The power supply for this 1972 circuit must be symmetrical and the BC549 transistors. Care with the layout is important to avoid capturing tinnitus.
This circuit is from RCA documentation from the 70s. The dual-gate MOSFET is not very easy to...
Found in a Popular Electronics from the 90s, this circuit uses a double 555 to emit beeps when the...
This source, obtained in a 1973 publication, uses a low power transistor to regulate the output...