Bass control (CB8722E)

Found in a 1993 Electronics Hobbyst Handbook, this passive circuit can be used with common preamplifiers and amplifiers.

Transistor Replacement Box (CB21670E)
The idea of this circuit from a 1960 publication is simple: we can switch the transistor being...
LM3914 Audio Level Meter (CB25459E)
Using a small speaker as a microphone, this 10-LED circuit was found in the March 1992 issue of...
2 W Amplifier LM380 (CB13758E)
We found this circuit in a 1977 documentation. The National Semiconductor's LM380 is no longer...