With the circuit shown in the figure, it is possible to connect or disconnect a load controlled by the relay by touching the sensors X1 and X2.
This circuit is from 1997 Linear Technology Applications. The circuit uses common components at...
We found this elementary receiver in a 1983 publication, but it can be easily assembled today, as any...
This circuit has a type of bias called "virtual earth" providing good gain, given by R2. The...