Can I build a basic fuzz circuit with these components?

[louloomis]

Hey All.

Totally new to pedal building here. Apologies if this question is the equivalent of "can I build a car engine out of tofu". But maybe someone can help?

I have a few electronic components and I am trying to build a very, very basic fuzz circuit, similar to a Bazz Fuss. I have the output jacks and battery connector already. I don't care if the circuit sounds bad, I just want to get my feet wet with building my first pedal.

Here are the components I have The number in parenthesis is the number of units I have of each:

CAPACITORS (GREEN SQUARES):
68 nanofarad (1)
100 uf (2)
.22 uf (1)

CAPACITORS (BLUE CYLINDERS):
47 uf (2)
1 uf (4)
.22 uf (1)

CAPACITORS (PINK SQUARES)
.1 uf (3)

TRANSISTORS:
BC415B (1)
BD911 (1) - these appear to be inappropriate since they seem to be for power circuits?
BD912 (1) - these appear to be inappropriate since they seem to be for power circuits?

DIODES:
1N4002 (2)
LED looking ones - don't know anything about them (2)

RESISTORS:
220 OHMS (1)
10K (1)
100k (1)

Can I make a fuzz circuit out of all of this? Thanks in advance.

Regards,
LL

[imJonWain]

Possibly, not ideal, but try it and see!  You have the "right types" of stuff to build a bazz fuzz version. 

[louloomis]

Thanks for the response. I am looking for more specific feedback. For example:

Do you know if any of these transistors are serviceable for a fuzz circuit?

I'm asking because I have researched them online and do not see them discussed anywhere as being used for this purpose.

LL

[idy]

What the other guy said... google "bazz fuzz." It is a simple one transistor one diode fuzz. the 415B would do this.

[antonis]

I don't care if the circuit sounds bad, I just want to get my feet wet with building my first pedal.

Junk box fuzz..??
(funny enough..)



If you could find a 1-10nF for C it would save you 5 solder joints..

[Banjan73]

(P.S)
Those blue sylinder caps are probably electrolytic ones. They need to be connected the right way to work, since they + / - polarity.
Antonis: sure that input cap is connected correctly?

[antonis]

Antonis: sure that input cap is connected correctly?

Pretty sure, I could say..
(unless there is a higher than 9.2VDC on Input - for 8.2V roughly estimated Base voltage plus 1V reverse polarity safe "withstand" ability..)

[louloomis]

Thanks everyone....Antonis, etc.!

This is really helpful and interesting info. Let me work on this based on your schematic.

Will let you know how it turns out.

Great stuff!

LL

[Marcos - Munky]

I think you can use just the 68nF or a 100nF cap instead of that series cap association with no problems at all. I mean, it'll change the sound a bit, but as you stated, it's just an experiment for you to get started.

I'd suggest you to try the bazz fuss, is simple enough and will work with almost everything you already have. I mean almost everything because the BC415B is a pnp transistor, while you need a npn transistor for the bazz fuss. But probably the BD911 will work. Anyway, a general purpose npn transistor is way cheap to buy, and very easy to salvage on old boards.

[iainpunk]

not going to add anything to the convo but what happened  to "welcome to the forum"?

also, Welcome to the forum!!!

cheers,
Iain

[swamphorn]

Playing off of antonis' Junk Box Fuzz, I would try

• moving the clipping diodes to the output like an Electra;
• using a 220 nF capacitor on the input; and
• bypassing the 220 Ω resistor with a 1 μF capacitor.

This would give you a fuzz with a steep bass cut and reasonably high gain.

[antonis]

Also good approach, swamphorn..

Although, with 100nF input cap and Emitter bypassed resistor, input HPF cut-off frequency is set to ultrasonic Hz..
( effective input impedance should be lower enough than 100R )

[swamphorn]

Also good approach, swamphorn..

Although, with 100nF input cap and Emitter bypassed resistor, input HPF cut-off frequency is set to ultrasonic Hz..
( effective input impedance should be lower enough than 100R )

I'm not so sure about that. I did a quick simulation of the bias conditions; with β = 330 (the typical value for a BC415B), I_C = 0.8 mA, so r_π = (β + 1) 26 mV / 0.8 mA = 11 kΩ.

[antonis]

Although I'm not able for the moment for simulation, I'll take your word for that..
But what's grouned Emitter stage gain..??
'Cause, 100k feedback resistor should be divided with stage gain + 1 and set in parallel with r_π..

[swamphorn]

Although I'm not able for the moment for simulation, I'll take your word for that..
But what's grouned Emitter stage gain..??
'Cause, 100k feedback resistor should be divided with stage gain + 1 and set in parallel with r_π..

With the same values as before, the open-loop gain is approximately
A_V = - R_C / r_e
= - 10 kΩ / 33 Ω
= - 308
so by the Miller effect the feedback resistor has an effective impedance of 100 kΩ / (1 + 308) = 324 Ω. Pretty terrible for anything but a fuzz or a treble booster if you ask me. This won't be reduced much by the base impedance resulting in a cutoff frequency of about 2200 Hz. Note, however, that the amplifier only reaches its maximum gain at the corner frequency of the collector resistor and capacitor, 720 Hz which would change the final response. All in all, the cutoff frequencies are bound to interact in very interesting ways and I'd have to simulate the frequency response to be sure.

EDIT:
And here is the frequency response as simulated with the traditional 10 kΩ source impedance.

[antonis]

I presume OP should be ready to ask for mercy, by now..