TIP29 fuzz

[Gus]

Med power transistor fuzz goodness
VDCM is what was measured in circuit with the TIP29 build other voltages are from the sim using 2N3055s.
Betas measured with a LCR transistor diode etc. meter

Built it sounds very good no gating

[Kipper4]

I bet that has some headroom.
Why not take the output from the collector of Q2 IE below R2 ?
What sort of hfe does that jelly bean have please?
Possible tone shaping with C1?
Sorry for the daft question.

[Gus]

Betas are in the screen shot 123,143 measured with one of the atmega based meters
The 2K and 330 are the output voltage divider if you take it off the Q2 collector it will be too high in level
It is interesting what happens when you change the value of the Q2 emitter cap.  100uf seems to give more IM distortion
The med power devices have a larger die area and can have more capacitance
Drilled a box and waiting for the paint to dry
This one might be fun with a bass
The web based 4.5VDC at Q2 needs to be corrected. The correct voltage is what you design for sometimes you want 4.5VDC other times you don't.

Next step might be a gain stage before this like a MK2

[Kipper4]

Thanks Gus I'm not used to reading sims so I didn't guess that was the hfe hopefully n future I'll remember.
Thanks for explaining.

[mac]

I like three things about power transistors,
They have high internal capacitance and low hfe like some germs,
And gain fall faster with low base current than general purpose transistors, ie, 2n2222, mpsa42, etc.
That means a better clean up with the guitar volume.

mac

[duck_arse]

hey gus, how come Q1, with grounded emitter, is only 250mV at the base?

[Gus]

250mV is from the sim. After I put it together(the paint should be dry today) I will measure the real base to ground voltage.
Real voltages with two TP29 are the ones with VDCM at the end

[Cozybuilder]

I'm impressed Gus- breadboarded, mine has very good tone, sustains forever, cleans up well with the guitar vol. A couple of component subs:
Q1= 2N3055, Q2= TIP31c
Q2C: 560R + 1K8
Vol: A100K
All other component values as per screen shot

       E           B         C
Q1   0V       0.51V   1.75V
Q2  1.19V    1.75V   6.37V
Source: 9.09V

[Gus]

Mac's post is short and to the point explaining the goodness of the power transistor
Cozybuilder thanks for the feedback

Something a little different. Power mosfets are fun.

[deadastronaut]

funny i just pulled apart an old sound to light project

reclaimed 2x tip31's from it... cheers Gus. 

[mac]

Try bd237, hfe: 70-150, high internal capacitance.

About €1,00 @ Mouser Spain.

mac

[Cozybuilder]

One knob, two transistors? Shoot, this sounded like it should fit in a 1590LB. It does.

2N3055 Q1, TIP31c Q2, BS170 Millennium Bypass, Wima 1uF poly out, short Panasonic 100uF 16V electros; trimmed jacks & transistors, ⅝" standoffs with 2-56 screws; and a bit of head scratching to make it all fit. (& yes, it was worth it)

Cheers and thanks to Gus for another interesting, great sounding design

[deadastronaut]

excellent build russ......

[Gus]

I like how the 2N3055 was trimmed to fit

I like the name.

[bluebunny]

 

Just    ...

[rutabaga bob]

Nice!

[duck_arse]

I see it ..... but I don't believe it, except he's done it again. therapy, russ?

[Cozybuilder]

Ahhh, but this IS therapy     

I can't believe no one gave their version of the acronym B.A.P.T. 

[duck_arse]

does it have to do with arse size and power transistors?

[Cozybuilder]

does it have to do with arse size and power transistors?

It does