Operated directly from the power grid, this detector was found in an 80's RCA documentation. The sensor is an ionization chamber. The SCR triggers a warning siren.
We found this circuit for guitar training in an English documentation from 1989. The components are from...
This circuit produces a voltage drop in the first pulse, turning off the relay. On the second...
Readers who like sound or sound effects cannot fail to examine this interesting circuit. What we...