• 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.

• 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.

• MACHINE VIBRATION TRIGGERS HOUR METER
  This circuit allows an off-the-shelf battery powered digital hour meter to be turned on and off, according to a machine's operation, without requiring a direct electrical connection to the machine. Machine vibrations are detected by an off-the-shelf piezoelectric wafer. The wafer is normally used as a sound generator. The 3v power could be tapped from the hour meter's own lithium battery or from a separate 3v lithium battery. The circuit only draws about 1.5uA, so a 250mA-hr battery would power the circuit for about 10 years. Published in EDN, Jan 16, 1997

• Motion Alarm
  Using a piezoelectric device, this circuit will activate a beeper whenever the circuit is moved.  It could be used as an earthquake alarm.

• Motion Alarm Using Piezoelectric Device
  An inexpensive piezoelectric device is used as a motion sensing device for this motion alarm. This circuit will activate a beeper whenever the circuit is moved.  It could be used as an earthquake alarm.  (added 7/06)

• 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.  (added 7/06)

• Piezoelectric Vibration Sensor Activates Switch
  An inexpensive piezoelectric wafer is used to detect vibration and when the vibration is sufficient a switch is activated.  (added 7/06)

• Ultra Low Power 32KHz Crystal Oscillator
  I have used this circuit many times when I needed a low frequency reference, which did not draw much power.  With the components show, the current from a 3v battery is less than 1.2 microamps.

• 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.

3V supply delivers 12V p p to piezo speaker:  10/16/03 EDN Design Ideas  /  (added 1/05)  Low-profile piezoelectric speakers can provide quality sound for portable electronic devices, but y require voltage swings greater than 8V p-p across  speaker element. Yet, most portable devices include only a low-voltage power source, and conventional amplifiers operating from batteries cannot provide enough voltage swing to drive a piezoelectric speaker....

741 Based Light Sensor:  CdS photocell used for light/dark controlled relay (added 5/02)

Amplifier compensates piezoelectric rate gyros:  12/09/99 EDN Design Ideas /  (added 11/05)

Deer Repellent #1:  seismic sensor (added 02/05)

High Voltage Amplifier Drives piezo tubes:  12/07/04 EDN Design Ideas  / (added 1/05)  Piezoelectric tubular positioners that drive manipulators in scanning tunneling microscopes require high-voltage, low-current drive circuits. The circuit in Figure 1 can drive high-resistance, low-capacitance piezoelectric loads at a -3-dB bandwidth of 6 kHz. It offers a low-cost alternative to commercial drivers.

History of Piezoelectricity:  (electronic design / schematic added 2/06)

Introduction to Piezo Tranducers:  (electronic design / schematic added 2/06)

Knock Alarm:  (electronic Circuit / Schematic added 10/04)

Piezo crystal monitors liquid level:  03/30/00 EDN-Design Ideas / (added 11/-5)

Piezo DeviceGenerates 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....

Piezo Devicegenerates buzz beep or chime #2:  05/07/98 EDN-Design Ideas  / (added 11/05) 

Piezo Disk:  (electronic (schematic / circuit added 2/05)

Piezo Education/Tutorial:  (electronic design / schematic added 2/06)

Remote Switch uses No Power Fiber Optic Link:  10/10/96 EDN-Design Ideas / (added 3/03) The heavy-duty switching device in Figure 1 counts the number of products manufactured and rolled out of a production line per hour. The switch is useful for counting rolling heavy objects or materials weighing one to several thousand kilograms. It generates one pulse per product (no false outputs generated) and provides a count rate as high as 3600 parts per hour. The switch uses a low-cost, commercial, piezoelectric gas lighter, commonly used for kitchen or gas-grill burners. A rolling object in the production line triggers the device, and a simple fiber-optic link transmits the ignition event to a receiver.

Shock Sensor Circuit Prevents Data Corruption:  07/04/96 EDN-Design Ideas / (added 3/03)  Hard-disk drives for laptop and other portable applications need to withstand significant g-force shocks when operating. A typical 1.8-in. drive writes servo information over less than 15% of the disk's active area, which means that the read/write head spends more than 85% of the time outside the servo loop's control. A g-force shock during this time could cause the read/write arm and head to move away from the current write track and to permanently write corrupting data on an adjacent track or elsewhere....