This converter was found in the June 1991 issue of Radio Electronics magazine. The circuit uses common circuits at the time and its operating range can be changed.
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...