Roland FD-8 Issues: Hall Sensor Modification
From Just in Time
Both editors of the Justinintime pages have a Roland TD-3 electronic drum kit. This kit plays quite nicely, but after some years the responsiveness of the High-hat pedal seems to worsen. We are not the only ones who have noticed this; google for 'roland fd-8 issues' to find widespread complaints and hacks/solutions people have come up with.
Most solutions have to do with adjusting the mechanical pressure on the variable film resistor in the pedal. Vincent wanted to completely get rid of the film resistor and replace it with an electronic alternative that has no contact issues. The obvious choice was a (linear) Hall Sensor. The first draft designs were MCU based with ADC and programmable variable resistor, but after some more clever thinking it became clear that a circuit with two comparators and two analog switches would work just as well.
The prototype works fine now, we hope to have some more details on this page soon.