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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  NEW
  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... 

Birdie Doorbell Ringer:  (schematic / circuit added 10/02)

Ding-Dong Bell:  (electronic Circuit / Schematic added 10/04)

Doorbell for the Deaf (mitedu):  (electronic design added 10/06)

Doorbell for the Deaf:  (schematic / circuit design added 9/02)

Doorbell with Counter:  (circuit added 7/02)

Electronic Canary (Doorbell):  This circuit is a modified "Hartley Oscillator" with a couple extra parts.  T1, the LT700 (or equivalent, is a small center tapped (ct) audio transformer with an impedance of 1000 ohms at 1000 hertz.  The secondary of this transformer has an impedance of 8 ohms.  Usually noted as 1K:8 ct.  I tried a couple other models like the red and green types (taken out of a $5 made-in-china am pocket radio) and they both work good.  You may have to adjust the caps to get the sound... (added 2/06)

Fix Adds Door-Chime Repeater:  05/13/99 EDN-Design Ideas / (added 11/05)

Multi-Switch Doorbell with Indicators:  (electronic Circuit / Schematic added 10/04)

Remote Doorbell Indicator:  (schematic / circuit design added 9/02)

Remote Doorbell Warning Switch:  This circuit should only be used with the solenoid type chime doorbells, the electronic type that play tunes will not work here. The hardest part for this circuit was the title. It is quite easy to miss the sound of a doorbell if you are watching TV , this circuit gets round the problem by providing a visual indication, i.e. a lamp. As an alternative, a LED could also be used. You could just parallel a lamp across the doorbell, but this would mean extra drain from the doorbell batteries or transformer. (added 2/06)

Self-Powered Door-Bell Watcher:  Detects if the door-bell has rung in your absence.  Also suitable to different electric apparatuses. (added 4/05)

Simple Fix Adds Door-Chime Repeater:  05/13/99 EDN-Design Ideas / (added 11/05)

Two Tone Generator:  This two-tone generator includes 3 ICs NE555 Astable Multivibrators. You can vary the duration of each tone by changing the 10k resistor or 100MF capacitor at IC1 or changing resistors and capacitors at IC1/2 for higher or lower tone. (added 6/03)