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Eurorack Inverter

Eurorack Modular Inverter Utility Easy-Build Through-Hole

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.

The PCBs are available in my store

Key features
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  • dual inverter
  • attenuator
  • offset voltage (-12V to +12V)
  • easy to build, all through hole components
  • 6HP

How it works
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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
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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.

BOM
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Link to interactive BOM

ReferenceValueFootprintDescriptionQty
C1, C210uCapacitor_THT:CP_Radial_D5.0mm_P2.50mmelectrolytic2
C3100nCapacitor_THT:C_Disc_D3.0mm_W2.0mm_P2.50mmceramic1
J1IN1Connector_Audio:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHolesThonkiconn 3.5mm jack sockets1
J2IN2Connector_Audio:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHolesThonkiconn 3.5mm jack sockets1
J3OUT1Connector_Audio:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHolesThonkiconn 3.5mm jack sockets1
J4OUT2Connector_Audio:Jack_3.5mm_QingPu_WQP-PJ398SM_Vertical_CircularHolesThonkiconn 3.5mm jack sockets1
POWER1Conn_02x05_Odd_EvenConnector_IDC:IDC-Header_2x05_P2.54mm_VerticalIDC 10-pin1
R1, R210Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal1/4W 1% resistor2
R3, R41kResistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal1/4W 1% resistor2
R5-R10100kResistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal1/4W 1% resistor6
RV1100k LEVEL2Potentiometer_THT:Potentiometer_Alpha_RD901F-40-00D_Single_Verticallinear, vertical, threaded, 6mm1
RV2100k LEVEL1Potentiometer_THT:Potentiometer_Alpha_RD901F-40-00D_Single_Verticallinear, vertical, threaded, 6mm1
RV3100k OFFSET2Potentiometer_THT:Potentiometer_Alpha_RD901F-40-00D_Single_Verticallinear, vertical, threaded, 6mm1
RV4100k OFFSET1Potentiometer_THT:Potentiometer_Alpha_RD901F-40-00D_Single_Verticallinear, vertical, threaded, 6mm1
U1TL072Package_DIP:DIP-8_W7.62mm_Socket_LongPadsthrough hole1

Schematics
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