Very strong audio spikes in a headset can damage the ear. This circuit, from a 90s Popular Electronics cuts them, being originally indicated to operate with an integrated amplifier of the time.
This circuit was found in old documentation. It can be made based on modern components. The time...
This small two-transistor AM radio was sold in the 1960s in Japan. The circuit was powered by two...
I found this circuit in an old English magazine from 1979, but it can be easily assembled with...