• 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.

• 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

• 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.

• 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.

• Piezoelectric Vibration Sensor Activates Switch
  An inexpensive piezoelectric wafer is used to detect vibration and when the vibration is sufficient a switch is activated.

• 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.

• 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)

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)

Electronic Canary (Doorbell):  This circuit is a modified "Hartley Oscillator" with a couple extra parts.  T1, the LT700 (or equivalent, is a small center tapped (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 (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... (added 2/06)

Electronic Siren #1:  (electronic circuit added 7/03)

Electronic Siren #2:  (electronic circuit (added 10/03)

Electronic Whistle:  (electronic circuit (added 10/03)

Fix Adds Door-Chime Repeater:  05/13/99 EDN-Design Ideas / (added 11/05)

Flip Flop Flashers Buzzers Etc.:  (circuit / schematic design added 6/06)

Piezo Device Generates Buzz Beep or Chime :  04/23/98 EDN-Design Ideas  /  (added 05/03) 04/23/98 EDN-Design Ideas / (added 11/05) [Note:  File contains multiple circuits scroll to find this circuit.]  Piezoelectric buzzers, such as the Murata (Smyrna, GA) PKB5-3A in Figure 1, make excellent alarms. They're compact, lightweight, efficient, and reliable. However, a piezo alarm is a dc device; it requires additional circuitry to operate from an ac source. The circuits in Figure 1 provide a simple and inexpensive way to obtain the dc drive. The W04G full-wave bridge rectifier produces a full-wave dc waveform from the 120V ac line. The 100 ohm resistor protects the circuit from surges when you first apply power. The 5.5V 1N4733 Zener diode protects the buzzer against high-voltage excursions. The 1-µF capacitor provides filtering for the buzzer....

Plane Locator Beeper #2:  (schematic / circuit design added 9/02)

Plane Locator Beeper:  (schematic / circuit design added 9/02)

Powerful Siren:  Simple circuitry No ICs 12V Battery operation (added 9/04)

Remarkable R Beeper:  (electronic circuit added 7/03)

Remote Doorbell Indicator:  (electronic (schematic / circuit added 4/02)