Build a Color Changing, Battery Operated LED Night Light

by Jenn Nelson

31K2611

Intro: Build a Color Changing, Battery Operated LED Night Light

A small but mighty battery operated night light. Select from different solid color modes, or disco flashy mode! Would also make an excellent bike light. Built from 7 color LEDs and a dot-it.

I found these LEDs while buying components for another project. I had an dead dot-it lying around, and was struck by inspiration.

I made a video, since photos don't really do it justice. Check it out.

STEP 1: Materials

I started with three 7 color flashing LEDs, three 51 ohm resistors, a small round circuit board, and a SPST momentary push button switch from Radio Shack. You'll also need a "Dot-it" LED battery powered light. From your toolbox, you'll need some wire for jumpers, wire cutters, needlenose pliers, technical screwdrivers, solder, and a soldering iron. I found a glue gun, a set of "helping hands" (a stand with a magnifying glass and alligator clips,) and a desoldering iron helpful, but they aren't crucial.

STEP 2: Loosen the Glue

Start by twisting the dot-it to loosen the 3 glue dots on the side that are holding the cover on.

STEP 3: Unscrew the Battery Cover

Use a phillips 0 to unscrew the three small screws holding the battery cover on. Remove batteries.

STEP 4: Pry Off Cover

Using a slotted screwdriver, carefully pry off the cover. It's only held on with three dots of glue.

STEP 5: Remove Cover

Once the cover is loosened, carefully pop it out. Remove the lens and reflector, and set aside. You'll need these parts again soon.

STEP 6: Remove Old Guts

Use your soldering iron to melt the solder connections and remove the old circuit board. It's printed, and won't work for our 7 color LEDs. I removed the nice, bright white LEDs so I could use them in another project.

STEP 7: Make New Circuit Board Fit

I had to file a bit off the edges to make it fight right.

STEP 8: Tack LEDs in Place With Hot Glue

I used hot glue to temporarily hold my new LEDs in place in the reflector so I could be sure they would line up with the holes later. Only use a little so you can pop it off later.

STEP 9: Fit Circuit Board Onto LEDs

Push the circuit board onto the legs of the LEDs. Since they're tacked in place in the reflector, they won't move around. Make sure that the reflector fits in the case right, and that the circuit board lies where it is supposed to.

From this point on, test everything frequently or you may be very sad once you get it all back together.

STEP 10: Attach Resistors and Switch

Solder a resistor in place on the non-foiled side of the circuit board (with the LED's.) One leg of each resistor should be attached to the CENTER leg of each of the LEDs. The other leg of each resistor should be soldered to all the other resistors. The hot (positive) from the batteries will be soldered here. Add your switch now too. DO NOT SOLDER THE SWITCH TO THE POSITIVE. I know this seems counter-intuitive, but the switch is for the "control leg" of the LEDs. If you find a micro-sized switch, no modification is necessary. If, like me, you can only find a submini switch, you will need to drill a hole in the reflector and the cover. It's messier, but works just fine. The original switch is NOT a momentary switch and can't be used.

STEP 11: Wire Jumpers and Leads

Almost there! Now that your "hot" has been soldered to the resistors, it's time to hook up the neutral and the control legs. The leg with a 90 degree bend near the top is the neutral. Use jumpers to wire these all together. Add a lead that will go to the neutral end of the battery holder.

The leg with the slanted top is the control leg. Use jumpers to attach all of them to one leg of your switch. Next, solder a jumper from the other leg of the switch to your neutral lead and neutral jumpers.

When the switch is pushed, it will interrupt the neutral going to the control leg, which will cause the LED to jump to the next stop in its cycle. Do not interrupt the positive; the switch on the control leg will turn the light on and off.

Solder the other ends of the hot and neutral leads to the battery holder.

STEP 12: Reassemble and Enjoy!

push the circuit board and reflector back in place. Snap on the lens. I bent the cover in slightly around the edge and it "grabbed" the battery holder fine, but you could glue it back in place, I guess. Put in your batteries, and screw the battery cover back on.

Once you put in the batteries, the LEDs will go through a test cycle that can only be described as "surprising." That's why you don't want to interrupt the hot. Once they appear to turn off, you're ready to go. Each time you push the button, it should move through each step of the cycle as follows:

red
off
green
off
blue
off
amber
off
aqua
off
magenta
off
white(ish)
off
disco color change
off

Push button repeatedly and enjoy!

10 Comments

50057995 4 years ago

How much electicity does it use

CP LED 11 years ago

plz tell me were to get dese leds i live in india online radioshak doesnt give fecility in my city

Jenn Nelson 10 years ago

Did you try to order from radioshack.com?

Luka Sotra 10 years ago

So uh, if i wanted to replace the LED's with lets say UV ones, can i just disconnect the standard white ones and just solder the new ones on or is there some other complicated process involved? :)
I'm working on a nuka cola quantum "project". And i think it would look absolutely amazing if i could replace those lights with the above said UV's.

Jenn Nelson 10 years ago

Yeah, I actually have made a bunch of these as blacklights. The biggest issue is the resistor; so double check and make sure you don't have to replace it with one appropriate to the UV LED's you have. You don't have to replace anything else other than the LED's. Stick some velcro on the back for surface mount.

hewstigator 12 years ago

Thanks so much for this Jenn!!! just completed the project.

Found little wire snips worked like a charm to cut the PCB down to size... (for those too impatient to sand)

the hardest parts (for my simpleton brain) were (a) figuring out the right place to jam my flathead screwdriver to pop the cover off (i spent a little time mauling the silver casing at first before i realized what i was doing... ended up noticing there is even a little notch that helps you pry off the cover correctly haha, doh!) and (b) properly insulating everything so that when i crammed everything back together there would be no shorts...

but all in all, those were only minor hurdles, and i am really digging this thing - thanks again for this great tutorial!!!!!!!

Jenn Nelson 13 years ago

I'm working on a diagram for you, but I'm in the middle of another project (surprise, surprise) so I'll get on it eventually. The 3-leg LED's are RGB with an IC inside the LED itself; that's why there's a 3rd leg, and why they can change color.

asporkable 13 years ago

I got a little lost on the wiring step. Any chance for a wiring diagram?