The AttenuVerter is a dual-channel CV processor. It can attenuate, invert, and offset two independent control voltages.
I already published about “chicklet” Attenuator – Inverter. This time, however, it’s a full-featured module on a 4 HP wide front panel, with jack connectors, and the addition of an offset potentiometer per channel.
The circuit is slightly more complex, as there are now 3 op-amps per channel instead of just one. Since the two channels are strictly identical, I will only describe the first channel.
The first op-amp (U1A) is the most important, as it is responsible for the two main features of the module: inverting (or not) and attenuating the signal present at input jack J1. R1 sets the amount of gain. R2 and R3 modify the response of the potentiometer.
The second op-amp (U1B) introduces an offset voltage, set by potentiometer R7.
The third op-amp (U2A) isn’t part of the signal path. Its role is to drive the bi-color LED D1 properly.
The processed CV is then sent through protection resistor R12 to output jack J2.
Components
LEDs
The two LEDs should be bi-color types. Red/Green is a good combination. It helps visualize the positive and negative excursions of the individual output CV.
Potentiometers
Two types of potentiometers are required:
- Single-turn, linear potentiomers, with an add-on knob: for the attenuation/inversion setting (R1, R14)
- Single-turn, linear trimmers, with painted pointer on plastic shaft: for the offset setting (R7, R20)
Power connector
The power connector must be a simple unboxed 10-pin header. The reason is that one of the LEDs must be soldered next to this connector. With a boxed header, it wouldn’t be possible to solder the LED, and the solder joints would interfere with the connector’s housing.
The module is protected against reverse polarity, so don’t worry, even if you plug the power cable wrong, nothing serious will happen.
Documentation
- Schematics (attenuverter-1.0b-schematic-2026-03-03)
Interactive BOM (AttenuVerter-1.0b-ibom_no_fp-2026-03-27)- Interactive BOM (AttenuVerter-1.0b-ibom_no_fp-2026-08-02)