analog signal from smoke detector

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1

Hey guys,

I am trying to read the analog signal (of smoke detected in the smoke chamber via photo diode) in a commercial smoke detector. I am trying to read this signal into Arduino and compare with a standard particle counter.

The commercial smoke detector is,

Name: First Alert

Model No : P900E

It uses a MicroCHIP IC RE46C145 and I think I might have to connect to one of the channel in the CHIP, but I am not sure which would be correct channel to use.

Here is the manual for this model, http://www.firstalertstore.com/store/im … manual.pdf

2

Pin 3 of the IC. You can look at the pinout in the IC datasheet. http://www.farnell.com/datasheets/1669456.pdf

Chances are the detector is operating from a 9V battery, which means that if you want to connect it to an Arduino that is operating at 5V, you will need to bring that 9V signal down to a 5V signal that the Arduino can handle. You can try a voltage divider (http://www.raltron.com/cust/tools/voltage_divider.asp) or get a logic level shifter from Sparkfun.