<<< Back to Eric's Robots

LED Thermometer

I built a thermometer out of some very bright green LEDs that someone donated at the AHRC meeting and an Atmel AT-MEGA8. The AT-MEGA8 is WAY OVERKILL for this project. It runs a 4 MHZ and has 8K of flash. But I wanted to test out the Linux Atmel programming tool chain. I am hoping to build a sign for Annie's lemonade stand in a similar fashion.

Major Components

Qty Description Source
1 LM34 Temperature Sensor (degrees farenheit) glitchbuster.com
42 Really bright LEDs kind donation at AHRC meeting
9 2N3904 NPN Transistors Jameco
1 Atmel AT-MEGA 8 Digikey
1 4" x 9" sheet of Lexan All Electronics

Source Code, Hex File

Now, I'll bet you are going to ask me for the schematic next... (there is none.)

I had great difficulty getting the 'top' transistor to work for controlling which segment was active. I think there is something wrong there. When I described how I got it to work (adding a couple of diodes), some folks said that I shouldn't have had to do that.


The thermometer is with my step father right now. He's building a case for it.

Home | Contact Us       Copyright 2008 Eric Z. Ayers