sample 1

Introduction to Physical Computing
Week 1, Lab: Electronics

Here is the ITP intro physcomp link for the lab.

Step 1.

The lab writeup doesn't say much about the LM7805 voltage regulator.
I recommend checking out the datasheet.

I think National's site is pretty easy to understand, and they'll send
you free samples if you ask. You'll want to put 12V (your power source)
on the "IN" side, and the "OUT" will output 5V.

Step 2.

220 Ohms, think Red. And red.

Step 3.

The voltage is equally dispersed between the two LED's (~2.5V).
5/3 volts (1.6V) isn't enough to power 3 LED's, so if you inserted a third none
of them would light. And the world would be dark.

Step 4.

When I measured the amperage, I read 60 mA. I assume that this is
because it was the amperage across all three LED's in the parallel
circuit, which works out to 20 mA per LED (much more reasonable). I
returned to a single LED (w/resistor) and read the amperage which was
~20 mA.

Step 5.

I love things that turn.

Up

-- Sun, 09 Sep 2007 21:26 -0400