Counting AC/DC Pulses

mhammer

hello All,


I am researching a new project and am having problems finding a device that i can interface with a stamp to count pulses from both an AC and DC Signal. I looked into a optocoupler but couldn't find any info on them working on a DC current.

The object of the project is to count the number of pulse from a system in a given time. the line that i will be monitoring are both 12 volt dc or 24 volt ac depending on the unit so i need something that will work for both.

does anyone have any ideas?


Thanks


Mike

stamptrol

Mike,

There are a great number of optos that can handle AC or DC whether on the input or the output side. The Digikey online catalog is a good place to start.

On the input side, its usually only a case of choosing the right current limiting resistor.

In your case the output side should be a transistor which makes it easy to tie to the Stamp.

One solution is to use a common optocoupler with a DC LED on the input. Put a small diode around the LED in reverse connection. With the proper resistor in place, now you can apply either DC or AC to the input and see pulses at the output.

Note that if you're applying AC, the stamp will see a train of pulses due to the rectified AC waveform. You can compensate by taking that into account, or if its not necessary to count waveform pulses, just filter the input to the stamp so it stays on anytime the opto input is active.

Cheers,

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Tom Sisk

http://www.siskconsult.com
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JonnyMac

Mike,

The H11AA1 will work for your application. It's a bi-directional opto-coupler.

mhammer

Thanks guys for the help in the right direction. i will research them and hopefully find a solution that will work.


Mike