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 is from an English magazine of 1977. The circuit is still current, just using BC547...
The adjustment of the maximum load voltage is made in the trimpot. The circuit is from 1994...
In the figure we have the conventional configuration of a differential amplifier with the...