Using the 4001 integrated circuit, this latching relay can employ any general-purpose transistor. The power supply is according to the relay with voltage up to 12 V.
This circuit can use a pendulum sensor. We found this configuration in a 1994 publication. The...
This circuit is from a 1964 Electronic Design. The sensor is an LDR and the transistors are...
This circuit works both as a preamplifier and activates a relay when speaking in front of the...