Help! My infrared light meter needs a home!

Tbag

Hey folks/tech support, I have what appears to be a simple issue I need some help on, please.

I have a breadboard infrared light meter. I wish to hook it up to my Basic Stamp 2 and record the voltage outputs over time on my PC. Of course, I will build the circuit on the Stamp breadboard.

The circuit designer advised me to "Connect the + of the output to the + input of the PIC. Connect the shield output of the circuit to the - input of the PIC. To the PIC the signal will start at zero volts and increase with light intensity." - a quote.

My (+) output is from PIN 6 of my L411 Op-Amp.
My negative is a lead from the shield circuit he has just described at a regulated 2.5 V.

1. To what part of my Stamp do I connect each?
2. What program can I use to record the voltages? ( I assume that Stamp Lite will only work with phototransistors).



Mr.Tbag

Post Edited (Tbag) : 4/15/2005 6:13:18 PM GMT

Newzed

You can not connect the output leads of your device directly to a Stamp pin.· The output needs to go to an ADC, and then the output of the ADC conn4ects to the Stamp.· When he is talking about connecting to a PIC, he is saying connect to one of the PIC pins that is an ADC input.

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Tbag

I have an ADC 0831 - will that do?

If so, can you tell walk me through the connection between my circuit and the ADC and the ADC and the Stamp 2? The ADC 0831 is ubiquitous I think, but I can post/send the specs with PIN numbers if this can help you.

Thanks very much

Mr.Tbag

allanlane5

Download the "digital and Analog Interfacing" class from Parallax. It has a full 0831 example in it.

Tbag

Ok, folks, sounds like a plan.

Part 2 - what would be your personal preference if you were making an IR light meter - a photodiode or a phototransistor?

Posts very much appreciated

Tbag