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 booster for listening to signals in the range from medium waves to 30 MHz was found in a 1998...
In the figure we show our first circuit that consists of a simple touch switch capable of driving a...
Using a 7400 we have a short-wave transmitter from 4 to 9 MHz, shown in the figure. The coil...