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Counter with Doorbell - This circuit uses a synthesized
sound chip from Holtek, the HT-2811. This reproduces the sound
of a "ding-dong" chiming doorbell. Additionally, the circuit
includes a CMOS 4026 counter display driver IC to count your
visitors. |
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Ding-Dong Bell |
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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.....
[Designed by David A. Johnson] |
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Doorbell Chime |
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Doorbell for the Deaf - This circuit provides a delayed
visual indication when a door bell switch is pressed. In
addition, a DPDT switch can be moved from within the house which
will light a lamp in the door bell switch. The lamp can
illuminate the words "Please Wait" for anyone with walking
difficulties..... by Andy Collison] |
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Doorbell Indicator - 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.... [Circuit Design
by Andy Collison] |
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Doorbell with Counter - This circuit uses a synthesized
sound chip from Holtek, the HT-2811. This reproduces the sound
of a "ding-dong" chiming doorbell. Additionally, the circuit
includes a CMOS 4026 counter display driver IC to count your
visitors.… by Andy Collison] |
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Electronic Canary Doorbell - This circuit is a modified
"Hartley Oscillator" with a couple extra parts. T1, the LT700
(Tony van Roon's or equivalent, is a small center tapped (Tony
van Roon's 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 (Tony van
Roon's 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..... [Tony van Roon's circuit] |
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Fix Adds Door Chime Repeater - 05/13/99 EDN-Design
Ideas.....Electromechanical door chimes can enhance your home,
but they are vulnerable to costly repair problems. A defective
pushbutton switch or a careless visitor can maintain the chime
in an energized state for a prolonged period, thereby damaging
the chime. The circuit in Figure 1 prevents damage to the chime
and improves the chime's effectivenessElectromechanical door
chimes can enhance your home, but they are vulnerable to costly
repair problems. A defective pushbutton switch or a careless
visitor can maintain the chime in an energized state for a
prolonged period, thereby damaging the chime. The circuit in
Figure 1 prevents damage to the chime and improves the chime's
effectiveness..... [Design Idea by Dennis Eichenberg, Parma
Heights, OH] |
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Multi-Switch Doorbell with Indicators |
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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.....
by Andy Collison] |
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Self-powered Fast Battery-Tester - Tests 1.5 to 15 Volt
cells. Two-LED display, no power supply required. |
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Simple fix adds door-chime repeater - 05/13/99 EDN-Design
Ideas.....Electromechanical door chimes can enhance your home,
but they are vulnerable to costly repair problems. A defective
pushbutton switch or a careless visitor can maintain the chime
in an energized state for a prolonged period, thereby damaging
the chime. The.....PDF contains many circuits, scroll to find
this one.… [Design Idea by Dennis Eichenberg, Parma Heights, OH] |
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Three Flashing LED Doorbells - These circuits combine a
buzzer with one or more LED displays. When the push switch is
operated, the buzzer will sound and the LEDs will flash. When
the switch is released, the buzzer will stop, but the LEDs will
go on flashing for another 30 seconds or so.,,, [Ron J.'s
circuit] |
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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. Designed by Andrew R. Morris |
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Universal Ding-Dong - One frequently finds gongs or chimes
for sale in antique shops or Eastern markets. But supposing one
would want to wire these to a pushbutton at the front door to
create a ding-dong doorbell? How would this be done? Or
consider, for a moment, more creative possibilities. How would
one e.g. cause wine-glasses or African drums to resonate when a
doorbell is pressed? The circuit shown in Fig. 1 provides a
mechanical means of striking two gongs or chimes in sequence --
one when the doorbell is pressed, the other when it is
released. This it does by briefly activating two solenoids
in..... [Posted by Jospfh] |
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Wireless Doorbell - The transmitter circuit is made up of
two building blocks, the 303MHz RF oscillator and the 32kHz
crystal controlled oscillator. The 303MHz oscillator consists of
a self-oscillating circuit made up of the coil. |
