Electronics question

Electronics question

I was sitting in my physics class today daydreaming when I whipped out my digital voltmeter, infinty ultra, and e1l. I connected the terminals of the voltmeter to the infinity ulta's cntacts and beamed the e1l at the LED. I measured .5 volts! My question is: Is this an example of the photoelectric effect ( Photon on metal causes electron jumps) or is it just the LED heating up and creating heat?

-tom

Re: Electronics question

I can't help you with your question, but that would have been a great question for your Physics teacher.

Re: Electronics question

Wouldn't that be the basically same photoelectric effect that an infrared (LED) receiver has when energized by the IR (LED) output on a remote control?

Re: Electronics question

I dont know. My Physics teacher (this is his first year) thought it was the photoelectric effect also.

-tom

Re: Electronics question

Most LEDs can be used "backwards" as photovoltaic cells. As an example, I have a little power line monitor thingy from Fluke. It's just a little sealed plastic box with an AC plug on the back and an LED on the front. It's meant to plug into a wall socket to monitore the power line for disturbances. When it catches something, it blinks the LED.

Whenever people see it, their first question is "how do you get the stored data out of it?" The answer is that the LED is used in "ping-pong" mode in conjunction with an optical probe. When you plug in the probe, it interrogates the device via the LED and starts up a file transfer via this optical path. Pretty nifty use of an LED. /ubbthreads/images/graemlins/cool.gif