Go Down

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


Okay, new board ordered, new parts ordered.  Now I wait for a month...

If I get time to cut the hole before my new board gets here, my old one is going in in the mean time.  I'll just plug the new board in when it gets here.  I'm already glad I made it modular. :)

kevin duino


i make this sugestion to every1 doing a car project. Get another car battery for your project. that way, you dont have to replace your car's so often

That doesn't make any sense.

what do u mean?


What he means is that it doesn't make sense to add another car battery just for a project.

When you say wouldn't have to replace it as often, I assume you mean one of two things:

A: The car's battery would be drained by the electronics.
B: The battery will be worn out more quickly by the extra load.

The battery in a car gets recharged constantly as the car is being ran.  So it wouldn't be drained by the project.  Car batteries aren't replaced because they run low like some AA's in a gameboy.  They are replaced because, like any rechargeable, they stop holding a charge after a length of time, or charge cycles.  Really, the only time a battery is being discharged in when your car is off, or being cranked.  After that, the alternator supplies enough power for everything.  You can crank a car, then remove the battery entirely, and it will continue to run! (assuming your alternator is healthy)

As for B, the amount of current that these projects pull is relatively low.  Simply turning on your radio easily pulls more than my whole project.  Turning on your headlights, even more so.

So adding another battery to power these projects wouldn't make sense.  The car's battery keeps itself charged, is already there, and isn't adversely affected by it.  (would barely even notice)

Also, from your post here:
You shouldn't really control voltage with just a resistor.  The reason is that your voltage with fluctuate depending on how much current your load draws at the moment.  Take a look at Ohm's Law, it will explain it fairly well.  This is why voltage regulators (such as the 7805) are used.  They hold output voltage steady independent of load.


My redesigned board should be in next week, but since it's a direct swap for the other board, I see no reason to wait for it.

So I finally cut that scary, scary hole.

I was somewhat torn between putting the keypad underneath the door handle, and next to it. Most people I asked seemed to like it underneath, while I kind of preferred next to. Well, inside the door there is this "stuff". It kind of looks like metal painted on the inside of the door skin. For strength? Sound dampening? Something else? I don't know, but it made the door skin much thicker there (underneath the handle), so my decision was pretty much made for me.

Close up of metal "stuff".

Here are my practice holes. This allowed me to not only get used to cutting with my Dremel, but also work out the exact shape and size I needed to cut. I used the thin metal cutting disc for the Dremel. It worked well.

Here's the door with my template on it and taped up a bit.

Hole cut.

Looks a bit rough. (those marks below the hole are just dust)

The hole retaped, rough edges filed, and paint cracks sanded away.

Retaped and primer paint applied (to inhibit rust)

Dried and untaped.

Last shot of keypad and clip.


Back of keypad up inside the door.

Keypad on door. (not as crooked as this picture makes it look)

And a nice wide shot of the door.

Hopefully my next update will be when I have the wiring finished!

Go Up