This circuit was found in an Electronics World of 1968. Its purpose in triggering a relay when the circuit receives signals from a vibration sensor. The circuit is used in emergency situations.
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...