Found in Maxim's documentation from the 90's, this circuit uses an integrated from the time providing a 12 V output from 10 to 12 V inputs.
We found this circuit in the 1983 Radio Electronics Special projects magazine. The components are...
With the presented circuit it is possible to detect signals from transmitters in a frequency range...
This circuit was found in a British documentation from 1969. It can be implemented with modern...