I was hoping to get some feedback on my PCB design - this is my first attempt at having a PCB manufactured. I re-routed this board maybe 15 times and I hope I finally got it right! Also want to make sure i am not doing anything blatantly wrong. I did have to redo and shrink the layout a few times to get it to 10cm x 10cm for the PCB fab.
What it is - This will be my controller for my aquarium hood.
* Atmega168 with arduino bootloader
* MCP23008 GPIO controls 7 TIP120 transistors: 3 to turn on and off relays, the remaining 4 control 12VDC fans. The fan headers are on the right, each of the 4 circuits drives 900 mA.
* DS1307 real time clock, also on the i2c bus
* TLV2374 rail to rail op-amp attached to PWM pins from Arduino. These are for 3 0-10 VDC outputs which control the dimming of my T5 Ballasts.
* 2 voltage divider circuits on the analog inputs with thermistors, to measure the temperature of the hood and the water.
* the remaining pins of the arduino route to a header for buttons, encoders, LCD, etc.
* input is regulated 12VDC, on the lower left of the board is the voltage regulator circuit.
i only had small breadboards, so my prototype is a bit of a mess, but it works.
Here is the prototype:
Here is a picture of the layout and links to the Eagle Schematic & Board layouthttp://dl.dropbox.com/u/57349766/Fish/LC.4.schhttp://dl.dropbox.com/u/57349766/Fish/LC.4.brd
I still need to complete putting labels on all the parts. Any feedback, comments, etc is appreciated.