This circuit is from an old Popular Electronics, but it can be easily implemented nowadays, even adapted to act as a shield. The circuit has the frequency given by C1 and adjusted in R1.
ROHM Semiconductor is featured in a new line of IR LEDs, Proximity Optical Sensors and Ambient...
Found in a documentation by Hugo Gernsback from 1960, this receiver uses germanium transistors of the time...
In the figure we have the way to connect several 555 to obtain sequential operation. The component...