Author Topic: problem with analog sensor assembly  (Read 1024 times)

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Offline mohit sharmaTopic starter

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problem with analog sensor assembly
« on: February 03, 2010, 08:46:06 AM »
i have tried the sensor circuit shown but cant get change in output voltage when photodiode receives infrared signals plz help me to find out any error or any other simple analog sensor circuit.

Offline little-c

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Re: problem with analog sensor assembly
« Reply #1 on: February 03, 2010, 02:25:38 PM »
the drawring on c1 is a bit dodgy, but other than that its a pretty good circuit.

just,( http://www.societyofrobots.com/schematics_infraredemitdet.shtml ) photodiodes may not be sensitive to IR. depends on how they are built.

on the up side, its a very good circuit.

Offline Razor Concepts

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Re: problem with analog sensor assembly
« Reply #2 on: February 03, 2010, 02:40:16 PM »
The photodiode in your circuit is put the wrong way.

Offline mohit sharmaTopic starter

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Re: problem with analog sensor assembly
« Reply #3 on: February 04, 2010, 11:26:23 PM »
hey i have read the tutorial given on this site . My photodiode resistance is about 1500k ohm i have connected a 2000kk ohm resistance bt it is still not working plz help me in the sensors assembly.

Offline Pratheek

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Re: problem with analog sensor assembly
« Reply #4 on: February 05, 2010, 01:28:49 AM »
This is circuit, I presume, is built to be interfaced to a microcontroller by ADC.

Can you tell me how you came to the conclusion that you are not getting a proper output - did you use ADC of a microcontroller or use a multimeter ?

And also did you keep the PORTC pin3 on continuously?





Offline mohit sharmaTopic starter

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Re: problem with analog sensor assembly
« Reply #5 on: February 07, 2010, 07:26:25 AM »
sir i have read that if ir rays falls on photodiode then there is change in voltage .
There will be voltage around 1v bt when light falls it begin to conduct & the voltage will be around 5v this is not happening with me in this circuit if i am wrong then plz correct me & tell me any other method to check whether it is wrking or not.

Offline Soeren

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Re: problem with analog sensor assembly
« Reply #6 on: February 07, 2010, 05:54:23 PM »
Hi

It's allways a good idea to write what you have measured and where. Remember, this might be crucial information in the search for an answer.

sir i have read that if ir rays falls on photodiode then there is change in voltage .
When light falls on it, it will allow a larger flow of electrons.


There will be voltage around 1v bt when light falls it begin to conduct & the voltage will be around 5v this is not happening with me in this circuit if i am wrong then plz correct me & tell me any other method to check whether it is wrking or not.
Your circuit is not for what I think you wanna do. If you're trying to measure with a DMM on the output (marked "To ADC0"), you'll get 0V on DC, light or not, as DC and slow changes won't register as you have it coupled through a capacitor (C2).

If you measure on the other side of C2, what happens then?
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

 


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