Enclosure not stated · 5 knobs
Fuzzhead Fx Harmonic GyrolatorVerified
Based on the Fuzzhead Fx Harmonic Gyrolator
From the post
Harmonic Percolator is one the coolest vintage dirtboxes out there with its simple yet unique design, its odd even order harmonics texture, odd mojo parts and it is also a very good overdrive with the gain control rolled back. But using mostly humbucker equipped guitars nowadays it tend to be overly compressed and a bit muddy and dull. Started to tinker with it tso it would suit hot humbuckers but no dice. As it is an unique circuit like no other, the usual mods didn't work out very well like reducing input cap or add a resistor in line with the input signal. But I stumpled upon Dead End Fx Splinter project whcih offers a sollution for this namely reducing the coupling cap value between the transistors and adding a cap across the base of Q1 and ground. Later on I added a "Texture" control which techically is a resostat which alters the resistanse to ground for one of the clipping diodes. Most stock HP's has 4,7k resistor here for some assymetric clipping. I used a 10k pot so stock setting is at noon, turn it up and you get a more open and wide distortion, roll it back for some glithy compreesed sounds with sub octaves jumping around. And I added a two band gyrator tonestack at the end with values not to far away from Boss HM2. The result is a quite lo-fi, fat, industrial and grim fuzz.
Schematic
This is a board layout, a drawing of where each part goes, and the post may link the schematic it was drawn from. Open the layout at Dirtbox Layouts. No KiCad fragment has been drawn for this circuit yet.
Parts list 38 rows
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Check before you build · 2 values the reader of this layout was not sure of
- 91K at column 15, rows C-F: printed clearly, unusual value
- D1-D3: legend says only 'Germanium', no part number
| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 14 | ||||
| ×1 | 10Ω | 10 | read from the layout by eye | |
| ×1 | 330Ω | 330 | read from the layout by eye | |
| ×1 | 470Ω | 470 | read from the layout by eye | |
| ×1 | 3.3K | 3.3k | read from the layout by eye | |
| ×2 | 10K | 10k | read from the layout by eye | |
| ×2 | 18K | 18k | read from the layout by eye | |
| ×2 | 47K | 47k | read from the layout by eye | |
| ×1 | 51K | 51k | read from the layout by eye | |
| ×1 | 91K | 91k | read from the layout by eye | |
| ×1 | 100K | 100k | read from the layout by eye | |
| ×1 | 220K | 220k | read from the layout by eye | |
| ×1 | 1M | 1M | read from the layout by eye | |
| ×1 | 1.2M | 1.2M | read from the layout by eye | |
| ×1 | ? | ? | LED resistor, value not given; read from the layout by eye | |
| Capacitors 13 | ||||
| ×1 | 100pF | 100p | read from the layout by eye | |
| ×1 | 470pF | 470p | read from the layout by eye | |
| ×1 | 5.6nF | 5.6n | read from the layout by eye | |
| ×2 | 18nF | 18n | legend: increase to 47nF for single coils; read from the layout by eye | |
| ×1 | 47nF | 47n | read from the layout by eye | |
| ×1 | 68nF | 68n | read from the layout by eye | |
| ×2 | 100nF | 100n | read from the layout by eye | |
| ×1 | 120nF | 120n | read from the layout by eye | |
| ×1 | 1uF | 1u | film; read from the layout by eye | |
| ×1 | 1uF | 1u | electrolytic; read from the layout by eye | |
| ×2 | 4.7uF | 4.7u | electrolytic; read from the layout by eye | |
| ×1 | 47uF | 47u | tantalum; read from the layout by eye | |
| ×2 | 100uF | 100u | electrolytic; read from the layout by eye | |
| Diodes 2 | ||||
| ×3 | Germanium | GERMANIUM | D1-D3, part number not given; read from the layout by eye | |
| D4 | 1N5817 | 1N5817 | read from the layout by eye | |
| Transistors 2 | ||||
| Q1 | MP20A | MP20A | MP20A or other PNP Ge w. low leakage, Hfe 50-70; read from the layout by eye | |
| Q2 | BC108B | BC108B | BC108B/C; read from the layout by eye | |
| ICs 1 | ||||
| IC1 | TLC274 | TLC274 | read from the layout by eye | |
| Potentiometers 5 | ||||
| Gain | A100K | A100k | Potentiometer | read from the layout by eye |
| Texture | B10K | B10k | Potentiometer | read from the layout by eye |
| High | B5K | B5k | Potentiometer | read from the layout by eye |
| Low | B5K | B5k | Potentiometer | read from the layout by eye |
| Level | A50K | A50k | Potentiometer | read from the layout by eye |
| Trimmers 1 | ||||
| ×1 | 100K | 100k | read from the layout by eye | |