Team 4The Beancounters

Ethan Price, Shicheng Guo, Wesley Tso, Kyle Haver

Solid State Relay ConsiderationsControl signals need minimal amounts of

current: ~30mA. Standard 10mil trace will suffice

SSR1: Mounted on the PCB, will have to pass 1.7A of 20VDC for the fan. This will need to have >50mil traces and molex connectors, plus etxra space between traces

SSR2: Mounted separately from PCB

I2C Considerations100KHz operation; noise, impedance, and

signal length possible concerns (rated to ~1m)

Rule of thumb: <1/10 of wavelength, transmission line effects not a concern

I2C fall time is about 100ns = 5MHzWavelength@5MHz = ~100metersWe're well under 10 meters, not concerned

Power SupplyConversion: 12.6VAC -> ~12VDC -> 5VDCAs with SSR, needs to be relatively isolated7805 will need heatsink, so some keepout

area will be neededHeader pins are rated at 1A each, should be

sufficient for power supply

MicrocontrollerAll voltage pairs have decoupling caps,

need to be placed nearbyWant to attempt to keep uC and headers

away from switching noise of amplifier and transistors

Crystal and associated caps are slammed up against the microcontroller