I am trying to maximize the amount of light that a red laser produces when it hits a cadmium photo cell.
I went from a photocell with a small area to one with about double the area.
I salvaged this from a laser printer and was wondering if that clear thing is a fresnel lens?
Am also trying to figure what that clear led is.?
There is a drawing on the circuit board that looks like this.
LD1 A |-->|C
Thanks.
No, it's just an ordinary lens made from moulded plastic.
Cheers
Phil Hobbs
certainly looks like a lens, if it has a ring structure it could be fresnel, but such a small lens wouldn't need to use material saving strategies like fresnel.
Some sort of diode, probably an LED (possibly infrared), might be a photodiode
What is written next to other LEDs?
use multimeter diode test to check the voltage threshold.
thanks Jasen.
1.43 v is the approx forward voltage drop.Andy
Did it light up? Try looking at it with your cellphone camera, it can see light that your eyes can't. Mikek
It did not put out any visible light using just the diode test.
Cell phone did not pick up anything.
Andy
Cell phone video shows a purple blinking light when I use my tv remote.(uses 2 AA batteries.)
The circuit that contains the "IR" led, has some 178 resistors and two 34 ohm resistors in series that go to the IR led.
Is it possible that the 1.74 volts going to it isn't enough voltage to light it?
Andy
It's a LED, possibly infrared, photodiodes are usually lower voltage, especially in consumer equipment.
it may still be possible to use it as a photodiode.
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