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Basement Doorbell Beeper
If you can't hear your doorbell when you are in your basement try this
circuit. This circuit takes advantage of the 24vac power source located near
the furnace. Using a simple current transformer technique, the circuit sounds
a beeper whenever the main door chime is activated.
Basement Doorbell
This circuit will activate a beeper in the basement, whenever the front
doorbell is pressed.
Door Knock Beeper
In some apartment buildings and homes, not equipped with a door bell, it may be hard to
hear someone knocking on the front door. The circuit below provides a means to activate
a loud beeping sound inside, whenever someone knocks on the door from the outside. The
circuit is powered by a 9v battery, which should provide years of service. An on/off
switch allows the device to be turned off if desired....
Star Trek Doorbell
In the Star Trek “Next Generation” TV series, the doorbell outside the private quarters
of a crew member makes a particular “beep-boop” sound. The 3v battery powered circuit
below tries to simulate this sound. The circuit uses one 74HCT74 dual D flip/flop IC,
wired as two one-shot circuits. Both are designed to produce a pulse about one half
second long. The first pulse turns on a 555 timer to form the beep sound. The second
flip/flop one shot....
