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24V DC Powered Beeper with 4 Separate Inputs
24v DC is a very popular voltage used in industrial settings. The circuit
below was designed to accept four different 24v DC alarm input signals, which are
then used to drive a single low power beeper. The beeper is a magnetic type
with its own oscillator/driver. The four diodes form an “OR” gate so any one
of the four inputs will cause the beeper to make noise. A CMOS version of the
popular 555 timer is used to strobe the beeper on and off at about 1Hz.
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- 3V Sweeping
Siren Alarm
The circuit uses a LTC1799 precision frequency
generator from Linear Technology. A 74HC14 hex Schmitt trigger from Texas
Instruments is also used to perform several other functions. One section is
wired as a simple 7Hz square wave oscillator....
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ANOTHER VERY LOUD PIEZO ALARM BEEPER
This is yet another beeper circuit that really draws attention. It sweeps the drive
frequency slightly to produce a very annoying sound. It uses a transformer to
increase the drive voltage across the piezoelectric device to more than 200 volts
peak to peak. It cranks out an ear splitting 120db when measured at 12 inches.
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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.
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- Basement Doorbell
This circuit will activate a beeper in the basement, whenever the front doorbell is
pressed.
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Check Engine Beeper
When wired into a
car’s indicator light panel, this circuit will turn on a loud beeper when the “check
engine” light turns on. (added 7/06)
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- Front Desk Service Beeper
This device functions like a lobby
desk service request bell. A short beep is sounded whenever the large
pushbutton on top of the device is pressed. Once pressed, the device will not
make another beep until at least 2 minutes of time has elapsed. This prevents
impatient customers from ringing the bell over and over.
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HIGH
SOUND OUTPUT BEEPER CIRCUIT
I you need a real loud beeper, this circuit delivers about 110db (12 inches away)
from a 9v battery using a single inexpensive C-MOS IC. An off-the-shelf
piezoelectric beeping device is driven at resonance to insure maximum efficiency. By
changing the control IC to a 74AC14, the same circuit can operate from 3v and 1.5v
batteries. Published in Electronic Design, Aug 5, 1993
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MACHINE POWER LOSS BEEPER
For some medical equipment it is important for an operator when power is lost to the
machine. The beeper is powered from a 9v battery and requires the machine to have a
power switch with a third set of contacts.
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- Piezoelectric Triggered
Switch
Two different switch circuits are shown. One sources current and the second
sinks current. Both switches are connected to a piezoelectric wafer.
When the wafer is tapped, the switches are activated.
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Power Reminder Beeper
This circuit produces a short beep once each minute. It is powered directly off the
120vac power line to remind you that a device connected to the circuit is turned on.
It is simple enough to be packaged inside a small plastic box. It might be ideal for
computers, printers or some test equipment that shouldn't be left on all night.
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- Service Beeper:
This device functions like a lobby desk service request bell. A short beep is
sounded whenever the large pushbutton on top of the device is pressed. Once
pressed, the device will not make another beep until at least 2 minutes of time has
elapsed. This prevents impatient customers from ringing the bell over and
over.
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- 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 ....
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Very Loud Piezoelectric Beeper Circuit
This circuit is similar to circuit number 7, but generates a continuous tone
instead of a pulsing one. The circuit delivers about 110db (12 inches away) from a
9v battery using a single inexpensive C-MOS IC. An off-the-shelf piezoelectric
beeping device is driven at resonance to insure maximum efficiency.
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