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Topic: Reverse Polarity with Photoresistors (Read 1 time) previous topic - next topic


So I had this brilliant idea...

Say I have a small DC motor.  One positive and one negative terminal.  Lets say this DC motor can move a toy car forwards and backwards, based on whether I flip-flop negative and positive or not.

Is there anyway to wire positive and negative to photoresistors in such a way that the toy will "chase" light?  So if I have a couple photoresistors on the the front of the toy and shine a my light at it...it goes forward.   Likewise, if I shine a light on the back, it goes backwards.

Purpose:  A photovoric self-feeding little car.  That moves towards the light.

I tried to wire up a circuit on my breadboard with some photoresistors and diodes.  My thought was that electricity would follow the path of least resistance...aka, the brightest path in this case.  But after about ten arrangements of diodes and resistors and wires....I couldn't encourage the DC motor to move AT ALL.  My power source is sufficient 10v for a 4.5 volt motor.  I CAN get the motor to move on a simple circuit with the resistors all working in parallel.  So I know my components are working.

The way I have it wired has my positive battery terminal splitting in two  ---<  Both branches have TWO photoresistors.  Those then lead into one of the two terminals (with a diode) on the motor.  So I have each terminal of the motor being fed positive, essentially.  I also connected each side to ground, through another diode and photo resistor.

I don't understand why it doesn't work!!!  When I place two LED's in the circuit (reversed from each other) it works exactly right!  One set of photoresistors will power the green LED, and the other powers the red.  With no light, nothing moves.  With light only on one side, only one LED turns on.

I'm baffled.  The only thing I can think of is that I need less resistance and/or more power.  Any ideas?
"I'll save you!"  (Promptly dies)



This is a site for exactly what your talking about, no arduino even needed. This is called BEAM robotics. Iv done a many projects in it. This should explain all your wanting to know. If there is some thing you don't understand, then just message me.


Cross posting is one way to really annoy members on this site. Please don't do it.

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