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.
This small crystal microphone transmitter was indicated in an 80s spy book. The range depends on...
The figure shows how to use an operational amplifier with a low impedance head. The gain is...
Voltage comparators, such as those in the LM139/239/339 series, consist of devices that can be...