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(Updated c-channel) |
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* DC-DC switching converter: £2.49 (from [http://www.ebay.com/itm/321439418999?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT ebay]) | * 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: | * Galvanised Steel C-Channel: £3.73 per 3m (from [http://www.builderdepot.co.uk/metal-c-stud-70mm-x-3000mm-x-0-55g.html?gclid=CjwKEAjwmfKpBRC8tb3Mh5rs23ASJACWy1QP-nSQJOg1NbD7UF-_spkwDjUkXLezUNNJhRVJeTvvyBoCdfbw_wcB Builder depot]) | ||
Total cost: ~ | Total cost: ~ £16.30 (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. |