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Help with Mini Photocell

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Sceadwian

Banned
With wire...? Not sure what your question here is, how do you intend to hook the CDS photo cell up to the LED?
 

SPDCHK

Member
I too cannot understand what exactly it is that you want :confused:

Firstly, I personally always thought a “Photocell” is the same as a solar panel cell (something that generates a voltage proportional to sunlight exposed to the cell). What you list here as a ”Mini Photocell” is what I know as a LDR (Light dependant resistor). Just clarify that for me, is this an LDR as I know it, or a solar cell??

Secondly, if it is an LDR, do you want it switch on the LED (using a 3V battery) when it becomes dark, or do you want a circuit that uses a “Solar Cell” to charge a 3V battery?
 

Sceadwian

Banned
LDR/photocell same thing. The term photocell is falling out of favor for CDS LDR's because of said possible confusion with 'real' photocells but it's been used for a very long time. If you read older electronics books or browse circuits on the web you'll see LDRs called photocells many times. It's definitly an LDR the squigly S of the LDR material is very distiguishing.
 

NGBEnt

New Member
I too cannot understand what exactly it is that you want :confused:

Firstly, I personally always thought a “Photocell” is the same as a solar panel cell (something that generates a voltage proportional to sunlight exposed to the cell). What you list here as a ”Mini Photocell” is what I know as a LDR (Light dependant resistor). Just clarify that for me, is this an LDR as I know it, or a solar cell??

Secondly, if it is an LDR, do you want it switch on the LED (using a 3V battery) when it becomes dark, or do you want a circuit that uses a “Solar Cell” to charge a 3V battery?
SPDCHECK, this is an LDR. I am sorry for the mix-up. So what I want to do is like you said, using wire to switch on the LED when it becomes dark. Does this take the same role as a resistor would if it were used?
 

Sceadwian

Banned
No, a current limiting resistor still needs to be used, LDR's can go to VERY low resistance if a bright light is shined on it. Simply putting the LDR in series with the normal current limiting resistor and LED attached directly to your voltage source will cause the LED to turn on if a bright light is shined on the photo cell, if you want the light to turn on when it's dark that will require a transistor.
 
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