We found this receiver circuit for modulated light in a 90s Popular Electronics. Equivalent audio amplifiers can be used. Transistors are commonly used.
This circuit is from a 1974 publication. It generates a pulse with several sinusoidal cycles from...
This 1000: 1 voltage-controlled filter circuit was found in an Electronics Today International in a 1980s...
This is the traditional configuration of the 7806 as a 12 to 6 V automotive voltage reducer. The...