D/MOD is a vicious modulation effect that uses a CD4046 to generate frequencies to modulate an input signal. Effect knob controls how much of the output signal is fed back to the input stage of the circuit. Bias knob and CV input control the reference voltage for the CD4046, creating really harsh, distorted modulation effects.
Started off as an experiment with the Barton Musical Circuits 4046 Wave Shaper, but de-evolved into something less complex. Less complex, but definitely noisier.
Switches for color and range affect the modulating frequency ranges. Demod switch feeds part of the signal back to the demodulation pin of the CD4046, providing an additional mode of performance. Effect is most pronounced with waveforms that have a lot of headroom for overtones (e.g., sines and triangles).
Due to the biasing method employed (which might be counterindicated by common practice and good sense), CV works best with bipolar signals.
Schematic
As with any schematic found on the internet, exercise caution when building. Test the build before plugging it into your case. If you find mistakes in the schematic, or you have recommendations for improving the design, feel free to contact us and let us know.
BOM
- Capacitors
- 1nf (1) C2
- 4.7nf (1) C1
- 1uf (1) C3
- Resistors
- 1k (1) R11
- 5.6k (1) R5
- 7.5k (2) R7, R12
- 10k (4) R6, R8, R9, R10
- 47k (1) R2
- 100k (5) R1, R3, R4, R13, R14
- Potentiometers
- 1k (1) RV1 (Effect)
- 10k (1) RV2 (Bias)
- ICs
- TL071 (1) U1
- CD4046 (1) U2
- TL072 (1) U3
- Audio jacks (3) J1, J2, J3
- Switches
- SPDT (3) SW1, SW2, SW3