Do-It-Yourself LED Flashlight

2005 - Volume #29, Issue #3, Page #32

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You can make your own low-cost LED flashlight by using pvc pipe and electric components commonly available at stores like Radio Shack, says David Strenski, Ypsilanti, Mich., who recently called FARM SHOW to tell us about his light.
  "I was completely hooked after the first one I made was left on overnight and the LEDs were still as bright as new the next morning," says Strenski.
  He has since gone on to make several more flashlights, using 1-in. dia. pvc pipe. Power is provided by three C batteries. Since LED lights consume so little power, he decided to solder the wires directly to the batteries. "The design requires no springs or metal pieces and provides a more reliable connection," he says. A toggle switch is used to turn the power on or off.
  According to Strenski, LED flashlights have become more popular in recent years because LED technology has gotten better. There's no glass or filament, so if you drop the flashlight there's nothing to break. And best of all, LED flashlights are typically rated for tens of thousands of hours because they use so little power.
  "The cheapest commercial LED flashlight I could find was a two-bulb model that sold for $30. One 19-bulb model sold for $150. That's when I decided to build my own. I've built several different models for between $15 and $20.
  "Advertisements for retail LED flashlights claim about 50 hours of full brightness and another 100 hours of usable light, all with a flashlight that has only two AA batteries. I'm using three C batteries, so my flashlight should last much longer. I'm always improving the design and looking for cheaper sources for different color LEDs and cheaper switches," he says.
  He discovered that a C battery fits perfectly inside a schedule 40 pvc water pipe, so he used it for the main portion of the body. A pvc cap fits over the bottom end.
  Each battery has a voltage of 1.5 volts. For LEDs needing 3.0 or less volts, he trims the pipe to hold two batteries. For LEDs that need more than 3 volts, he uses three batteries providing a total of 4.5-volts.
  The torch end of the light is made from a pvc coupler. A lens cut out of plexiglass is shoved into one end of the coupler, up against the stops.
  The torch end of the light is made from a pvc coupler. "You can glue a clear plexiglass cover on the end, but I find you don't need it," says Strenski. He solders the LEDs onto a small circuit board that is trimmed to fit inside the coupler and rest against the stops. A small resistor needs to be soldered onto the positive lead of each LED to step the voltage down from the battery voltage to the voltage needed for the LED.
  Strenski continues to work on new variations of the flashlight. "To make my third and fourth flashlights I bought white ($1.24) and red (56 cents) LEDs from SuperBright LED.com, and was able to fit nine of them on the circuit board. I've also found that I can get really cheap 99 cent, plastic flashlights that I can rework into LED ones, but the circuit gets tricky since it only holds two batteries and for the white LEDs I need to step the voltage up with a DC/DC converter. I'm still working on that design."
  Strenski sells a 3-page instruction sheet for $5. He's working on a short instruction book that he'll make available in the future.
  Contact: FARM SHOW Followup, David G. Strenski, 323 Oak Street, Ypsilanti, Mich. 48198 (ph 734 480-1587; email: dave @strenski.com).

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Do-It-Yourself LED Flashlight FARM HOME Miscellaneous 29-3-32 You can make your own low-cost LED flashlight by using pvc pipe and electric components commonly available at stores like Radio Shack, says David Strenski, Ypsilanti, Mich., who recently called FARM SHOW to tell us about his light. "I was completely hooked after the first one I made was left on overnight and the LEDs were still as bright as new the next morning," says Strenski. He has since gone on to make several more flashlights, using 1-in. dia. pvc pipe. Power is provided by three C batteries. Since LED lights consume so little power, he decided to solder the wires directly to the batteries. "The design requires no springs or metal pieces and provides a more reliable connection," he says. A toggle switch is used to turn the power on or off. According to Strenski, LED flashlights have become more popular in recent years because LED technology has gotten better. There's no glass or filament, so if you drop the flashlight there's nothing to break. And best of all, LED flashlights are typically rated for tens of thousands of hours because they use so little power. "The cheapest commercial LED flashlight I could find was a two-bulb model that sold for $30. One 19-bulb model sold for $150. That's when I decided to build my own. I've built several different models for between $15 and $20. "Advertisements for retail LED flashlights claim about 50 hours of full brightness and another 100 hours of usable light, all with a flashlight that has only two AA batteries. I'm using three C batteries, so my flashlight should last much longer. I'm always improving the design and looking for cheaper sources for different color LEDs and cheaper switches," he says. He discovered that a C battery fits perfectly inside a schedule 40 pvc water pipe, so he used it for the main portion of the body. A pvc cap fits over the bottom end. Each battery has a voltage of 1.5 volts. For LEDs needing 3.0 or less volts, he trims the pipe to hold two batteries. For LEDs that need more than 3 volts, he uses three batteries providing a total of 4.5-volts. The torch end of the light is made from a pvc coupler. A lens cut out of plexiglass is shoved into one end of the coupler, up against the stops. The torch end of the light is made from a pvc coupler. "You can glue a clear plexiglass cover on the end, but I find you don't need it," says Strenski. He solders the LEDs onto a small circuit board that is trimmed to fit inside the coupler and rest against the stops. A small resistor needs to be soldered onto the positive lead of each LED to step the voltage down from the battery voltage to the voltage needed for the LED. Strenski continues to work on new variations of the flashlight. "To make my third and fourth flashlights I bought white ($1.24) and red (56 cents) LEDs from SuperBright LED.com, and was able to fit nine of them on the circuit board. I've also found that I can get really cheap 99 cent, plastic flashlights that I can rework into LED ones, but the circuit gets tricky since it only holds two batteries and for the white LEDs I need to step the voltage up with a DC/DC converter. I'm still working on that design." Strenski sells a 3-page instruction sheet for $5. He's working on a short instruction book that he'll make available in the future. Contact: FARM SHOW Followup, David G. Strenski, 323 Oak Street, Ypsilanti, Mich. 48198 (ph 734 480-1587; email: dave @strenski.com).

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