We found this code switch circuit in the January 1999 Electronics Now magazine. Some of the components are integrated circuits from that era.
This circuit has a voltage gain of 30 times and passband of 14 MHz. The circuit is from the 1974...
In the figure we have an oscillator circuit by Wien Bridge (Wien Bridge Oscillator). The frequency of...
This timer with 1 second accuracy was obtained in a 1973 documentation. The Buzzer is a low-power type...