Enclosure not stated · 2 knobs
Baja Optical LimiterVerified
Based on the BAJA Optical Limiter· 2 other boards clone it
- Category
- Compressor
- Controls
- Limit · Level
- Build
- Perfboard
- Layout
- Verified · Effects Layouts (blog) marks it as built and working
- Tags
- Baja, Limiter
From the post
Here's one of Bajaman's non-amp emulating circuits, the Optical Limiter. It's based on the Demeter Compulator, but is not a compressor but a limiter. What's the difference?
The ratio is the main difference between a compressor and a limiter. A compressor has a low ratio that turns down SOME of the volume when it goes above the threshold. A limiter has a huge ratio that turns down ALL of the volume that goes above the threshold. (from Musician on a Mission)
Here's the schematic for reference. It's designed as a buffered bypass pedal, with the input jack going to the In pad on the board, and a third of a a 3PDT footswitch selecting between the buffered out and effect out. The off board LED pulses with the signal but probably isn't going to be great as an on/off indicator. Just use another third of the 3PDT to make/break the connection between the LED- pad and the cathode of the LED. And then use the final third of the footswitch to wire an on/off indicator LED as you normally would. (At least I think that's what Bajaman had in mind...) Also, the LDR should have 5k light resistance, 500k dark resistance (a GL5516 should work). Oh, and I added an extra pad so GSD pinout JFETs (J201, 2N5457, etc.) can be used in place of the 2SK117.
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 Effects Layouts (blog). No KiCad fragment has been drawn for this circuit yet.
Parts list 25 rows
Report a wrong parseGot parts in a drawer? See what you can build with them.
| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 11 | ||||
| ×2 | 1K | 1k | read from the layout by eye | |
| ×2 | 1.5K | 1.5k | read from the layout by eye | |
| ×2 | 100K | 100k | read from the layout by eye | |
| ×4 | 10K | 10k | read from the layout by eye | |
| ×1 | 2.7K | 2.7k | read from the layout by eye | |
| ×2 | 68K | 68k | read from the layout by eye | |
| ×5 | 560Ω | 560 | read from the layout by eye | |
| ×2 | 4.7K | 4.7k | read from the layout by eye | |
| ×1 | 100Ω | 100 | read from the layout by eye | |
| ×2 | 47K | 47k | read from the layout by eye | |
| ×1 | 1M | 1M | read from the layout by eye | |
| Capacitors 5 | ||||
| ×1 | 220uF | 220u | electrolytic; read from the layout by eye | |
| ×2 | 10uF | 10u | electrolytic; read from the layout by eye | |
| ×2 | 1uF | 1u | box film; read from the layout by eye | |
| ×1 | 100nF | 100n | read from the layout by eye | |
| ×1 | 10nF | 10n | read from the layout by eye | |
| Diodes 2 | ||||
| ×1 | 1N4001 | 1N4001 | read from the layout by eye | |
| ×2 | 1N4148 | 1N4148 | read from the layout by eye | |
| Transistors 1 | ||||
| Q1 | 2SK117 | 2SK117 | JFET; read from the layout by eye | |
| ICs 1 | ||||
| ×2 | LF353N | LF353N | read from the layout by eye | |
| Opto 1 | ||||
| ×1 | LDR | LDR | type not given; read from the layout by eye | |
| Potentiometers 2 | ||||
| Limit | B10K | B10k | Potentiometer | read from the layout by eye |
| Level | B10K | B10k | Potentiometer | read from the layout by eye |
| LEDs 2 | ||||
| ×1 | 5mm yellow | 5MM YELLOW | on board, faces the LDR; read from the layout by eye | |
| ×1 | 5mm yellow | 5MM YELLOW | off-board, LED+/LED- pads; legend 'LEDs: 5mm yellow'; read from the layout by eye | |
Other boards based on the BAJA Optical Limiter
- Bajaman LA2A Style Optical Limiter rev2 Revolution Deux
- Madbean Holy Roller / Baja Optical Limiter Tagboard Effects