PicoLogoFun

Week 1, and I immediately got caught up with having way too much fun with the PicoBlock software - so much that I forgot to finish the lab exercises!

There were a few stumbles along the way in connecting the LogoChip to my MacBook. The driver for the SparkFun USB-Serial Boards was not getting installed properly on Mac, and I had to move to a lab computer. But once that was resolved, it was smooth-sailing. I spent a lot of time exploring the Getting Started with LogoChip, and described in the next few posts are some of the little projects I found most interesting!

Light Emitting Diodes (LED)

Properties of LED:

• Current flows through it in one direction only.
• One electron releases one photon.
• It has potential drop of 2.5V across it.
• Current more than 20mA usually burns out an LED.

Varying the value of the resistor across the LED changed the amount of current flowing through the circuit, which in turn controlled the brightness of the LED. However, cutting R in half does not necessarily mean twice as bright LED. 

For example,

Assume Vp = 6 V

VLED = 2.5 V

VR = 6-2.5 = 3.5 V

I = 3.5V/1kohm = 3.5 mA

If we half the R, so that R = 0.5 kohm

I = 3.5V/0.5kohm = 7 mA ????

Voltage Divider

Everything we are going to see in the Electronics section for the rest of the time can possibly be explained in terms of voltage divider.