Found in Popular Electronics from the 90s, this circuit detects modulated infrared radiation and serves as a test for remote controls. Infrared sensors equivalent to the one indicated can be used.
This small crystal microphone transmitter was indicated in an 80s spy book. The range depends on...
This circuit, found in a 1978 publication, converts 5 V into a symmetrical 15 V output under low...
The configuration shown in the figure is one of the most traditional when it is desired to produce...