Fuzz output issues

[soma89]

So i REALLY need some pointers rn.

I finished a pedal using this schematic and the pedal has VERY LOW output. Bypass signal is fine.

Ive checked things over a dozen times, tried different input caps and still....extremely low output. Some would say no output but you can hear a faint fuzz signal when activated. I have a stash of 2n2222a's.


**The only thing ive done different was i used a 1.8M resistor instead of the 2.2M.

Also, instead of the 0.0039uf cap i used a 0.0033uf (3.3nf)

The batteries cold on the diagram is confusing me, can i just send it to ground?

Ive tried the pedal in the enclosure and out..same results.

[Plexi]

Did you tried to go straight from the diodes to out volume pot?
I really don't understand how works that tone stack

[soma89]

Hey thanks for your input!

Plugged straight into the diodes i get a LITTLE more signal. Its still low though!

When i touch the bottom of the transistor socket of the collector on Q2 the volume spikes up along with a whole bunch of hum.

I might try to solder the tranny straight to thw board

[soma89]

K so i soldered straight to the board and same deal. The collector of q2 spikes up to regular volume when i touch the node!

What does this mean??

[antonis]

That means you push Collector to almost ground (negative maximum swing) and it points out bad biasing..

Try to by-pass diode pair to see if you have enough volume..

[duck_arse]

I rekon you want to add a blocking cap between the transistor collector and the two diodes, maybe allow the collector a little swing. try 100nF, report back. watch out for the volume, tho.

the battery cold on the diagram seems to indicate the battery black lead goes to the "ring" of a stereo socket, so when you plug-in a mono plug, it shorts the ring to the sleeve, allowing the ground connection, battery current flows, notes pour forth, everyone is happy. if you don't use battery, you can just connect all your grounds to a common line/point.

[antonis]

And perhaps a current limiting resistor just after Stephen's cap proposal to avoid Collector overloading...
(as it is, diodes are set in parallel with Collector resistor, over-dominating it..)

[soma89]

Ok so thanks for all the help. I noticed that the signal was not passing through the diodes properly. Volume is now OK.

Now the signal sounds starved. Very glitchy, choppy, and oscillating.

Ive checked and double checked the battery 9v input. Gonna check voltages..

[antonis]

Step 1. Try to reduce Q2 out current..
(placing a resistor in series with diode pair raises Q2 swinging headroom - which now is less than 600mV, depending on V_CEsat..)

Step 2. Place a 47-100pF cap in parallel with each 2M2 resistor..
(it prevents from high frequency oscillating/squealing..)

[soma89]

I should probably clear something up.. My circuit has 2 grounds n opposite ends of the board jumpered together.

Im thinking theres a ground loop issue causing oscillation through the transistors?

[Barracuda]

Oscillation can be caused by bad grounding from jacks, check you've got your lugs wired up the right way round! Also this pedal looks like it would have low output after the fuzz section you have diode clipping which will squash the signal and then to further attenuate the volume is the tone stack. I cant imagine it would be much louder than your unity guitar signal depending what setup you have, but thats not to say the fuzz isnt useable, depending on when you want to use it and what pedals you have around it (if on a pedal board). If you fix your problems and find its too quiet still try add a boost somewhere after the fuzz section (before or after tone stack, diode clipping is your preference). Or just do that the next time you have that problem if youre happy with the build . And the low value caps from collector to base on the trannies is a good shout for oscillation! Either that or a big fat ass cap like 47uf or more from 9v to ground will help filter your power.
Hope I could help!

[MaxPower]

For  what it's worth. I breadboarded this circuit up to the  diodes and it worked. Removed the diodes and the volume increased. Didn't notice much difference in the sound without the diodes other than the volume  increase.

[duck_arse]

looking again at that circuit - I'm calling it "wrong". there needs to be a blocking cap off the collector to whatever follows. at the moment, there will be DC at the output jack.