Enclosure not stated · 2 knobs
Hornby Skewes Zonk Machine (Jonaz version)
Based on the Hornby Skewes Zonk Machine· 4 other boards clone it
- Category
- Fuzz
- Controls
- Fuzz · Swell
- Price
- see vendor
- Also as
- Vero layout · from Revolution Deux
- Tags
- freestompboxes.org trace
From the vendor
Another Zonk Machine version, traced from an original unit pointed out by Jonaz. Same three-transistor germanium structure as the Tone Bender MKI, with a 33K resistor under the Fuzz pot divider and a 47n output cap.
The tracer measured gains of 70, 116 and 97 for Q1-Q3 and suggests socketing the transistors. The Zonk is very bright: try input caps between 1n and 10n, perhaps on a three-way switch. Use a log/audio-taper Fuzz pot; a linear one limits the useful range. It mostly sets the bias of Q2. An SPST switch across the 2.2M output resistor gives a much louder, nastier sound.
Schematic
The schematic is in the post. Open it at Revolution Deux. No KiCad fragment has been drawn for this circuit yet.
Parts list 19 rows
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| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 10 | ||||
| R1 | 1M | 1M | read from the schematic by eye | |
| R2 | 4.7K | 4.7k | Q1 emitter; read from the schematic by eye | |
| R3 | 470K | 470k | read from the schematic by eye | |
| R4 | 2.2K | 2.2k | read from the schematic by eye | |
| R5 | 33K | 33k | read from the schematic by eye | |
| R6 | 3.3K | 3.3k | Q2 collector; read from the schematic by eye | |
| R7 | 15K | 15k | read from the schematic by eye | |
| R8 | 10K | 10k | Q3 collector; read from the schematic by eye | |
| R9 | 56K | 56k | read from the schematic by eye | |
| R10 | 2.2M | 2.2M | read from the schematic by eye | |
| Capacitors 4 | ||||
| C1 | 1n | 1n | input; read from the schematic by eye | |
| C2 | 25u | 25u | electrolytic; read from the schematic by eye | |
| C3 | 100n | 100n | read from the schematic by eye | |
| C4 | 47n | 47n | output; read from the schematic by eye | |
| Transistors 3 | ||||
| Q1 | A02650 | A02650 | germanium PNP; read from the schematic by eye | |
| Q2 | OC75 | OC75 | germanium PNP; read from the schematic by eye | |
| Q3 | OC44 | OC44 | germanium PNP; read from the schematic by eye | |
| Potentiometers 2 | ||||
| Fuzz | A50K | A50k | Potentiometer | read from the schematic by eye |
| Swell | A500K | A500k | Potentiometer | read from the schematic by eye |
Other boards based on the Hornby Skewes Zonk Machine
- Hornby Skewes Zonk Machine Effects Layouts (blog)
- Hornby Skewes Zonk Machine Revolution Deux
- Hornby Skewes Zonk Machine (alternate version) Revolution Deux
- Hornby Skewes Zonk Machine turretboard.org