When the bell push is pressed, the HT12E encoder converts the button press into a coded serial stream that modulates the 433MHz transmitter. The receiver demodulates the signal, the HT12D decoder validates the address, and the NPN transistor drives the doorbell speaker.
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Separate 3V battery domains for transmitter and receiver eliminate wiring between the pushbutton and the bell, and prevent ground loops.
A base resistor R1 limits current from the decoder output into Q1, protecting the decoder while ensuring saturation.
Using generic ICs with explicitly declared pin roles makes the encoder/decoder and RF module connections readable without hiding RF details.
Reuse this netlist when modelling low-power RF alert or remote doorbell systems where a momentary switch must trigger an audible output through a coded wireless link.