status Draft
drc ok
erc ok
unconnected ok
Test: 4/4


steckfeld is a utility board for interfacing to the breadboard.


This is a preview of the elektrophon website, the content may not be accurate and is subject to change without any notice.
With steckfeld you can connect your synth to the breadboard. There are two input mixers and two output mixers. The reference voltage for the output mixer can be adjusted for level shift the signal.


This is a work in progress module and might not work as expected. Feel free to file a bug report on the github page.


I don't like working with breadboards. But sometimes you want to test things before you order a PCB. Connecting existing modules to the breadboard is especially tedious and building blocks like input mixer or output buffer occur in most circuits. This is where Steckfeld helps. It provides connectors for the patch cables and the necessary circuits for input and output. First, I made the resistors pluggable. But I never replaced them and finaly soldered them in.

the circuit of the attenuverter is based on the opamp dfferential amplifer. the two resistors at the non-inverting inputs are replaced with a potentiometer. the potentiometer is configured as a voltage divider and replace R3 and R4 from the differential amplifier. when the position of the potentiometer is adjusted, the output voltage will change or invert. at the center position the output is zero volrs. the response to the potentiometer is linear. we can make it an centered s-curve by adding two parallel resistors (R5,R6) to the potentiometer [[2][2]].

a simulation with the resistance at RV 1 changed from 0-100%. first run is the linear result. the second run is done with the resistors R5 and R6 added. This results in a s curve. the shape of the curve can be changed with the values of the resistors.

Figure 3: Steckfeld Board



2C1 C222uAluminium Electrolytic Capacitor, 35V, D=5 mm, LS=2 mm
6C3 C8 C9 C10 C11 C1247u (NP)Connector_PinSocket_2.54mm:PinSocket_1x02_P2.54mm_Vertical
4C4 C5 C6 C70.1uMultilayer Ceramic Capacitors MLCC
1J1IDC HeaderPin Header IDC, 10 Pos, 2.54mm
6J2 J3 J4 J5 J9 J10INelektrophon:Jack_3.5mm_WQP-PJ398SM_Vertical
3J7 J8 J11Conn_01x04_FemaleConnector_PinSocket_2.54mm:PinSocket_1x04_P2.54mm_Vertical
2R1 R210Resistor_THT:R_Axial_DIN0204_L3.6mm_D1.6mm_P2.54mm_Vertical
12R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14100kConnector_PinSocket_2.54mm:PinSocket_1x02_P2.54mm_Vertical
4RV1 RV2 RV3 RV4R_POTPotentiometer_THT:Potentiometer_Bourns_PTV09A-1_Single_Vertical
2RV5 RV6100kPotentiometer_THT:Potentiometer_Bourns_3296W_Vertical
2U1 U2TL072Package_DIP:DIP-8_W7.62mm_Socket








the input jacks are wired to 5 volts when nothing is connected.

all channels are mixed to the out jack. when something is connected to the channel out, this channel is removed from the overall mix.


  • connect the different channels from audio or cv sources to the in jacks.
  • connect the out jack to something
  • turn the pots clockwise to adjust the volume.


  • connect all or a single channel.
  • when you turn the pot knob counter clockwise the signal is inverted.