FuzzFace battery problems

[Urban Osterman]

Hi all
I have just put together a FuzzFace with negative ground and
PNP germanium tranistors..
It works fine when running it from my 9V power supply.
but does not work when using a 9V battery...?
it goes TubbTubbTubbTubb....?

Does anyone have any clue...

/Urban

[petemoore]

Can you post the measured voltage of the battery used?

[bwanasonic]

Hi all
I have just put together a FuzzFace with negative ground and
PNP germanium tranistors..
It works fine when running it from my 9V power supply.
but does not work when using a 9V battery...?
it goes TubbTubbTubbTubb....?

There was a recent poster with the same problem. If you do a search here, you will find that a PNP/neg. ground Fuzz Face is problematic for many builders. In theory it should work, but judging from posts here, it doesn't more often than it does. I had the same *motorboating* problem when I tried it. I just switched over to pos. ground (no adapter), and have been happy since. Batteries last forever in it, so I don't miss the adapter. Search the archives on this though.

Kerry M

[Urban Osterman]

Can you post the measured voltage of the battery used?

Hi Pete
Yes it is a bit funny as it looks OK when measuring Voltage..
I measured with both 9Vpower supply and a 9Vbattey.

With 9v Power Supply(actually 9,09V)

on Q1 emitter       9,09V
on Q1 collector/R2  8,39V

on Q2 emitter       8,51V
on Q2 collector/R5  2,27V


With Battery supply (actually 9,25V)

on Q1 emitter       9,25V
on Q1 collector/R2  8,49V

on Q2 emitter       8,66V
on Q2 collector/R5  2,45V


/Urban

[petemoore]

Can you post the measured voltage of the battery used?

Hi Pete
Yes it is a bit funny as it looks OK when measuring Voltage..
I measured with both 9Vpower supply and a 9Vbattey.

With 9v Power Supply(actually 9,09V)
 >>>The recommendation for POS GND FF, when using PNP Ge;s is one I second. Much less Problematic.
on Q1 emitter       9,09V
on Q1 collector/R2  8,39V
 This transistor is not working, Q1 emitter needs to connect to ground. IIRC the Q1 collectors are like around less than 2v....low Voltage there, get that emitter at ground and the other V's'll change too.
 

on Q2 emitter       8,51V
on Q2 collector/R5  2,27V
  Are you sure you're not typo'ing? Collector should be near 1/2 supply voltage, higher potential there than the Base or emitter.
 

With Battery supply (actually 9,25V)

on Q1 emitter       9,25V
on Q1 collector/R2  8,49V

on Q2 emitter       8,66V
on Q2 collector/R5  2,45V


/Urban

I think there's a wiring error or something else going on, but I'd still [II were my FF] convert to Neg Gnd. Just swap polarity of PS and any polarized caps [probably just the 22uf emitter bypass cap] to change pos to neg gnd. I like to pretest ccts. with 2n3906 till it starts amplifying, to insure Ge safety.

[Paul Marossy]

The problem that the other poster had was due to the battery type. His circuit didn't like anything but alkaline batteries...

[Urban Osterman]

The problem that the other poster had was due to the battery type. His circuit didn't like anything but alkaline batteries...

Hi
Thanks for your reply...
Yes I did a search for 'FuzzFace' and found the discussion from around sept 2003, about the battery type.

But someone also said that there was a solution about..
inserting a 16K resistor to the Q1 Base
and a few more sugestions..

I'll try that tomorrow
and I will post my findings here

Again
Thanks for your time ...

/Urban

[Urban Osterman]

Can you post the measured voltage of the battery used?

Hi Pete
Yes it is a bit funny as it looks OK when measuring Voltage..
I measured with both 9Vpower supply and a 9Vbattey.

With 9v Power Supply(actually 9,09V)
 >>>The recommendation for POS GND FF, when using PNP Ge;s is one I second. Much less Problematic.
on Q1 emitter       9,09V
on Q1 collector/R2  8,39V
 This transistor is not working, Q1 emitter needs to connect to ground. IIRC the Q1 collectors are like around less than 2v....low Voltage there, get that emitter at ground and the other V's'll change too.
 

on Q2 emitter       8,51V
on Q2 collector/R5  2,27V
  Are you sure you're not typo'ing? Collector should be near 1/2 supply voltage, higher potential there than the Base or emitter.
 

With Battery supply (actually 9,25V)

on Q1 emitter       9,25V
on Q1 collector/R2  8,49V

on Q2 emitter       8,66V
on Q2 collector/R5  2,45V


/Urban

I think there's a wiring error or something else going on, but I'd still [II were my FF] convert to Neg Gnd. Just swap polarity of PS and any polarized caps [probably just the 22uf emitter bypass cap] to change pos to neg gnd. I like to pretest ccts. with 2n3906 till it starts amplifying, to insure Ge safety.

Hi Pete
Thanks for your reply

I do have a negative ground PNP FuzzFace...
So according to some entries in this forum
its ok when its about less-than-1-volt difference
between Q1 collector and emmitter, when the emitter is at +9V

And its not a typo for my 2.27V at Q2 Collector...

It's mainly because I got my selected GE transistors from Small Bear.
They also have a suggested value for R5,
which for this transistor is 3,9 K
instead of the 8,2K in the original schema.
(Q2 gain is about 154)

(I actually changed this resistor to see what I got.
And yes, I got about 4,5V at Q2 collector
with the 8,2K resistor, instead of the 3,9K.
I also got some lower output-volume from the FF,
and it sounded about the same.....)

So, to me, it not so big difference,
as the 'voltage-swing' that Q2 can have
is about 2V more, with the 3,9K value
than the 8,9K ohms,
giving the higher output-volume.

But it still don't work with my battery

I also inserted a 15K resistor (didnt have a 16K)
in series with the Q1 Base, as someone suggested here,
but still not working with battry.

Someone suggested an Alcaline Battery
So I'll go out today and get me one, and try.

Thanks again for your time in this problem... :-)

I'll get back here with my 'alcaline-result'

Have a good day
/Urban

[Paul Perry (Frostwave)]

Try a large electrolytic cap across the battery.
Motorboating is a classic sign of the power supply impedance being too high.

[Paul Marossy]

Motorboating is a classic sign of the power supply impedance being too high.

Hmm... I did not know that. That cap across the power supply trick is something that is getting filed in my mental Rolodex right now.  :wink:

[Urban Osterman]

Try a large electrolytic cap across the battery.
Motorboating is a classic sign of the power supply impedance being too high.

Hi Paul
Thanks for your reply

I had a 10uF cap accross the battery...
and inserted a 220uF/25V instead and it now made an improvement...
about halvway up the 'fuzz-controll pot' the motorboating started...

the lower half of the 'fuzz-controll' sounded ok now (=lesser fuzz)
but only the upper half had this motoring = (more fuzz).

I then I changed to an ALCALINE battery
and motoring now dissapeared...  

So it seemes that this could be further trimmed
maybe even a biggar cap or some diod

I'll try some more...
/Urban