VIM Voltage Injecting Mixer

The voltage injecting mixer is a compact fully DC coupled two channel mixer module with the possibility to inject an +/- 8V offset on the incoming voltages.

Channel one has an attenuverter circuit which allows to invert or attenuate the incoming signal. The Attenuverters maximum gain can be set with a resistor on the board (Gain +/- 1 or +/- 2).

Channel two is fed right away into the summing circuit of the module.

If there are no signals connected at the channel inputs the module simply acts as an offset voltage generator.

The final output voltage is displayed by the backlit syringe on the frontpanel. Red indicates positive voltages, green indicates negative voltages.


Tunable Parameters:

  • ATV (sets the gain of Channel 1)
  • OFFSET (adds offset to the outgoing signal)


  • IN is the input jack for channel one
  • IN2 is the input jack for channel two
  • OUT is the summed output of IN, IN2 and the OFFSET voltage


  • +12V 5mA / -12V 5mA


  • Width: 4 HP (20mm)
  • Depth: 13mm

Check it out in the shop: VIM Kit – Voltage Injecting Mixer

Download the workshop documentation with explanations, schematics and pick and place infos:

TL074              U1                                      1.00          Mouser 511-TL074ACDT SO14 / 595-TL074CPWR TSSOP14
Resistor           R8, R9                                  2.00 2k2      ?
Resistor           R5, R7                                  2.00 10k      ?
Resistor           R1, R2, R3, R4, R6, R10, R11, R12, R13  9.00 100k     ?
Pinhead 10Pole     PWR                                     1.00          Farnell 1593451
Inductor PSU 100nH L1, L2                                  2.00 100nH    Mouser NLCV32T-R10M-PFR
Phonejack          IN, IN2, OUT                            3.00          Qinpu Electronics
LED                D1, D2                                  2.00          Mouser 1716696 old part 859-LTW-420D7
Capacitor 0805     C3, C4                                  2.00
CAP PSU            C1, C2                                  2.00 22uF     Mouser 667-EEE-FK1C220R
Pot Stereo 50k lin ATV, OFFSET                             2.00 50k lin  Alpha Taiwan Electronics