Using 3 ports, this rectangular oscillator was found in the March 1996 issue of Electronics Now magazine. The maximum frequency is a few megahertz, determined by R1 and C1.
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...