Diode Ladder Filter Schematic. This filter has a sound of its own and is the signature of the classical pink floyd s song on the run. State variable filter with ca3080 as ota and ca3140 as buffer schematic module 703e f g.
A 2k trimmer is added in series with r18. Actual filter measurements have excellent agreement with the theoretical frequency response. The schematic at right shows a simplified diode string filter.
Now this is a little bit tricky to arrange since the diodes need to be fed current in order that they act as a resistor.
Look at the physical ladder with the capacitors pointing up at you. A 2k trimmer is added in series with r18. To limit the current in the diodes we need to use some resistance r2. The diode ladder filter was originally designed for the ems vcs3 synth but is most famous as the resonant filter from the roland tb 303 bassline monophonic synth.
