Found in an Electronics World of 1966, this circuit makes use of FETs of the time. Modern equivalents can be used. The high voltage supply suggests its use with tube amplifiers.
This circuit is from a 1974 publication by Motorola. The unijunction may be 2N2646 and bipolar BC558...
The figure shows how to obtain a higher output current for an operational amplifier. With the...
This voice scrambling scrambler was published in the August 1982 issue of Radio Electronics...