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Hot-shoe signal to external GPS

Started Apr 24, 2017 | Questions thread
BobORama
BobORama Senior Member • Posts: 2,842
Re: Hot-shoe signal to external GPS

Hi,

You can implement an edge triggered debouncing circuit. It will activate on the rising edge and the output will stay logic high until a certain time elapses. I am quickly cribbing from the Internet, and this diagram has more than you actually need:

See http://www.talkingelectronics.com/projects/100%20IC%20Circuits/1-100_IC-Ccts.html

The left most pair of NAND gates acts as a debouncing circuit / latch which will set pin 3 logic high for a predetermined amount of time when the leading edge of the input to pin 1 is detected.

The right hand pair of NAND gates forms an square wave generator for driving the speaker.   Unless you need an audible alarm when the shutter goes off - you can skip that and the transistors

So no matter how short the duration of the input pulse, the output from Pin 3 will stay high for as long as indicated by the R-C circuit in between the two left most gates. So for, say, a 100ms pulse you would want 1 microfarad and a 10K resistor?  Or a small potentiometer so you can adjust it later.

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