Benjolin - Rob Hordijk's Benjolin in the Eurorack format

• This is a DIY Eurorack project based on Rob Hordijk's Benjolin design.

Modifications

• Addition of an external audio input for the filter.
• Voltage-controlled pitch for both oscillators.
• Voltage-controlled frequency for the low-pass filter.
• Disconnection of T2 from the filter (Note: T2 can still be connected to the filter's CV input via cable).
• Integration of an SPST switch to select the current input (P1 or a -9~9V voltage with a potentiometer) for the BC547.

Voltage Outputs

• Tri1 Out: ~6Vpp
• Pul1 Out: ~12Vpp
• Tri2 Out: ~6Vpp
• Pul2 Out: ~12Vpp
• PWM Out: ~18Vpp
• Main Out: ~2Vpp

Front Side of PCB

Back Side of PCB

Building & Troubleshooting

For further details and guidance, please refer to our comprehensive guide available here.

Acknowledgements

I extend my sincere gratitude to Rob for granting permission to adapt the Benjolin PCB for Eurorack use. His generosity is a significant contribution to the DIY synth community. His dedication and kindness are deeply appreciated.

License

Hardware: cc-by-sa-3.0

By: Tseng Kweiwen