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Electronic Buzzer - This very simple circuit just uses a couple of resistors, a
capacitor and the easily available 555 timer IC. The 555 is setup as an astable
multivibrator operating at a frequency of about 1kHz that produces a shrill noise when
switched on. The frequency can be changed by varying the 10K resistor. (added 6/06) |
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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 electronic design
added 2/06) |
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Electronic Chime - Scroll Down to find this circuit. This circuit simulates a
chime similar to the sound many cars make when the keys are left in the ignition. The
bottom two gates form a squarewave audio oscillator that drives the base of the
2N4401, turning it on and off at an audio rate. The top two gates produce a short
low-going pulse about once per second that discharges the 10 uF capacitor through the
diode. The voltage then jumps up and slowly decays .... (electronic design added 6/07) |
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Electronic Police Siren - The sound produced imitates the rise and fall of an
American police siren. When first switched on the 10u capacitors is discharged and
both transistors...(electronic design added 08/08/08) |
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Electronic Siren - An electronic siren made from discrete components. (schematic
added 03/04/05) |
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Emergency Vehicle Car Siren - This siren circuit simulates police, fire or other
emergency sirens that produce an up and down wail. (circuit design added 08/08) |
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Fix Adds Door Chime Repeater - 05/13/99 EDN-Design Ideas:.....(design idea added
70/08/09) |
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Flip Flop Flashers Buzzers Etc - Several circuits here. The familiar astable
flip-flop circuit is a handy configuration for making flashers or generating
squarewaves. Here is a typical alternating LED flasher with the LEDs in the emitters
instead of collectors as is normally done. The bias resistors are directly
connected...(added 04/05/06) |
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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. Posted ….(designed by David A. Johnson) |
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Harvest energy using a piezoelectric buzzer - 03/20/08 EDN-Design Ideas: You can
harvest small amounts of mechanical energy using a piezoelectric buzzer to charge a
supercapacitor.....(design idea added 09/08) |
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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
….(designed by David A. Johnson) |
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Inexpensive LED Drives Flash & Beep Circuit - 06/05/97 EDN-Design Ideas: (design
idea added 4/02) |
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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.
….(designed by David A. Johnson) |
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Multi-Switch Doorbell with Indicators - (electronic Circuit / Schematic added
10/04) |
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One IC 2 Tones Siren Double Tone Police Sound Single Tone Old Ambulance Sound -
This circuit is intended for children fun, and is suitable to be installed on
bicycles, battery powered cars and motorcycles, but also in models and other games.
With SW1 positioned as shown in the circuit diagram it reproduces the typical dual
tone sound of Police ....(added 9/04) |
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Personal Alarm redcircuits - Small portable, anti-bag-snatching unit. Also
suitable for Doors and windows control (added 9/04) |
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Piezo device generates buzz beep or chime - 05/07/98 EDN-Design Ideas: (design
idea added 6/06) |
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Piezo DeviceGenerates Buzz Beep or Chime - 04/23/98 EDN-Design Ideas: (design
idea added 05/03) |
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Piezoelectric driver finds buzzer’s resonant frequency - 08/07/08 EDN-Design
Ideas: By driving a piezoelectric buzzer near its resonant frequency and counting the
residual oscillations, a microcontroller can find the buzzer's resonant
frequency.....(design idea added 09/08) |
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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.
….(designed by David A. Johnson) |
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Piezoelectric Vibration Sensor Activates Switch - An inexpensive piezoelectric
wafer is used to detect vibration and when the vibration is sufficient a switch is
activated. ….(designed by David A. Johnson) |
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Police Car Siren - This siren circuit simulates police, fire or other emergency
sirens that produce an up and down wail. (circuit design added 08/08) |
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Power Reminder Beeper - This hobby electronic 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. ….(designed by David A. Johnson) |
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Powerful Siren - Simple circuitry No ICs 12V Battery operation (added 9/04) |
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Pushbutton Activated Service Request Beeper - A single press of a pushbutton
switch turns on a beeper for one second but can’t be activated again for 60 seconds.
(added 7/06) ….(designed by David A. Johnson) |
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Red Alert Star Trek Alarm - Scroll down to locate this circuit. The third circuit
simulates the "Red Alert" siren from the TV show Star Trek. It uses two 555 timers in
the circuit. The 555 on the right is wired as an alarm tone generator and the second
555 timer on the left is wired as a 1.5 second non-symmetrical....(electronic design
added 6/07) |
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Remarkable R-Beeper-by Tom Bruhns - (circuit added 07/07/07) |
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Remote Doorbell Indicator - (electronic schematic / circuit added 4/02) |
