This circuit was found in a 1980s US publication. It indicates when the phone is off-hook by triggering an indicator.
This circuit using a SIDAC is suggested by ON Semiconductor in its thyristor manual. The circuit...
This circuit generates signals controlled by crystal and can generate marks up to 30 MHz of 1 in 1...
You can program the 4018 in other ways, as shown in the figure. In this 7 divider configuration, for...