Raytheon's used integrated circuit is no longer common today. The circuit was obtained in a documentation from the 80's and must be powered by a symmetrical source.
This sensor circuit from a 1967 Ferranti documentation uses components from the era. The circuit...
This is the receiver for the previous circuit transmitter. Similarly, no information about the...
Found in a 90s Popular Electronics, this circuit uses two PLL tone recognizers to trigger by touch an...