Found in a 1980s American documentation, this circuit uses programmable unijunction transistors of the time. The time interval obtained depends on the capacitors that can be changed.
This circuit, suggested by National Semiconductor, is a tone control (bass and treble) with high...
This circuit from a Japanese publication in 1968 uses germanium transistors from the time like the...
This circuit is from a publication by Newton C. Braga in the United States. The transistor can be...