On 06/04/2016 10:01 AM, HerHusband wrote:
The LED itself regulates voltage. That's what a diode does.

http://www.merriam-webster.com/dictionary/diode
an electronic device that allows an electric current to flow in
one direction only

It has been many years since my electronics days, but I believe a diode
does have a fixed voltage drop. I think it's around .7 volts if I remember
correctly. So it does regulate the voltage in some respects.

The (forward) voltage drop depends on the semiconductor material. .7V
for silicon diodes, around 2V for LEDs.

Reverse voltage drop can vary greatly according to design. I've see
about 3V (for a LED) to 1KV (1N4007 IIRC).

With either polarity, voltage exceeding that will cause current to flow.
This is called "breakdown" and is not harmful unless the diode's maximum
current is exceeded. A LED is normally operated in forward breakdown
(necessary for it to light).

A diode is a voltage regulator. If you connect a LED (and nothing else)
to a car battery, the LED will try to bring the battery down to 2V, and
try to handle nearly infinite current. I did this once and didn't even
see any light before there was a POP and half the LED disappeared. You
need a resistor that drops the excess voltage (10V here) without
exceeding the LED current (typically 30mA).

Anthony Watson
www.watsondiy.com
www.mountainsoftware.com



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