Basics: Simple LED Pumpkins

Awesome little LED Jack-o'-lanterns are quick and easy to build yourself, in the tradition of LED throwies. Special bonuses: (1) Now with candle-flame flickering LEDs and (2) way brighter than those little LED tea lights!

The basic ingredients are a simple LED-- preferably blue or white (we'll get to why in a moment) --and a CR2032 coin cell. We're using diffused-lens 10 mm warm white "candle flicker" LEDs, which contain a built-in flickering circuit that imitates the random fluctuations of a candle flame. You'll also need some tape, for example masking tape, to hold it all together.

If you slip the leads of the LED around the coin cell (long lead of the LED towards the + side of the battery), the LED lights up, and you can then use tape to hold the leads of the LED in place. Hopefully you can also use the tape to help keep the electrical parts separate from residual moisture inside your pumpkin.

Now, about that color selection. LEDs towards the "blue" end of the spectrum (blue, white, warm white, deep green, and ultraviolet) will run like this for up to two weeks on a single battery, if you keep it dry and not too cold. (And twice that, if you turn it off during the daytime.) But what if you have, say, a yellow LED?

LEDs at the "red" end of the spectrum (those with red, yellow, orange, or yellow-green colors) --have a lower "forward voltage" and therefore will draw much more current and eat through a battery much faster.

A solution is to add a series resistor (say 50 - 200 ohms), by twisting the resistor lead with the lead of one of the LEDs, so that the LED runs at much lower current, similar to the amount that the blue and white LEDs use. More about that technique can be found here.

One nice side benefit of using a resistor: That third lead makes a great pushpin to hold your LED to the roof of your pumpkin.

Next, the carving part. We have here two small decorative gourds-- on the left and right --and a white mini-pumpkin in the center.

As we have noted in the past, mini-pumpkins tend to lose their shape only a few days after carving. Small decorative gourds like these are somewhat harder to carve, but last much longer.

At this point, simply insert the lit-up LEDs. Ideally, anchor them in the lids or otherwise position them so to that the LED isn't directly visible.

The LEDs that we're using are 10 mm diffused-lens types, which have a huge viewing angle, and light up the entire inside of the pumpkin or gourd. Indirect lighting gives a much better candle-like effect, and looks particularly cool in a pumpkin that's too small to support a real candle flame.

And here is super quick video, showing the process, with the flickery results:

(Video is embedded above. Click here to see it on YouTube if you can't view it here.)

Ready for deployment on porch or windowsill!