Newbie question... (Only the initial attack is heard)

[eddie83]

Hey guys,
pardon me, this's my first project, got a qn about grounding for the fuzz face. Where do i connect all the ground pts to?
http://www.generalguitargadgets.com/diagrams/fuzzface_sc_pn.gif
Do i just connect all the ground points together and leave them alone? Or do i connect the ground points to the negative polarity of the 9v batt? Pls advise, many thanks in advance....

Ed

[petemoore]

You'll have to say Pnp or PNP
 That would be either the Pos ground [I like these ones for the GE FF's, using PNP transistors you have a matched set or some coming?].

 Otherwise I use NPN Neg ground and Si transistors of NPN type.
 This way all points marked ground including battery negative go to circtuit ground, on the board.
 All points must read ground including jacks, volume pot.

[eddie83]

Thx for the prompt reply, petemoore. yes, i do hav a matched pnp Ge transistors, got them from small bear elec.

I don't really understand u when u mentioned
"This way all points marked ground including battery negative go to circuit ground, on the board. "

So do u mean connecting all points marked ground to the box chasis, including the battery negative?

regards,
Ed

[petemoore]

PNP...
 Were working with a Pos Ground FF circuit.
 ""THe Battery POS>
 all points marked ground""
 Get connected together.
 All polarized caps must have the negative lead going to the most negative side of where they're hooked up...
 Heres what I do...use all nonpolar caps [non elecrolytic types like film cap greenies or whatever] excpet the bypass cap, be certain the + of the polarized cap goes to ground for PNP operation.
 For a more illustrated, and better expl. check out Fuzz Central, or GGG, and compare the PNP Pos Gnd    and     NPN Neg Gnd FF schematics. Notice the battery and polarized caps are inverted from Pos to Neg setup.
 If you use metal jacks and box, connecting Gnd. to one of the jacks only... you should be able to verify with DMM beep that Gnd goes to both jacks and box. The jack you connected SHould connect also the box and the other jack to ground, saving the trouble...Just hook black DMM to a known ground and test all other ground points from there in beep mode setting.

[KORGULL]

Do i just connect all the ground points together and leave them alone? Or do i connect the ground points to the negative polarity of the 9v
batt? Pls advise,

Connect all the ground points together on the board (except battery). Connect battery + (PNP circuit only) to the input jack ring lug. The jack's sleeve gets wired to the board ground point - when you insert instrument plug it will connect ring to sleeve completing the circuit - connecting battery to board .
//www.generalguitargadgets.com/diagrams/switch_lo_battery.gif
As pete mentioned, remember to reverse the polarity on all polarised components - so ground is + because it is a PNP pos. ground circuit.
Good Luck.

[eddie83]

argh, i've tried it the fourth time on my bread board, no sound still, juz buzzing noises... Any suggestions on how to do prototypin on the breadboard properly? I'm almost giving up with the fuzz box.....

[KORGULL]

Hard to say what the problem is - many possibilities.
How are you hooking up the in/out jacks and pots to the board?
If there isn't a solid connection because the wires are just twisted onto the lugs you will have problems.
Keep checking all connections. There is probably a simple mistake somewhere. It is easy to stick a lead in the wrong row of holes and not notice it.
Make sure transistor orientation is correct.
Check polarity of caps/battery.
Just some quick thoughts - don't know what else to tell you.

Search around for a how-to article on breadboards if you aren't sure you are using it properly.
Good luck.

[eddie83]

Thx everyone, i've finally got the fuzz face working... it's was a stupid error. soldered the output wire to the sleeve instead of the tip, thus the buzzing sound... There wasn't much sustain cos it's was built on the bread board, will transfer it to strip board and get it into my efx box.  
A million thanks to petemoore and KORGULL, u guys made my first stompbox a successful one!!!

[KORGULL]

Good to hear you got it working. The first box is definitely the hardest.
Even though it sucks when things don't work correctly right away - I usually learn more while debugging a non-functional circuit than I would have if there were no problems.
That said, It is nice when things work first try once in awhile too :wink:

[eddie83]

Hey ppl,

i need help again, my fuzz face isn't working correctly, it seems like it cuts off the lower volume sounds, which means my guitar sounds very very staccato on the effects, only the initial attack is heard... any idea anyone? is there anything to do with resistors? or could it be the i have flipped the emitter/collector leads on either of the Ge transistors? pls advice, thx everyone....

[bwanasonic]

it seems like it cuts off the lower volume sounds, which means my guitar sounds very very staccato on the effects, only the initial attack is heard... any idea anyone?

This is often called "gating" and is most likely from mis-biased transistors. Do you have a Multi Meter to take voltages at the pins of the transistors? If you could post those, it might help troubleshooting. I would also mention that a lot of people (including myself) have had problems with getting a PNP/NEG ground version of the Fuzz Face to work. My stock advice is to stick with positive ground versions and skip the convenience of a DC jack. The Fuzz Face draws very little current, and batteries last a REALLY long time.

Kerry M

[KORGULL]

Hi, I didn't realize you were building PNP negative ground pedal. I didn't check the link in your first post  :oops: - only went by what you and pete had posted - didn't get all the info or I wouldn't have stressed the fact of reversing polarities.
Anyway, did you check the debugging pages here and at Geofex yet? Maybe something there can help.
Here's a link that may or may not help://www.geofex.com/fxdebug/bias_prob.htm
You could always try breadboarding it again but using positive ground setup and see what happens.

[aron]

Yes it's most likely a biasing problem. Measure the collector voltage (from ground) and and it should be approx. half of the battery voltage. -4.5V etc...

[jmusser]

One thing to check right off the bat is your resistor values. Because of bad light or whatever, you could have put in for example, a 2.2K instead of a 22K. If the 3rd band is thin, then sometimes it'll look red instead of orange. That will cause misbiasing, because I've done just that. Also make sure that one solder joint on a cap leg is not now touching the other. If something is working, and then all at once it's not, you could have pulled on a wire and moved a lead of one component into the other. If you get a "splat" sound when you hit the guitar strings, then the transistor biasing voltages are off. Again, I know that because I've done it.

[eddie83]

firstly, merry christmas and thanks everyone, u guys hav been very helpful.
I've changed to the PNP / +ve ground circuit, the gating has reduced but it's still there.

I've tried checking the resistors, all the values are correct, however, i substituted the 20μf capacitor with a 22μf, hope that's not the problem? The other thing might be because i hav been soldering and unsoldering the Ge transistors, not sure if they have been damaged, don't think so though... I got the Ge transistors from Small Bear, quite sure that he matched it for me.

Will difference in temperature cause a matched Ge transistor pair to change their characteristics, for eg.  resulting in the gating of signals? It's because i'm living in Singapore, the weather here's much higher than that of US, where the transistors were matched...

[KORGULL]

I know that germanium transistors can be easily damaged by excessive soldering iron heat. You should try to use sockets for these transistors.
I am guessing that if a transistor was damaged, the resulting problems might be more severe than just  minor gating. So the transistors may not be the problem. Don't take my word for it though - I haven't had alot experience with bad transistors and all their symptoms.

I would mess around with different resistor values, or use potentiometers - (trimmer or regular) in place of resistors to fine tune the circuit until it sounds good then disconnect and measure the resistance setting on each pot and replace with a regular resistor of that value. Were the resistor values (used in testing the transistors)sent to you with the transistors? If so, try those values instead of the ones in the schematic.

Will difference in temperature cause a matched Ge transistor pair to change their characteristics, for eg. resulting in the gating of signals?

I did read an article about testing germanium transistors that said you should wear gloves and use tweezers to handle them because they are so temperature sensitive that the heat from your hands can influence the meter readings. I hear people claim that their Ge based pedals sound different on cold mornings as opposed to warm afternoons also.
bwanasonic wrote:

Do you have a Multi Meter to take voltages at the pins of the transistors? If you could post those, it might help troubleshooting.

Maybe if you did this somebody more experienced than me can tell you exactly what is happening. I am mostly just remembering some things I've read - I haven't actually had to fix a mis-biased circuit (yet).
To measure the voltages just set your meter to read DC volts, power up the circuit,  put the black probe to ground and with the red probe touch each transistor leg. List the results for each transistor's E,C,B.
Good luck, -hope you only need some minor resistor changes and not a transistor replacement.

[petemoore]

Check the bias of the Pos Gnd PNP FF on Q2's collector [for starts], often this reading will show if there's a bias problem.
 I always use sockets or heat sinks [on the trannsistor leads when soldering].
 Also I test a PNP ff circuit with cheep 2n3906's initially, then, when it seems to be working somewhat, install the Ge's.

[eddie83]

Okay guys, i've got the voltage recorded, Q2's collector output's really weird:

Q1: E/0v      C/-0.25v   B/-0.06v
Q2: E/-0.1v   C/-0.11v   B/-0.25v

tat's what i got from measuring my circuit with a sanwa analog multimeter, think will get a DVM soon... I'm really wondering what's causing the Q2's collector output to be -0.11v,  tot it should be nearer to-4.5... pls advice, thx everyone for your attention... happy new year!