-
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 Vibration
Controls 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 Tap Switch
This circuit uses a flat piezoelectric wafer, glued inside a plastic box, as a
finger tap sensor. With each tap of a finger to the box holding the wafer, the
circuit turns on and off AC or DC power to an external device. The circuit is
powered by a 9v battery and drives a single coil 5v latching relay with a 10 amp
contact rating. The relay can switch AC or DC power. In standby mode the
circuit draws a low 1ua
|
-
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.
|
|
|
-
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 3v
Powered 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 feedback network. The voltage applied to the piezoelectric
wafer is about 40 volts peak to peak. The result is a circuit that generates
an attention getting sound without drawing a lot of current.
|
-
Very
Loud Beeper Circuit
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 maximum efficiency.
|
-
Very Loud
Piezoelectric Beeper Circuit
This circuit generates a continuous tone instead of a pulsing one for your hobby
project. As seen in the schematic, the hobby circuit delivers about 110db (12 inches
away) from a 9v to 12v source using a single inexpensive C-MOS IC.
|
-
Very
Loud Pulsating Beeper Keeps Average DC Current Draw Low
Many battery powered alarms draw excessive current when operating. Some of the
most attention-getting noise makers, such as the unit shown below, use piezoelectric
sound generators with a frequency sweeping tone. When operating with a 9v
battery, these units can often draw 100ma or more. In many applications, a
continuous alarm sound is not needed. Locating a balloon or a rocket are
examples where you want a loud sound but a low average power drain. To lower
the average current, the device can be pulsed with short 0.05 second chirps, once
every two or three seconds. This lowers the average current by a factor of 60.
So, instead of drawing 100ma, by chirping the alarm, the current is lowered to just
2ma. The circuit below generates the pulse train needed for these short but
very loud chirp sounds.
|
