This pocket-sized VHF receiver was found in Radio Electronics magazine from January 1961. It uses a transistor and tunes to the 11-meter band, considered VHF at the time.
This circuit, obtained from old documentation, doubles the frequency of the pulses applied to the...
The passage of an object in front of the LDR, producing a shadow or even turning off the ambient...
The CMOS TLC555 [equivalent to the bipolar 555] can be used as a monostable in the configuration...