His pocket-sized “HexBright” flashlight provides super-high light intensity, up to five times that of conventional LED flashlights. It will be offered in two models — the Prime, with maximum output intensity of 350 lumens; and the Flex, a reprogrammable model controlled by an embedded microprocessor and offering 500 lumens of light output.
"I made myself a light the way I wanted it,” Carlberg recalls. “I picked the best available LED (a CREE XM-L), a good rechargeable battery, built the electronics and programmed it with the only modes I wanted: high, low, and blinky. From necessity (also known as cheapness) I machined the body out of 1-inch aluminum hex bar stock and came up with a unique elegant look with a surprisingly comfortable grip. Based on the aluminum hex-bar body, I named my light the HexBright Prime, and I was pretty happy with it.”
But Carlberg soon came up with more ideas for enhancing the HexBright design. So he and his friend Terry Cooke set about developing a higher-end version, dubbed the “HexBright Flex.”
The Flex adds a mini-usb plug, enabling the built-in microprocessor’s firmware to be re-flashed from a PC. Additionally, it incorporates circuitry for charging its lithium-ion battery from DC power supplied over the usb cable.
But by the time the Flex design was completed, they realized they were “tapped out of cash to actually make one.” The solution to this was to pre-sell HexBright flashlights on the project’s Kickstarter page, where supporters are offered “reproductions of the original and first-made HexBright Prime for just $35, or you can pre-order the more powerful and versatile HexBright Flex for $60.” For reference, “a good quality $30 brand-name flashlight puts out 100 lumens of light,” Carlberg adds.
As seen in the diagram, the heart of the HexBright Flex’s embedded electronics is an Atmel ATmega88 microcontroller. This highly integrated chip contains a low-power, 8-bit, 20MHz, RISC CPU; 8KB flash, 1KB SRAM, and 512B EEPROM memory; an 8-channel 10-bit A/D converter; three timers supporting pulse-width modulation (used for LED control); and one serial port, which is transformed by a chip on the Flex’s circuit board to a usb port.
The Flex’s microcontroller (uC) varies the light intensity via PWM (pulse-width modulation). You can change the light intensity and switch between modes with the only limit being creativity and the program memory of the uC. The uC has a battery voltage monitor input, so you can change up your program depending on how much charge is left. The uC recognizes when the Flex is charging and informs the user via some light flashing signal. It also has an onboard temperature monitor, so it can keep the system from overheating and optimize the efficiency of the LED. Additionally, it has a current monitoring input, so you could potentially keep constant brightness even though the battery might be draining.
When we asked Carlberg why would anybody want to program their light he responded. "Well, LEDs are just a part of an integrated circuit nowadays, and the high performance SMDs (surface mounted diodes) are run by a microcontroller. Might as well put a really good controller in place and give people the option to program their light they way they want it. Me, I like on/off at 200 lumens but when I need the extra power I can hold the button down with my thumb and half a second later the light jumps from 200 to a blazing 500 lumens. Someone else might like a ton of blinky modes. Someone else might like a sinusoidal light wave function. We designed the FLEX to be as flexible as possible for every person. I figure everyone would want to modify their own light given the option."
We would have to agree with Christian. He released this idea on Kickstarter about thirty days ago, has almost 2000 backers, and has raised enough money to place him in the top 15 most funded projects.
It didn't take us long, here at Nuts & Volts, to decide that this project was not only really cool, but deserved our support. We became backers early on through the Kickstarter page, and encourage anyone who would like to have one to do the same.
Go to www.hexbright.com to get more information.
Great job Christian!