This high-impedance headphone circuit was found in a 1990s William Sheets. The power is low, but the high input impedance makes it useful for radio applications.
This circuit makes use of a transconductance operational amplifier. It generates signals with TTL...
This circuit uses na Unijunction Transistor (UJT) to produce a modulation tone for several...
This circuit was found in General Electric documentation from the 1980s. The circuit uses couplers...