswell