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Hello,
I tried searching for discussion concerning this topic but I found nothing, so I decided to make a new topic.
I need a sensor that can distinguish basic colored lights, like blue or red, and I built a circuit following the "Color distinguished using LDR/Color sensor using LDR" circuit diagram (http://www.engineersgarage.com/electronic-circuits/color-sensor-using-ldr), but I haven't been able to get it to work properly and I am a bit confused about the whole diagram as well.
There are two LEDs, one is the output LED that supposedly shows whether your light is the same as the reference voltage has been calibrated to, but what is the other one for? And what is the point of connecting the LDR and LED both to the negative input of the IC?
The circuit I have now only shines the LED connected with R3 all the time, and the other LEDs brightness can be controlled via VR2, which is not what it's supposed to do I reckon.
I hope someone can tell me what I've done wrong.
– Bob
Hi bobby,
In two LED's one which is connected to the R3 resistance is power LED it is to indicate whether the circuit is powered or not. And LDR and LED is not connected to the negative input of LM324. only LDR output is connected to the 7th pin of LM324 and led is connected to the Ground not with ldr and 7th pin of LM324.
Hi Prabakaran!
Thank you very much for your answer! The circuit diagram does not clearly state whether the power LED is connected to the 6th pin, so that was very helpful.
I still can't get it to work though, and I don't know where the problem lies. I have used 5k potentiometers instead of 10k, so that could contribute to it, but I doubt it. I have no clue if it is the soldering, a broken component or just an error in circuit building. Guess I'll keep working on it..
– Bob
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