Jürgen Haible
Polymoog® Resonator

Note:  The original Jürgen Haible website is no longer active but has beer reposted at http://www.jhaible.com.

This is the Polymoog® Resonator module as discussed on the Electro-Music forum.

 

There are 10 SMT capacitors on the rear of the PCB.

Polymoog® Resonator Mouser parts list

 

I added a three input mixer and changed the gain of the dry level to 2X (change R16 to 10K) so I could get unity gain through the module. There is a lot of gain in the resonator cells so it is easy to clip the waveforms.  There is less headroom on the positive waveform since the reference (e.g. virtual "ground") is +5 volts.  Some of the resonator waveforms are not symmetric so you can get either significant positive or negative clipping.   I wanted an indicator that would show clipping on either end so I used a pair of comparators to form a window detect at +12.5 volts and -2.5 volts (15 volts pk-pk centered about +5 volts).  The brightness of the LED indicates the amount of clipping.  I built the input mixer and the clipping circuits in the PCB vectorboard area.

Power consumption: 21 mA +15, 20 mA -15

Polymoog® Resonator modification wiring  updated

Polymoog® Resonator modification schematics  updated

 

I made a bracket out of 0.050" aluminum to mount the PCB.  It was nice to have the vectorboard area so I didn't have to mount a second PCB for my enhancements.

 

 

Operation

This scope image shows no clipping (magenta) on the resonance output of U4B pin 7 (cyan).  The gain controls are all near maximum level while the input control has been adjusted down to 2.5 volts pk-pk.

 

This scope image shows some clipping (magenta) on the resonance output of U4B pin 7 (cyan).  The clip LED brightness varies with the duty cycle of the clip signal to provide good indication as to the amount of clipping.

The input is at about 5 volts pk-pk.  I could reducing the gain controls and increase the input level as well.  The increased gain of the dry mixer compensates for the larger gain through the resonance cells.

 

 

Panel

I developed many front panel designs that are shown here.  This design uses small body BI Technologies and Vishay potentiometers so I could move the frequency controls (e.g. Low, Mid, and High) closer to the top edge.

Control Source Description
10K linear potentiometer Oakley Sound BI Technologies
10K log potentiometer Oakley Sound BI Technologies
10K dual linear potentiometer Oakley Sound Vishay 149.DXG56S103SP
1 pole 4 position rotary switch Mouser 105-13571 30° 2-12 position shorting

Polymoog® Resonator FrontPanelDesign file

 

 

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