Posted by cognoscis on May 1, 2008
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Sensors – LDR
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This entry was posted on May 1, 2008 at 4:08 am and is filed under Robotics.
Tagged: LDR, sensors. You can follow any responses to this entry through the RSS 2.0 feed.
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IR sensors « Cognoscis’s Weblog said
[...] Cognoscis’s Weblog Just another WordPress.com weblog « Sensor - LDR [...]
joe said
Absolutely love your technique! Surprised I didn’t come across your blog earlier! Thanks for sharing and keep writing!
tinus said
Hey,I’m after a LDR that can work with 3V only. Is there anything on the market? thanks guys.
cognoscis said
HI,
LDR is just a resistor, so whatever voltage you apply, it will work well… You can try the normal one you have and if it doesnt work, you can get back to me
Sanjana Sharma said
Hey,
I need ur help as early as possible…In order to convert the LDR output to digital we r using an analog to digital convertor…bt den on connecting it to d adc d ic is getting burnt..can u tell d reason for it…
cognoscis said
Sanjana,
The reason for that happening is obviously over current. As I have mentioned before, LDR is just a resistor. When light falls on it, its resistance will become almost zero and hence a lot of current will flow into the ADC. But, this problem might also be due to incorrect biasing. place a 10kΩ potentiometer in series to that LDR input that goes into your ADC. Initially keep it at maximum and see if your IC heats up. If it does, then probably you must cross check your circuit for any places where there might be short circuit. Else, slowly reduce its resistance till you get proper output from the ADC.
If you are using ADC because you want EXACT value of the current coming into the circuit then its OK. If you are using ADC only to convert your AC to DC, then I suggest you switch to the simple comparator that I have shown in this post. All the same, if you can provide your circuit diagram and the part number of the ADC then I can try to pin point the bug in your circuit
Sanjana Sharma said
Hey,
Actually we got d circuit made from sum1….now dat person is saying that drs no problem in d ADC..its d OP07 which is getting burnt on connecting to ADC….what mite be d reason here?We have our project submission 2mrw…n sumthing or d odr gets spoilt every now n then..plz sort this out…..if possible you can send me ur email id..will directly contact u via messenger
How to make a PCB at home « Cognoscis said
[...] IR signal for modulated IR sensor explained in my previous post. The second picture is a part of LDR sensors I made for my line follower robot. The picture has a comparator circuit and a motor driver circuit [...]