This circuit uses uncommon Texas Instruments components today. The circuit is from an American documentation. Transistors are commonly used PNP. The display is 7 segment multiplexed.
When S1 is pressed, the circuit allows music to be played from an audio source on the telephone line....
This circuit was found in an Experimenters Handbook of the 1990s. The purpose of this circuit is to...
The action of this circuit, found in a 1977 amateur radio documentation, is like to a delay line....