This circuit was found in a Popular Electronics from the 90's. The CMOS integrated circuit used is not very common nowadays. The range depends on the infrared LEDs. R7 can be changed.
Found in American documentation from the 1990s, this circuit generates signals in the 350 to 500...
This instrument was obtained in a documentation for radio amateurs of 1976. The circuit measures...
This circuit was suggested by Motorola in 1980s documentation. The circuit employs an operational of...