This circuit was found in a publication by Edelman from 1924. The power comes from the battery and the listening is through a high-impedance headphone.
This circuit was found in a 2005 Linear Technology manual. It senses the two-way current,...
This circuit was found in an Electronics Now from the 90's. See the previous article for the...
This is the basic configuration of a monostable TTL with the 74121. The trip is done with an NC...