This electronic rheostat with SCR was found in the June 1964 Radio Electronics magazine. The SCR may be a modern type and the 2W potentiometer may be 470 ohms.
This circuit is a variation of the common grid dip meter, having been found in a 1975 publication on FETs....
Found in old documentation, this circuit applies to almost any common operational amplifier or...
This circuit with 10 MHz and 1.25 MHz TTL outputs was found in an American documentation from the...