This organ, played by a probe was found in no old documentation, but it can be easily implemented these days. The integrated circuits are 555. The trimpot allows individual tuning of the keys.
The figure shows how to use an LM3914 with a variable range moving point. The circuit has an...
This circuit was found in a 90s Popular Electronics. It uses a varicap that admits equivalents. The...
This circuit is from an Electronics Now from 1998 and can be easily assembled with other JFET...