This circuit, from the 70's, can be assembled with a more modern FET like the BF245. The circuit is powered by a 9 V battery, as its consumption is very low.
According to its author, this device indicates the amount of force applied to the sensors. The...
This low frequency doubler requires a 50 mV signal at the input. The circuit is from an old...
This is a circuit that should not be used for readers interested in a fair game. The circuit...