|
Circuits designed by David Johnson,
P.E.
Last Updated on:
Tuesday, December 26, 2017 07:05 AM
Master Category List - Dave's Circuits
The contents &
graphics of Discovercircuits.com are copyright protected.
LINKING to Dave's circuits is permitted but DO NOT COPY any files to your WEB
SITE server |
 |
|
|
|
|
|
|
More
Beepers
& Buzzers; Piezoelectric
|
|
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. |
|
| |
 |
|
| |
Pulsating Beeper |
|
|
|
Click on Drawing Below to view PDF version of Schematic |
|
 |
|
|
|
