# bit-tech.net

 bit-tech.net Forums CPC Issue 110 - Temperature Sensor Correction
 User Name Remember Me? Password
 Register FAQ / Rules Calendar Search Today's Posts Mark Forums Read

 19th Sep 2012, 11:25 #1 Gareth Halfacree WIIGII! bit-tech Staff     Join Date: Dec 2007 Location: Bradford, UK Posts: 1,826 CPC Issue 110 - Temperature Sensor Correction Reader John Knight has written in with a criticism of my Arduino-powered temperature-sensitive LED controller on page 110 of - oddly enough - issue 110, stating that my calculation for working out the value of current-limiting resistor required for a given LED in step 3 is absolute gibberish. Do you know what? He's completely right. When writing the article, I apparently had a brainfart and wrote the equation as R=(Vs x Vf)/I rather than R=(Vs-Vf)/I. That wouldn't have been *too* bad, if when writing the instructions to go with said equation I hadn't based them on the typo'd version. Mea maxima culpa. If you're curious, this is how step 3 *would* have read had I not apparently been asleep on the job: If you’re using the recommended RGB LEDs from open-source hardware specialist www.oomlout.co.uk, you can skip this step, as the correct resistors are provided. If not, use the formula R=(Vs-Vf)/I, where the resistance, R, is calculated by subtracting the LED’s forward voltage drop from the source voltage – 5V – and dividing the result by the LED’s rated current in amps. For most RGB LEDs, this works out at 270 Ohms. There'll be a correction printed in next month's CPC, Ben tells me. In the meantime, accept my humble apologies, dear readers. __________________ Co-author, Raspberry Pi User Guide, Meet the Raspberry Pi | gareth.halfacree.co.uk | twitter bit-tech news correspondent, Custom PC columnist I'm a filthy freelancer! Hire me!
 13th Oct 2012, 14:50 #2 NethLyn Hypermodder     Join Date: Apr 2009 Location: London Posts: 918 Fast correction; the benefit of subscribers I'll just hijack this thread to say that the PSU Labs is as good as always, as one of the two guaranteed issues I buy off the shelf each time there's a labs. If the GPU labs is definitely in next month's, that'll be the other one. __________________ Intel=Fast, AMD=Cheap.
 14th Oct 2012, 00:59 #3 Kovoet Do I or Don't I     Join Date: Aug 2009 Location: London, Harrow Posts: 4,390 Must be a northern thing lol. Thanks for letting us know in advance __________________ [Coolermaster Cosmos II] [i7 i2700K] [Hydro H100i] [ASUS GTX680 DirectCUii Top] [16GB Corsair Vengeance 1600mhz] [Asus Sabertooth Z77] [Corsair AX850] [1 x 300gb VelociRaptor] [1 x 1TB samsung F3] [Dell U2312H & U2311HM] [Corsair K90] [Belkin (razer) N52te] [ASUS ROG Vulcan] [120GB Corsair pro SSD] [ Mushkin 120GB deluxe SSD Sata 3 ][Logitech G9x] [ASUS Xonar DX soundcard] Asus Nexus Tablet