I have two issues that, while they are not really Empeg-specific, I thought would sit better here than in OT.

#1 5V power supply

I need to build a 5V DC power supply to run a Netgear WAP on my boat. It's OEM AC power adapter is rated at 1.0 amp output. The new power supply will run off the 12-volt batter bank on the boat.

I found a schematic for a very simply step-down power supply that even an electronics idiot like me might be able to follow. It says that the 7805 can be increased to 1A output by adding a heatsink, but it doesn't say if any other changes need to be made (other than a heatsink). Also, I have in my possession a 7805 CK that does the same thing and is rated up to 3A.

My question, if I built this with the 3A-capable 7805CK, would I need to adjust the values of the other components (capacitors)?

Also, one of the statements on that page "Change the transformer from where you take the power to the circuit to a model which can give as much current as you need from output" just didn't make sense.

#2 Taking speed sensor (VSS) input on the serial port

I am installing another axle-mounted, drop-to-ground pulse, speed sensor on my car. I estimate that with my tire size it will generate between 750-800 pulses per mile, so say 750 pulses per minute at 60MPH and 1500 PPM at 120MPH.

At the high limit of 120 MPH, that would nmake around 25 pulses per second. My intent is generally to follow the interface diagram here and the author of that software mentions the shortcoming of RS232/serial handling under Windows. my question is whether this rate of serial port pulses-per-second would be an issue if I were going to try to implement it on a Linux laptop or the Empeg. Is there any other serial library of something that I should be looking at? I think this may have come up in a previous speed sensor thread, but i couldn't find it...

(Man, I am in *serious* work avoidance mode this Friday morning!)
Thanks,