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.
In the figure we have the way to implement a voltage doubler in a simple source. The component values...
This circuit, which has a power of a few tens of microwatts, is suggested by Maxim. The circuit has a...
With the name of detectaphone, we find this circuit in a documentation from 1966. It will be...