Need schematic reviewed

[NotaguitarHero]

Hi all,
I built a simple fuzz pedal with two MSPa18 transistors and it was very boring. I started tinkering and I ended up with a kick ass overdrive sound. I added a few capacitors etc. but now I'm worried that the transistors are being pushed beyond their limit. I'm not familiar with calculating the load on these transistors,  and honestly I'm not even sure why the pedal sounds so much better at this point.  If someone wants to take a look at my schematic and let me know what they think I would greatly appreciate it!
Let me know and I'll post the drawing

[PRR]

Welcome.

> I'm worried that the transistors are being pushed beyond their limit.

Are they smoking? Even hot?

If they blow up, will anybody be injured?

Considering the price of MPSA18, I would not put a lot of thought into it.

"Overdrive" is all about exceeding the *circuit's* limits. Unless you have some radically small total resistance, it is unlikely a fuzz should burn transistors; if it does, it probably already has (they burn quick).

[marcelomd]

the transistors are being pushed beyond their limit.

That's the general idea of overdrive/distortion/fuzz.

Also, welcome!

[Rob Strand]

Just measure the supply current.  That will give you an idea.

[sixthfloor]

Let me know and I'll post the drawing

Hi, I'd like to see the schematic if you don't mind. I don't know much about fuzzes and transistor-based ODs, but I'm interested in checking this out 

[antonis]

I'd like to see the schematic if you don't mind.

+1..

Welcome, of course.. 

[duck_arse]

I'd welcome a sight of the circuit dia, and welcome.

[iainpunk]

Welcome to the forum!
I'd love to see the circuit! Am always curious about overdrive and fuzz schematics which are not standard. Especially if the od is made out of a fuzz schematic!

[NotaguitarHero]

Ok, I will post ASAP. Sorry for the delayed response.

[NotaguitarHero]

I am new to building circuits, and after I drew this out I realized it is similar to a fuzz circuit. Today I too some voltage readings as you can see in small numbers. It definitely sounds hotter than what I would consider "fuzz" but then again, maybe I haven't heard a good fuzz pedal?
Anyway, here it is
Thanks guys
Transistors are MSPA18's

[PRR]

It's related to "Fuzz Face", which is just a high-gain "clean preamp" pushed way further than "clean".

The 0.01uFd from middle to front cuts highs going in, but different for every source.

A FF usually has the output cut-down (like 6.8k and 680r?) because a full 9V swing would faint most guitar amp inputs. You get a similar effect, plus some treble loss, with your output network 0.01u 30k 0.02u.

Nice to mark transistor symbols with an Emitter arrow, but what you wired is clear by the voltages.

Nothing is gonna explode. Q2 has 0.3mA 1.2mW and is surely a 100mA 300mW part. Q1 even less stress.

[sixthfloor]

Anyway, here it is

Thanks ! Also thanks to PRR for the explanations, much appreciated.

I've breadboarded the circuit, and to my ears it definitely sounds like a fuzz - that square wave sound. I've heard hotter fuzzes, but what I like in this one is that it goes pretty well before the couple of distortion pedals I put behind.

[Elektrojänis]

The 7,9V measurements on the upper legs of the 30k and 10k resistors suggest that your battery might be quite worn/old. Sometimes that makes some fuzz-circuits sound better. You should just be aware that it might not sound as good with a new battery.