This control circuit using a low voltage switch was found in the September 1987 Radio Electronics magazine. The triac must be matched to the load and the mains voltage.
In this phase shift circuit, the transistor can be any general-purpose transistor. The circuit is from...
This circuit is from an old Mullard (Philips) manual with applications using the 555. Choosing...
This simple TTL digital amplifier uses NAND gates and a high impedance speaker. ...