Get your boy the Electronics Learning Lab, and yourself one as well.

That way you won't have to fight over it.

You probably won't find them again as cheap as they are right now. They really are a great bargain.

 

I will.

One question. I never noticed this, but there is a slight glow to the LED when the S1 is open (when garage door is closed). Any ideas where the current is coming from?

 

The LED could be getting a very small amount of current through the 2N2222 due to leakage. That is why I suggested adding the 10k pull-down resistor between the base and emitter. There will still be a slight amount of leakage. LEDs will still glow dimly with even a very small amount of current.

It could also be leakage backwards through the 7805 regulator.

Here's a slight mod to the next version:

Basically the same thing, except Q1 is now a PNP transistor instead of an NPN transistor. This way, the +12v supply is switched instead of the circuit ground.

D4 was added to prevent the LED from getting powered by leakage from C3 through the 7805 regulator.

R10 is optional; as we've already discussed, it provides for adjusting the output voltage of the 7805.

R5 is still optional.

 

That's a neat design. I am going to get the parts and another breadboard or 2 and work on it this winter. I know now that when I breadboard it I will hook the breadboard into it's "real" location to make certain it works well. I may also use a couple of trimpots on a couple of those resistors to give me some flexibility.

It will be a fun project. I hope to really work on the final layout to shrink it as small as possible.

Thanks
Jeff