k80rum Posted June 18, 2007 Share Posted June 18, 2007 With all the other jobs I'm doing, I don't really have the funds left for a decent, multi-light, shift-light system (especially not a drool-worthy one like the Sureshift)... But I've been thinking I could wire up a 'shift soon' light to the Stack output in addition to my standard, red 'shift now' light which is triggered by the Emerald as this would give me an improvement on my current setup for only the cost an ultrabright LED. My problem is that I don't know what kind of LED to get. The Stack will drive up to 2w - I don't know whether the output runs at 5v or 12v though Maplin seem to have a fairly healthy stock of LEDs, but I'm struggling to know whether I need a 5v or 12v one, how bright I should be looking for, and whether it'll fall beneath my 2w limitation. If anyone's fitted their own shiftlight to a Stack before, I'd be very grateful if they could point me in the right direction. TIA Darren E Website K80RUM and Emerald maps library Superlight R #54 Link to comment Share on other sites More sharing options...
Colin Mill Posted June 19, 2007 Share Posted June 19, 2007 While there are some LEDs with built-in resistors most don't. Depending on the colour the voltage drop across a LED is typically 1.8v to 2v. 20mA through most LEDs gives you a pretty bright light so if the output of the unit is 5v you will need about a 150 ohm resistor in series with the LED to set the current. If the output of the unit is 12v then you will need a 560 ohm resistor to set the current. 2 watts at 12v is a current of 167mA so there is no problem about exceeding the 2 watt drive capability. Colin Link to comment Share on other sites More sharing options...
k80rum Posted June 20, 2007 Author Share Posted June 20, 2007 Many thanks Colin. One LED (&resistors) duly ordered! Darren E Website and Emerald maps library Superlight R #54 Link to comment Share on other sites More sharing options...
Colin Mill Posted June 20, 2007 Share Posted June 20, 2007 Hi Darren If you find it difficult to hit a brightness compromise that works OK day and night let me know - I think it would be fairly easy to make a little circuit that dimmed it for night time use. Colin Link to comment Share on other sites More sharing options...
k80rum Posted June 20, 2007 Author Share Posted June 20, 2007 Thankyou Colin, that's really kind . I'll keep you posted. Darren E Website and Emerald maps library Superlight R #54 Link to comment Share on other sites More sharing options...
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