These days, 433-MHz RF transmitter/receiver modules are very popular with electronics hobbyists and tinkerers. These cheap short-range radio modules can be used with almost all microcontrollers for a ...

Conceptually the circuit there is simple, consisting of the ultrasonic receiver, followed by a transistor amplifier for the modulated wave, then a diode for demodulation, another transistor ...

But this time the receiving side was swapped out, as [GreatScott] built a basic circuit around a TA7642 AM amplifier/demodulator IC, with only six passive components and a hand-wound coil.

The receiver is equally simple and also based on a CMOS 555. As long as the sensor picks up infrared light from the transmitter, the reset input of the 555 IC is held low and the buzzer is silent.

Electronic Circuits and Tubes By the Electronics Training Staff of the Cruft Laboratory, Harvard University. Pp. xxiv + 948. (New York and London : McGraw-Hill Book Co., Inc., 1947.) 45s.

This circuit uses the EUSART (Enhanced Universal Synchronous Asynchronous Receiver Transmitter) modules embedded in two PIC microcontrollers 16F1619 and 16F1614. The communication is full-duplex ...