# piezo transducer; polarity; current

Discussion in 'Electronic Basics' started by Adam Funk, Mar 21, 2012.

I've been playing with a piezo transducer in 556 circuits (at higher
frequencies than with LEDs). The one I'm using is KPE-163, and the
specification says:

Rated Voltage (Vp-p) Max 30
Current Consumption (mA) Max. 10 @10Vp-p, square wave, 4.8Hz

and it has two leads: one black and one red.

I was wondering whether it would work in a double-555 multivibrator
(powered by a 9V battery) described as having push-pull output, and it
does (I think I had some resistance in series just to be careful). So
I wondered whether the implied polarity in the lead colors was
significant.

AFAICT from trying it turned both ways in a single-555 multivibrator
(between the ground and 9V square wave output), I suspect it isn't

Also, does the specification mean that the actual current when you
apply 10Vp-p voltage is 10 mA, so (unlike LEDs, for example) it
doesn't need any protective series resistance at that voltage?

(I have 5 of these and they were cheap, so I don't mind burning a
couple out for educational purposes.)

2. ### Phil AllisonGuest

** That is a piezo buzzer - it has an electronic circuit that makes the
beep.

** Beep, beep beep beep .....

3. ### Jasen BettsGuest

is it this one?
http://www.datasheets.org.uk/indexdl/Datasheet-077/DSAE0052603.pdf
another reason to colour the leads is that if you have two and want the
both to be in phase you can match the leads up
Phil H says thet y can be damaged by prolonged exposue to reverse
polarity. Phil A seems to have the part confused with a different part.
that's right. it doesn't need any. these devices behave like lossy
capacitors each time they get a voltage change they will only accept a
small amount of charge
with the 556 you can make a louder noise by using a bridged
configuration:

. . . . . . . .
.O . . .
[. . . .]--+
. . |
. . |
+--------[. .] |
C1 | . . |
|| | . . |
+--||--+ [. 556 .]-----+
| || | . . | |
| | . . | |
| +-----------[. .] | |
| | | . . | |
| | +-[R1]-+ . . | +-----
| | | +-[. .]--+ |
| | | | . . | | to piezo
| | | | . . | |
| | +------|-[. .]-----------
| | | . . | |
| | | . . | |
+---------------[. .]--|--+
| | | . . | |
| | | . . . . . . . . | |
| | | | |
| | +--------------------|--+
| | |
o o------------------------------+
- +
9V battery

or you can produce a varying tone by driving the CV pin
of the cecond astable from the first.

+---------------------------------.
| |
|+ . . . . . . . . |
===== .O . . . |
| C1 [. . . .]---+ |
| . . | |
| . . | |
+--------[. .] | |
| . . | |
| . . | |
| [. 556 .]-----+ |
| . . | | |
| . . | | |
+-----------[. .]--------+
| | . . | |
| | . . | |
| +--[R1]--[. .]--+ |
| | . . | |
| | . . | |
| +--------[. .]--------------+
| . . | | |
| . . | | |
+---------------[. .]--|--+-+-[R2]-+--- +
| | . . | |
| | . . . . . . . . | ===== to piezo
| | | C2 |
| +------------------------------+ +-----------
| | |
+---------------------------------------+
| |
o o
- +
9V battery

R1 47K
C1 10uF
R2 3.3K
C2 10nF

I expect that will make a horrible racket.

4. ### Phil AllisonGuest

"John Fields"
"Phil Allison"

** See the OP's post.

" Current Consumption (mA) Max. 10 @10Vp-p, square wave, 4.8Hz "

That error PLUS the pic and description fitted an electronic buzzer.

..... Phil

I think so. The data sheet I have is only in English and just has the
information corresponding to parts B, C, & D in that example.
Oh, that's given me an interesting idea to play with.

Thanks for the other information and suggestions!

Interesting, thanks.

8. ### Phil AllisonGuest

"John Fields"
"Phil Allison"
** Irrelevant.

I found a pic and an ambiguous description.

Did you SEE the error in the OP's post at all ??

...... Phil

What was my error? (The RS website calls it a "Piezo electric
transducer", and the specs were all copied & pasted from the data
sheet.)

10. ### ehsjrGuest

There's a difference in the specs between the datasheet at
the link John Fields posted and the spec you posted:
Your post says "square wave, 4.8Hz"
Datasheet says "square wave, 4.8KHz"

Ed