Tap Light LED Auto-Off Hack

After reading this nice tutorial I thought I'd post an instructable to show everyone how I accomplished making myself a few tap lights with a delayed turn-off. My wife always forgets to turn lights off and I knew I had to install these in our closets with a auto-off feature! For my setup I used the following parts, you can play with the capacitor and resistor to adjust the delay in turning off the LEDs. This setup will keep the LEDs on for about 3 minutes before they get too dim to be usable.

First off, let me give credit for the inspiration for this project. I had seen this article posted a few weeks back while reading through my RSS feeds by Dane Kouttron. Fantastic article and he even explains the principals behind this very simple circuit!  http://transistor-man.com/lampfade.html

Here is what you are going to need:

1. (1) 100uF Electrolytic Capacitor
2. (2) 1M Ohm 1/4W Resistors
3. (3) Super bright white LEDs
4. (2) 68 Ohm 1/4W resistors (depending on your LEDs) Do the math for the resistance needed!
5. (1) 2N7000 N-CH Mosfet
6. (1) 12mm square momentary switch. Normally off.
7. (1) Tap light of your picking! I've listed the one I used.
8. A small piece (~4 inches) of wire.
9. Solder, soldering gun pliers, wire cutters, third-hand and about 20 minutes.

I strongly reccomend you check the prices at www.taydaelectronics.com for parts! I have ordered from these guys many times and I get my order quickly and accurately every time. They are located in THAILAND so shipping to US is about 2 weeks.

Step 1 Which Type of Light?

I don't think it really matters which type of generic tap light you get. Just look for the cheapest you can find that isn't already using an LED (they are usually more expensive). I found mine on Amazon for $1.77 US. I went ahead and got (10) of them for the various closets and areas I wanted a handy light.

Comments

[Nodent]

This is exactly the circuit I was looking for. I play paintball and make mask fans. Problem is I make them to quiet and forget to shut them off. What specs would I need for about 15 minute run time of a 5 volt fan .4watts running off of 4 AAAs or 3AAAs? Looking for a very small circuit.

[Emperor Dane]

THIS IS SO AWESOME.  Thank you INTERNET for again, making my day

GREAT INSTRUCTABLE, so detailed. great pictures Thanks for the reference link. Glad my site was helpful.


-Dane
transistor-man.com