Enclosure not stated · 3 knobs
Park Auto WahVerified
Based on the Park Auto Wah· 1 other board clones it
- Category
- EQ / Filter
- Build
- Vero· 19×15· 13 cuts, 6 links
- Layout
- Verified · Dirtbox Layouts marks it as built and working
- Tags
- Colorsound/Solasound, Eq, Filter, Modulation, Park, Wah
From the post
Not an auto wah in a normal sense, more like an inductorless wah circuit driven by an LFO. This must be one of the earliest modulation pedals and IMO it is a hidden gem. Lots of murky psychedelic madness can be found in this circuit, especially with a dirt box upfront. Rate and Depth controls is self explanatory but the Tone control really widens the ranges of tones. Clockwise you'll get normal wah wah sweeps, roll it back and you can dial in vowel and yuo-yuo sweeps. With the Depth control CCW, the LFO is disengaged and the unit acts as a eq / filter circuit. Layout has some mods; power supply mod since original units was positive ground, CBE pinout for the transistors, power filer cap and protection diiode. As for the transistors, most low gain NPN silicons should work, I ended up with PN2222s in the 150Hfe ballpark. This is soon to be boxed but need to figure out how to add a rate LED first... *Edit* Rate LED added with help from Radu. Thanks!
Schematic is avaiable HERE
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 20 rows
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| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 6 | ||||
| ×4 | 100K | 100k | read from the layout by eye | |
| ×4 | 22K | 22k | read from the layout by eye | |
| ×4 | 4.7K | 4.7k | read from the layout by eye | |
| ×3 | 10K | 10k | read from the layout by eye | |
| ×1 | 220K | 220k | read from the layout by eye | |
| ×1 | 470K | 470k | read from the layout by eye | |
| Capacitors 5 | ||||
| ×2 | 1nF | 1n | read from the layout by eye | |
| ×2 | 10nF | 10n | read from the layout by eye | |
| ×3 | 2.2uF | 2.2u | electrolytic; read from the layout by eye | |
| ×3 | 10uF | 10u | electrolytic; read from the layout by eye | |
| ×2 | 100uF | 100u | electrolytic; read from the layout by eye | |
| Diodes 1 | ||||
| D1 | 1N5817 | 1N5817 | read from the layout by eye | |
| Transistors 5 | ||||
| Q1 | 2N3904 | 2N3904 | NPN Si, Hfe 100-300; try 2N3904, PN2222, MPSA06 etc.; 2N3702 (PNP) in original; read from the layout by eye | |
| Q2 | 2N3904 | 2N3904 | NPN Si, Hfe 100-300; try 2N3904, PN2222, MPSA06 etc.; 2N3702 (PNP) in original; read from the layout by eye | |
| Q3 | 2N3904 | 2N3904 | NPN Si, Hfe 100-300; try 2N3904, PN2222, MPSA06 etc.; 2N3702 (PNP) in original; read from the layout by eye | |
| Q4 | 2N3904 | 2N3904 | NPN Si, Hfe 100-300; try 2N3904, PN2222, MPSA06 etc.; 2N3702 (PNP) in original; read from the layout by eye | |
| Q5 | 2N3904 | 2N3904 | NPN Si, Hfe 100-300; try 2N3904, PN2222, MPSA06 etc.; 2N3702 (PNP) in original; read from the layout by eye | |
| Potentiometers 3 | ||||
| Speed | B50K | B50k | Potentiometer | read from the layout by eye |
| Tone | B5K | B5k | Potentiometer | read from the layout by eye |
| Depth | B5K | B5k | Potentiometer | read from the layout by eye |
Other boards based on the Park Auto Wah
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