This frequency division multiplexing signal decoding circuit is from a 1980s documentation. The integrated circuit used is not very common today.
This circuit found in a 1964 US publication reverses the signal level by providing 9 to 0 V...
This circuit is from 1967 General Electric documentation. It uses SUS which are not very common...
August 2017 - MCUs of the new Infineon MC1400 series for industrial use can now be purchased from...