Newbie with photoresistor problem
The following is a very simple circuit that uses a photoresistor as a switch to run a motor using a battery pack. But for some reason no matter how much light i expose the photoresistor to it does no conduct. The general resistance without any light is 200, 000 ohm. and using a torch it is 440 ohm. HELP.
Last edited by Karthik; - 13th August 2008 at 20:02.
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Most assuredly NOT the way to run a motor using a photoresistor. Sounds real good in theory for somebody that doesn't know any better, but still, not the way to do it.Originally Posted by Karthik
You might be wanting to use a phototransistor to do this job. But again, not the best way to do the job.
And how does this tie in to PicBasic?
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LDR is a SENSOR - not a controller
The Light Dependent Resistor is a sensor. Its resistance is way too high to drive any conventional low cost motor. In darkness the LDR will be several megohms. In bright light it will be under 1000 ohms, depending on make and model.
You need to measure the LDR with either the POT command or an ADC and then convert that to a PWM signal to drive the motor.
HTH
BrianT
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Here is a sample circuit to drive a dc motor with a(n) LDR.
Works in simulation at least!
<img src="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=2817&stc=1&d=121878587 6" >
"If the Earth were a single state, Istanbul would be its capital." Napoleon Bonaparte
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Seems to work in reverse
Sayzer, thanks for posting the schematic.
I too need to turn on a motor with a LDR, however, when I made the circuit as diagramed, it works in reverse. It turns the motor on in light, and off in darkness.
Does anyone know what do I need to do to make the motor turn on in darkness, and off in light?
thanks
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Flip LDR and R1???
Dave
Always wear safety glasses while programming.
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Re: Seems to work in reverse
How much voltage do I apply for running that motor?
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