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Birdie Doorbell Ringer: (schematic / circuit added 10/02) |
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Ding-Dong Bell: (electronic Circuit / Schematic added 10/04) |
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Door Chime: This is a circuit that could be used as a doorbell system like those that most homes have. From what I can
tell, pressing the switch triggers the IC to oscillate and send electricity through the transistors to power the speaker. The IC type is not listed, but I am guessing that it is a 555 Timer.
(schematic / circuit added 10/06) |
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Doorbell for the Deaf (mitedu): (electronic design added 10/06) |
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Doorbell for the Deaf: (schematic / circuit design added 9/02) |
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Doorbell with Counter: (circuit added 7/02) |
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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) |
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Fix Adds Door-Chime Repeater: 05/13/99 EDN-Design Ideas / (added 11/05) |
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Multi-Switch Doorbell with Indicators: (electronic Circuit / Schematic added 10/04) |
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Remote Doorbell Indicator: (schematic / circuit design added 9/02) |
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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) |
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Self-Powered Door-Bell Watcher: Detects if the door-bell has rung in your absence. Also suitable to different electric apparatuses. (added 4/05) |
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Simple Fix Adds Door-Chime Repeater: 05/13/99 EDN-Design Ideas / (added 11/05) |
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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) |