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Topic: Car Keypad (Read 10 times) previous topic - next topic


My board came in today and it looks good!  I can't wait to get home and try it out.  I ordered two, just in case I royally mess the first one up on assembly. :)  I really would hate to have to wait a whole extra month.  I'll post more pics when I get it all put together.




So here I am, closer to the inevitable car door cutting.

Populating the board:

I got a little better as I worked from right to left. I didn't realize how little solder that SMD parts required.

All assembled:


Testing the board:

Everything works perfectly!

Fitting into the box:

The screw holes line up perfectly. The connectors on each end were a bit taller than I had expected, though. The lid still closes, but it pinches the wires a bit. I'll trim a little useless plastic off the top of the connectors and it should be fine.


May 11, 2009, 07:40 pm Last Edit: May 11, 2009, 07:47 pm by george_graves Reason: 1
VERY COOL - I love to see an arduino put to use in the "real world"

I didn't see much power protection going on there.  What are you doing to keep away nasty voltage spikes and reverse voltage?

(a car's power is notoriously bad)


Thanks George!

I'm not exactly an EE, so I'm real green on most of this.  I knew that car voltages can be nasty, but as per other discussions around these forums, people have been running Arduinos from cars seemingly fine.  The datasheet for the Nano says it should be ok up to 20v.  I hadn't even considered reverse voltages at all, does this tend to happen on a car?  For reverse voltage, one would throw in a diode on the power line?  As for the spikes, a capacitor on the power line?

Honestly the only thing I considered was a drop in voltage on cranking the car.  I doubt much that anyone is going to be using the keypad while cranking, so I didn't think a restart would hurt anything.  I suppose that the dip could lock up the chip instead of just restarting it.  I'll be actually running it in my door soon, so I'll have to see.

If you have any good suggestions for cleaning up the power, or maybe a good place to look, let me know.


May 12, 2009, 05:59 pm Last Edit: May 12, 2009, 05:59 pm by designer2k2 Reason: 1
great project  :)

you should consider some safety for the arduino, there is quite some noise there!

i made this:

just take the input part, that should block the biggest problems

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