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pyrometer


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i want to make pyrometer signal conditioning system using photodiode or phototransistor, but i've got so many problems, coz my photodiode and phototransistor still cannot detect infrared that radiated from an object at certain temperature.

i've try combinate the circuit with current amplifier but it doesn't work, it just can detect light well, not infrared radiation from an object.

i tried use a film that cover the sensor to filter the incandescent light, it works, but still cannot detect infrared.

i hope anyone can help me, thanx b4.

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i,m not sure about the measurement range of my sensors photodiode/phototransistor(pd/pt) ??? coz there are no serial number on it. so i'm not sure that my pd and pt can detect both IR and light, or only light except i tried it by myself.

i've tried some pd and pt (black pd, white pd, gold pd, silver pt, and 2 pin pt) but i do not know why those sensors cannot make change of output when i gave them heat source, but when i gave a source of light they can make change of output very well.

i want my pyrometer at least can detect around 10 degree celcius change temp from the ambient temp with 5 - 10 cm long distance from the object that will be detected.

here are my schematics i've ever made:
using 1 black photodiode;

using 2 white photodiode (1 pd for detecting source signal and noise & another for noise);

and 1 phototransistor;

untill now i'm still assumed that those sensors can detect infrared that emited from an object, so i hope there's a better treatment or circuit to gain the output of sensors.

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I don't know why you have two photo-diodes in your 2nd circuit. Their outputs cancel.

1) In your 1st circuit, R1, R2 and R3 are not required.
2) The photo-diode doesn't have a load which should be a 100k resistor to ground.
3) The two transistors are also not required since the photo-diode and its load resistor can connect directly to the non-inverting input of a high gain opamp circuit.
4) The 200 ohm R4 feedback resistor has its value far too low. Opamps don't have enough output current for a resistance so low. Your 1st opamp is an inverter with a very low gain and a low input impedance. It should be a non-inverting opamp circuit with a high gain and a high input impedance.
5) Your 2nd opamp is also an inverter without any gain. Its gain is only 1.

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In my circuit I used a 100k resistor as the load for the photo-diode. Without light or IR, then the input voltage to the opamp through the 100k resistor is 0V.

I used a non-inverting opamp circuit with the extremely high input impedance of the FET in the input of the opamp, and it has voltage gain of 1001 to 10,001. You might need to use a TL081 single opamp so that you can add an offset voltage adjustment.

Please make schematics in a GIF or PNG file type. JPG file type is for photographs and modifying a schematic with it makes it very fuzzy.

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You are trying to detect IR. IR is produced by heat. Guess what is 90% of the energy emitted by an incandescent lght? Hint: hold the light bulb in your hand.:D
Hint again: Isn't sunlight bright and hot?

IR photodiodes and photo-transistors are available in a black package that filters out visible light pretty well.

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so do you mean that my black photodiode and a film is good enough to eliminate noise from light?.

and my sensor is good to detect IR that come from object surrounded the sensor and the lamp itself, even from sunlight (carry light and IR)?

so what i need now is to focus my sensor to an object that will be measured, is'n it? 

are there any suggestion to focus my sensor to detect the IR signal just from an object that will be measured without interfered by IR from another object?

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