freestompboxes.org

Thanks to mirosol photos viewtopic.php?f=7&t=28913 and some others from the internet, I drew my first version of this schematic. Some values missing.

With regard to these both schematics:
https://robertkeeley.com/woo/wp-content ... -FUZZ1.png
https://i.pinimg.com/originals/e4/5e/41 ... 2e5789.jpg
is my guess for following Values:
R8 = 4.7 Kiloohms
C5 = 10 Microfarads
C6 = 47 Microfarads
R1 = 51 Ohms.

The schematic is right according the PCP trace, but there is something not right here.
The base of the AC128 has no DC connection, therefore the biasing cannot work.
A base potential divider or a base resistor connected to ground is missing on the PCB is missing.

Manfred, if you look at the photo, there is nothing else connect to base of the transistor.

It must be relying upon leakage to bias it.

Temperature stability will be an issue.

Chugs wrote:Temperature stability will be an issue.

Just call it mojo.

deltafred wrote:It must be relying upon leakage to bias it.

I see, an unusual ciruit, so that I trial is needed to find out the truth.

I ran a trail of a reduced circuit today.
I applied the collector and emitter resistor of the EQD Crimson Drive schematic.
I was really very surprised, the circuits works indeed without base resistor.
The input signal level varied from 100 Millivolts to 1 Volt RMS.
The clipping started at a input level of about 300 Millivolts.

I made a further trial adding the bypass capacitor.
The clipping started at much lower input levels.
Unfortunately, 70 Millivolts is the lowest output level of the integrated oscillator in my digital oscilloscop.