This circuit, which can be found elsewhere on this site, detects positive pulses of a signal. The circuit was suggested in Texas Instruments documentation from the 1980s.
This circuit uses unijunction transistors and drives a small speaker through an output...
This circuit, found in a publication from the 1980s, can have its output voltage determined by the...
The operational amplifier for this circuit, found in a 1979 publication, may be the 741....