Comments on: Improving the Ping Pong Ball LED Diffuser

By: Dave Eaton

Dave Eaton — Fri, 28 Mar 2008 03:17:23 +0000

Acetone applied carefully to the cut edge of the ping-pong ball will act as a good glue. It dissolves the ball just a little. You have to be sparing with it- I use a cotton swab.

I have used ping-pong balls as molecular models. I think illuminating them would be cool.

I’ve been playing with some UV LEDs. If you could write a message on the inside of the ball with a colorless, but fluorescent ink or paint, then turn on the UV LED to display the message, that might be pretty clear and distinct. I will look to see what will work.

By: dfowler

dfowler — Sun, 09 Mar 2008 07:59:12 +0000

Mr Meval,

I tried that first. Just placing the LED against the side of the ball did light up the ball, but it was very dim.

By: Mr. Meval

Mr. Meval — Sun, 09 Mar 2008 07:42:30 +0000

I would be curious to try that but not open the ball. Just shine the LEDs at one side and look at the other. If that worked you can cut a slit in the ball and insert what ever text you want. It would be interesting to insert an LCD that would display text.

Hrm. I have a cheap two dollar LCD clock just begging for a some treatments…. It’s the sort that has no reflective back so shining a light through it works and I can shine the light from the front…

By: Charles

Charles — Sun, 02 Mar 2008 14:38:16 +0000

You could use a red and green or a bicolor LED, and label using red and green markers, then when lit with green, the red marker would show, and when lit with red, the green marker would show, so you would have two separate messages from a single diffuser.

By: m

Fri, 29 Feb 2008 20:56:02 +0000

Hi,

Here is a variation for the ping pong ball I’ve made recently : by using a small NPN transistor, a CR2032 battery and a soda bottle cap, your can make a led “floatie” in 10 minutes or so.
This “floatie” will automatically light up when floting in the water. I’ve thrown quick and dirty schematic there http://misomosi.free.fr/static/ (many many apologies for the quality…).

The general idea is to use a soda cap, put a CR2032 bat in it, and make 2 holes in the cap to slide 2 electrodes : one from the transistor base, the other from the bat+. When in water, enough current will flow to turn on the transistor. LED+resistor is soldered from between the transistor emitter and the bat-
(I sand the LEDs w/ 100 grit paper).

Make a hole in the ping pong ball, glue the soda cap (containing the electronic) to the ball, and you have a nice, automatic LED floatie.

By: dfowler

dfowler — Fri, 29 Feb 2008 02:05:15 +0000

Murli,

I used a small file but I beleve an exact knife would work as you sugest. It was very easy for me to cut the ends off.

By: murli

murli — Thu, 28 Feb 2008 17:36:47 +0000

i suggest u use a xacto knife or some small sharp blade to scrape the smooth surface of the led it provides good diffusion of the led light.i tried using the blade and it worked well for my bright white led!

By: tony

tony — Tue, 26 Feb 2008 20:09:55 +0000

Try transparent silicon, the one used for sealing. Make like a finger of dry silicon (with plastic tubing to get the form for example) then drill a hole or simply a deep cut and then place the led inside…thats how I do it.

By: Al Williams

Al Williams — Mon, 25 Feb 2008 17:05:09 +0000

Very neat. I would think a Dremel cut off wheel would slice the top of the LED even easier than the coping saw.