This circuit is from 1985 documentation. The integrated circuit is not very common today, but modifications can be made leading to a project with current integrated circuits.
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...