The Peasant enjoys spending time at local concerts and music festivals, and one year decided to build a flashlight to take along using four of the new white super-bright LEDs. There was a bag of RGB flashing LEDs nearby, so six of these were added for a special effect. This type of LED cycles though a short pattern of slow and fast flashing of different color combinations, using an internal IC chip, and are very bright and eye-catching.
Most small AA battery type flashlights use two cells, but that does not supply quite enough voltage for these LEDs, so parts from two plastic flashlights were joined together to allow room for three AA cells. The LEDs were mounted in the head of the flashlight with epoxy, with the four white ones in the center pointing forward surrounded by the six flashing LEDs pointing outwards. A small slide switch was added to select either white light or flashing colors.
Below are some pictures of the white light and the flashing lights. Unfortunately they really don't show the flashing effect very well, as they are not animated and the high output of the LEDs washes out the colors.
The flashing LED flashlight was a huge hit at that year's festivals. Some friends wanted some for themselves, so I decided to make a few more. The next one that I built was similar to the first one, but only three self-flashing LEDs were used instead of six. However, three RGB non-flashing LEDs were also installed, and three small independant flasher circuits were built, one for each color. As well, four smaller single color LEDs were added, two on each side of a multivibrator circuit. Four white LEDs for regular flashlight use were installed as before.
A larger head was needed for the extra circuitry, and a clear plastic cap from a spray bottle was used for this. A three position slide switch was also installed. Again, the pictures don't really do the flashing light effect justice.
Next, a smaller flashlight was built that was designed to be strapped to a wrist with velcro. It has two white LEDs, two RGB flashing LEDs, two regular RGB LEDs, six smaller single color LEDs, and four discrete flasher circuits. Two push button switches in the back and a battery holder on the bottom complete this flashlight.
Another nice light show!
Buoyed with the success so far, a more ambitious project was undertaken. This flashlight has three different modes of operation, regular flashlight, flashing LEDs, and sound-operated light. More voltage was needed this time, so two double AA battery holders were attached back-to-back for a total of four AA batteries. Three small circuit boards were constructed, one for the switches and controls, one for circuitry, and one for the LEDs themselves. These were the stacked on top of each other and wired together attached to the battery holders. Plastic tape to protect the electronics and a small plastic base was also installed.
The display uses four white LEDs for regular flashlight use, four RGB flashing LEDs and eight single color LEDs powered by two flashing circuits for the flashing mode, and three regular RGB LEDs and nine single color LEDs for the sound-operated display in the center. The first picture below shows the four white LEDs, the second and third are the flashing LEDs, and the last is the flashing LEDs with all of the sound-operated LEDs on as well.
The sound-operated mode uses a five-step discrete bar graph circuit to drive a multi-LED display. An electret condensor microphone and preamp supplies the audio signal to the display circuit. The pictures below show the level of light getting higher with the audio signal, but what they don't show is how the color of the light changes from dull purple to blue, green, red, orange, and finally yellow and white as the sound gets louder. It is a very nice effect, almost looking like a flame dancing to the music!
Below is the schematic for this flashlight, any general purpose small signal transistors should work here, I just used the smallest I could find salvaged from old electronics. For other LED flasher diagrams just do an internet search for "led flasher circuit".
Next to be built was a more compact sound-activated light. A small 4 AAA cell enclosed battery holder was obtained from Radio Shack and a small LED ring display circuit attached to the front with epoxy. The microphone is in the centre of the display and the white trimpot on the right is for sensitivity adjustment. The whole package is only about the size of a pager, it fits easily in a small pocket.
Here you can see the display changing with the music.
Well, it looks like I shouldn't have too much trouble locating my friends at the next concert, hopefully our light show won't compete with the one on stage too badly!
For information on other LED lights, check out High Intensity LED Lamps for Portable Lighting.
