wazi Posted March 5, 2015 Share PART ONEBuying the componentsPowerI already have many rechargable AA batteries so to save costs I used them as a start. 4xAA @ 1.5v = 6v total. LEDsI found these LEDs at Rabtron. Decided I wanted 2 per bicycle. They have a "Forward Voltage 3.6V" which means I needed resistors to manage the current coming from the batteries. I used this calculator to work out the resistance needed. The guys at Rabtron confirmed these numbers and suggested I get a 5watt resistor as opposed to the 1.9watt recommended. NOTE: I needed 1 resistor per LED. At the time I wasn't sure if I wanted the lights to be together or split the two on each side of the stem. Components deliveredI chose to use an old water bottle to house the batteries and switches. Convenient and cost effective. I also picked up some small terminal connectors (red ones in the packet) as the MK1 version took too long to solder. I also bought 10m of copper cable for R40 from Builders Warehouse. Circuit diagram Solder the copper wire to the LEDs.Use about 75cm of cable per LED. You can cut it down later if needed. I placed the LEDs on a more than moist tissue to absorb the heat from the soldering. The back of these highpower LEDs are made to conduct heat away from the LED. The soldering job didn't turn out well, I blame the iron. wasn't heating properly. have to get back to some real work now...will post more later. Link to comment Share on other sites More sharing options...
Skylark Posted March 5, 2015 Share What reflector/lens are you going to use with the LEDs?That's quite a significant factor in the quality/usability of the light output. Link to comment Share on other sites More sharing options...
Amberdrake Posted March 5, 2015 Share I am pretty sure you made a mistake there. Not with your calculations or setup but with your batteries. Rechargeable AA batteries only come in 1.2V, changing your 4 cells into a 4.8V cell not a 6V as your calculations show. Adjusting for this with your resistor value could possibly allow for brighter LED. Must say i like the concept. I would like a electric bell that's loud! Maybe when i have time Link to comment Share on other sites More sharing options...
wazi Posted March 5, 2015 Share I am pretty sure you made a mistake there. Not with your calculations or setup but with your batteries. Rechargeable AA batteries only come in 1.2V, changing your 4 cells into a 4.8V cell not a 6V as your calculations show. Adjusting for this with your resistor value could possibly allow for brighter LED. Must say i like the concept. I would like a electric bell that's loud! Maybe when i have time You have a point. I wonder what difference it would make. What reflector/lens are you going to use with the LEDs?That's quite a significant factor in the quality/usability of the light output.Im using lenses from Rabtron but I think they could be better. Link to comment Share on other sites More sharing options...
wazi Posted March 10, 2015 Share Build PART TWO Resistor PairI soldered the two resistors together. One for each LED. I bound them with heatshrink. SwitchesI decided to use some old water bottles to house the batteries and switches. Even new bottles were a cheaper option than any others that I looked at. I cut out the center nipple for the main switch. Drilled two additional holes, one for the flasher switch and one for the wires. Wiring the switches And that's it! The actual lights were mounted on a 20mm aluminium flat bar. I drilled two holes at the bottom and just cable tied it to the handle bars. Will post some pics of the lights at night later on. Link to comment Share on other sites More sharing options...
the nerd Posted March 21, 2015 Share I want an update [emoji2] [emoji2] Link to comment Share on other sites More sharing options...
Pulse Posted March 22, 2015 Share I want an update [emoji2] [emoji2]Yes please! :-D Link to comment Share on other sites More sharing options...
Brian Fantana Posted March 22, 2015 Share Just note that using a resistor to "control" the current is only effective in a constant voltage system. In a typical cycle light powered by battery application you can have a voltage drop from 8.4V to 7.4V over the battery runtime. You need to check the light output vs current graph, but your light output will drop as the voltage drops. This is why a constant current driver works well for a battery powered light. Here is my DIY light, it runs on a 8,4V battery, with a light output of 600 lumens. I have been using it on all my morning and night rides since mid 2011. It was made with locally sourced components. I have another one (1000 lumens) with stronger LED's which I got from Cutter LED in Melbourne: Link to comment Share on other sites More sharing options...
Brian Fantana Posted March 22, 2015 Share Very neat work by the way! Link to comment Share on other sites More sharing options...
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