Re: Using piezoelectric to power a laser diode?

On 26 Jan 2006 18:45:18 -0800, bobrich@xxxxxxxxx wrote:

>Hi,
>
>I'm a complete novice/noob to electronics.
>
>I have a little project i'm working on, and would like to use a
>piezoelectric power source to run a small visible laser diode for a
>short duration (20-200ms). Does this seem feasible? The biggest
>problem, from what i can tell, is the output voltage of the piezo is
>likely to be much greater than the 2-3V i need to run the diode. The
>other problem i'm having is actually finding suppliers of piezo devices
>that would be suitable for this...all i can find are accelerometers and
>strain gauges.
>
>Any thoughts? The energy source will be a sharp blow from a small
>spring-loaded lever.

---
That won't work.

Try this:

Vcc Vcc
| |
[10K] [100K] +-------+
| | |__ |
+------[0.1µF]--+------|--O|TR OUT|O---[R]--+
|- |A | | | |A
[PIEZO] [1N4148] +---|TH | [LASER]
|+ | | |_ | |
GND GND +--O|D | GND
| +-------+
[1.5µF] 555
|
GND

1.5µF will get you a 200ms pulse out of the laser and 0.15µF will
get you 20ms.

Or this:

+-----+
+------|~ +|----+-----+
| | | |+ |A
[PIEZO] | | [C] [LASER]
| | | | |
+------|~ -|----+-----+
+-----+
FWB

You'll have to determine the value of C experimentally. Start with
something like 10µF and work down until the laser flashes.

It worked for me with a plain old red LED and the piezo element from
a barbecue lighter, which you might be able to adapt for your use.



--
John Fields
Professional Circuit Designer
.