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I'm going to buy some IR sensors for gas detection measure. As soon as I need lights on specific waves length for measure specific gas, I have opted for a black body IR emitter, specifically this one

I've understood that this type of emitter uses a resistive element connected between two pins.

My questions is that I can't understand how to make it operate. As soon as there are three pins, I can't understand how to connect it to the power supply.

On the datasheet I've read that to

ensure that anytime RH does not exceed the representative limit as shown in this diagram with respect to these conditions: a. f ≥ 5 Hz b. on-time (pulse duration) ≥ 8 ms

Does it mean I need to use a PWM modulation, with a microcontroller (Arduino) for example?

NicoCaldo
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  • Not an expert on these things, but as I read the datasheet, you **must** provide a pulse signal of at least 5Hz. – JRE Jul 18 '19 at 13:17
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    I don't think you want PWM, but rather simply pulsed operation. – JRE Jul 18 '19 at 13:18

2 Answers2

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This device is intended to be used with the heater current modulated, generally by a square wave. This allows the system to analyze the received radiation as an AC signal and eliminate DC effects such as drift. More traditional systems use a chopper wheel to do the same thing.

In order to avoid overheating the resistive element (the membrane), the note implies that during the on-portion of the excitation, you will monitor both applied voltage and current. From this you can calculate the resistance, and from the resistance you can infer the temperature. So it's up to you to do these things.

WhatRoughBeast
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  • So I think I will need a square wave generator and a potentiometer with whom regulate the resistance to keep the right operational temperature. Is it right? – NicoCaldo Jul 18 '19 at 14:05
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In terms of your actual question, the connection diagram on the datasheet seems perfectly clear to me: the heating element is connected between two of the pins, and the third pin is simply for grounding the case.

Dave Tweed
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