This module is part of my Eurorack series. It is a simple utility module that inverts a given voltage in a range of -12V to +12V and is also capable to attenuate it and add an offset to it.
Buy PCBs in my storeKey features#
- dual inverter
- attenuator
- offset voltage (-12V to +12V)
- easy to build, all through hole components
- 6HP
How it works#
The module is based on a simple inverting op-amp configuration. The input voltage is mirrored at 0V; voltage range is from -12V to +12V. In addition it is possible to attenuate the input voltage with a potentiometer which is acting as a variable voltage divider. An offset voltage ranging from -12V to +12V can be added to the input voltage. The output voltage is clipped when the operational voltage ranges of the op-amp are reached. Both inverters can be connected in series to have a copy of the input voltage plus offset.
Assembly#
The build is pretty straight forward. The module only consists of through-hole components and is easy to assemble. There are two boards: a front panel and a board for controls/jacks and the inverting op-amp circuitry.
First, solder all components on one side of the circuit board. Keep the jacks and potentiometers for the end. Begin with the components with the lowest profile and work your way up. Screw the jacks and potentiometer to the front panel before soldering them. All components have a fixed designator and a component value printed on the board. Additional information on the parts can be found in the BOM below.
See the Component Basics guide for help identifying parts.
BOM#
| Reference | Value | Footprint | Description | Qty |
|---|---|---|---|---|
| C1, C2 | 10u | Capacitor_THT:CP_Radial_D5.0mm_P2.50mm | electrolytic | 2 |
| C3 | 100n | Capacitor_THT:C_Disc_D3.0mm_W2.0mm_P2.50mm | ceramic | 1 |
| J1 | IN1 | Connector_Audio:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles | Thonkiconn 3.5mm jack sockets | 1 |
| J2 | IN2 | Connector_Audio:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles | Thonkiconn 3.5mm jack sockets | 1 |
| J3 | OUT1 | Connector_Audio:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles | Thonkiconn 3.5mm jack sockets | 1 |
| J4 | OUT2 | Connector_Audio:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHoles | Thonkiconn 3.5mm jack sockets | 1 |
| POWER1 | Conn_02x05_Odd_Even | Connector_IDC:IDC-Header_2x05_P2.54mm_Vertical | IDC 10-pin | 1 |
| R1, R2 | 10 | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | 1/4W 1% resistor | 2 |
| R3, R4 | 1k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | 1/4W 1% resistor | 2 |
| R5-R10 | 100k | Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal | 1/4W 1% resistor | 6 |
| RV1 | 100k LEVEL2 | Potentiometer_THT:Potentiometer_Alpha_RD901F-40-00D_Single_Vertical | linear, vertical, threaded, 6mm | 1 |
| RV2 | 100k LEVEL1 | Potentiometer_THT:Potentiometer_Alpha_RD901F-40-00D_Single_Vertical | linear, vertical, threaded, 6mm | 1 |
| RV3 | 100k OFFSET2 | Potentiometer_THT:Potentiometer_Alpha_RD901F-40-00D_Single_Vertical | linear, vertical, threaded, 6mm | 1 |
| RV4 | 100k OFFSET1 | Potentiometer_THT:Potentiometer_Alpha_RD901F-40-00D_Single_Vertical | linear, vertical, threaded, 6mm | 1 |
| U1 | TL072 | Package_DIP:DIP-8_W7.62mm_Socket_LongPads | through hole | 1 |
Schematics#
