This circuit is a modification of the previous one, also found in the July 1995 Electronics Now magazine. The triac must be according to the controlled power.
This filter that rejects determines frequency (notch) was found in a Popular Electronics of 1993....
Found in an Elektor from the 90's, this double door-bell drive circuit switches a relay by...
Using a 555 this circuit was found in old documentation, but it is still valid. | Clique na imagem...