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Circuits designed by David Johnson, P.E.
Last Updated on: Thursday, April 07, 2016 02:04 PM

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Beeper & Buzzer Circuits
Beeper & Buzzer Circuits Designed by Dave Johnson, P.E. :
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24V DC Powered Beeper with 4 Separate Inputs  -  24vac is a popular voltage.  It is often used in low voltage lighting systems and industrial controls.  It is much less dangerous than 120vac/240vac line voltages.  This hobby circuit below is one method to efficiently power a cluster of 7 white LEDs from 24vac. . . . [Hobby Circuit designed by Dave Johnson P.E.,  12/19/09]


3v Powered Loud Beeper  -  Getting a high sound intensity from a piezoelectric type beeper is not easy when the available DC supply is only 3v.  The circuit below is not only efficient but produces a very intense sound.  The circuit combines a voltage boost section with a resonant  . . . [Circuit by David A. Johnson P.E.,  02/18/09]

3v Sweeping Siren Alarm  -  A while back I was challenged by a visitor to the website.  He needed a very loud sweeping siren type audio sound generator powered by 3v.  He tried some of the commercial sirens but they were not very loud when powered by 3v.  He also said that those . . . [Circuit by David Johnson P.E.,  06/24/08]


AC Power Loss Alarm  -  I’ve been having a problem with my instant hot water system lately.  This system circulates electrically heated water throughout my house using a small pump.  The pump is wired into a ground fault interrupter (GFI) module.  Every now and then, the GFI trips, leaving me without hot water . . . [Circuit by David Johnson P.E.,  03/29/09]


Alarm Beeps when the “Check Engine” Light Turns On  -  When wired into a car’s indicator light panel, this circuit will turn on a loud beeper when the “check engine” light turns on . . . [Circuit by David A. Johnson P.E.,  07/09/06]


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 piezo device to more than 200 volts peak to peak . . . [Circuit by Dave Johnson P.E.,  06/27/00]


Appliance Unplugged Alarm  -  I received a call from an administrator at a large prison.  He told me that he was having problems with inmates who keep unplugging refrigerators, vending machines and microwave ovens in a commons area.  He wanted a battery-powered device, which could be mounted to the outside of the power cord of an appliance. . . . [Hobby Circuit designed by David A. Johnson P.E.,  04/25/10]


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 . . . [Circuit by Dave Johnson P.E.,  06/04/00]


Basement Remote Doorbell  -  This circuit will activate a beeper alarm whenever the AC line voltage is less than 100vac . . . [Hobby Circuit designed by David Johnson P.E.,  07/11/06]


Beeper indicats Check Engine  -  When driving down a busy road, you may not notice a “check engine” indicator light that suddenly turns on within the car’s instrument panel.  You could drive for many miles before noticing the light.  To provide an audible indication of trouble, the hobby . . . [Hobby Circuit designed by David Johnson P.E.,  07/09/06]


Beeper that is Very Loud  -  This circuit 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 maxim . . . [Circuit by David Johnson P.E.,  06/03/00]


Beeper & Buzzer Circuits Designed by Dave Johnson, P.E. :
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