This circuit was obtained in a 1964 Electronic Design. The components used are from that time. Observe the high voltage used in the supply.
This twisted pair exciter circuit uses 80's components. The circuit is from a documentation of the time, but...
Found in a 1967 Electronics World, this circuit can use any modern equivalent FET. Observe the...
What this interesting circuit does is to warn that a note written on a paper has been removed and...