The circuit presented was obtained in a technical documentation from National Instruments. The low-consumption circuit supplies a common LED with a voltage of just 1.5 V.
Any general-purpose germanium or silicon PNP transistor can be used on this receiver. The handset...
When this circuit is activated the LED flashes for a moment indicating that the function has been...
In the circuit of the figure, when pressing S1 the sound varies according to the value of R2 and...