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* LEDs: £10 (£0.66p per LED from [http://www.powerledworld.com/en/50pcs-x-high-power-warm-white-3w-110lm-led-super-bright-3watt-light.html PowerLedWorld]) | * LEDs: £10 (£0.66p per LED from [http://www.powerledworld.com/en/50pcs-x-high-power-warm-white-3w-110lm-led-super-bright-3watt-light.html PowerLedWorld]) | ||
* | * DC-DC switching converter: £2.49 (from [http://www.ebay.com/itm/321439418999?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT ebay]) | ||
* 50W laptop supply: £0 as we have a few downstairs (need to count how many we have!) | * 50W laptop supply: £0 as we have a few downstairs (need to count how many we have!) | ||
* Galvanised Steel Channel: £6 per 2.4m (from [http://www.diy.com/departments/gypframe-galvanised-steel-stud-l2400mm-w4545/119407_BQ.prd B&Q]) | * Galvanised Steel Channel: £6 per 2.4m (from [http://www.diy.com/departments/gypframe-galvanised-steel-stud-l2400mm-w4545/119407_BQ.prd B&Q]) | ||
Total cost: ~ | Total cost: ~ £18.50 (to compare 8ft 100W fluorescent tube only, no fittings! costs £15.59 on [http://www.lampshoponline.com/f100w-t12-fluorescent-tube-8ft-100w/ LampsOnline]) | ||
=== Implementation === | === Implementation === | ||
At 3.5V each LED consumes around 750ma. 5 LEDs in series would need 17.5V across them. We need 3 of these arrays to make up 15 meaning that we have a current draw of 2.25A for a total of 39.375W. Which is well within what even my weak 60W X220 thinkpad PSU can deliver. | At 3.5V each LED consumes around 750ma. 5 LEDs in series would need 17.5V across them. We need 3 of these arrays to make up 15 meaning that we have a current draw of 2.25A for a total of 39.375W. Which is well within what even my weak 60W X220 thinkpad PSU can deliver. |