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March 2017

Laser Flashing

I need help with a circuit design to flash a 10W laser diode at 14 Hz. A crystal controlled 555 IC is too variable due to temperature, and must be calibrated. No microcontrollers please; too complex and require coding. I need a simple discrete design.

The problem is laser diodes are pulsed with a tiny duty cycle, so they must be pulsed at high PRF to create the 1/28 second ON cycle. Probably 100 kHz for 1/28 second, off for 1/28 second, repeat ... It may require multiple laser diodes, interleaved ON pulses to smooth out the 14 Hz ON cycle. I basically want to emulate as close as possible the 14 Hz square wave. To top it off, this needs to run off the “dirty” rectified 6-12 VDC from a motorcycle alternator.

As an alternative, instead of laser diodes, an array of LEDs, perhaps 6 x 6 (36 LEDs) may be acceptable to simplify down to just a 14 Hz crystal controlled strobe timer.

The whole thing needs to fit in a garage door opener sized box.

#3173
Tom Uryga
Hillsboro, OR

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