Found in American documentation from the 1980s, this circuit uses transistors from that time. It generates increasing and decreasing tones when we press and release the push button.
Only incandescent lamp can be used in this circuit. The SCR must be mounted on a heatsink and...
This circuit originally appeared in a publication of 1997. With the changes, the circuit can be...
This circuit is from a 1969 Electronics World. The transistors may be modern general-purpose...