- 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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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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- 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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- 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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- 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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