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cb1rocket |
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cb1rocket World Chat Champion
Joined: 30 Jan 2010 Karma :
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Posted: 01:14 - 30 Dec 2017 Post subject: resistor wattages |
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forgive me but search on google keeps flagging as an error!
Anyway! The problem I have is the indicators flash too fast (yawn, yes i know!) and I need to fit resistors in parallel but at what wattage and what resistance?
What I want to know is ideally what wattage should the resistors be?
Working on one side of the original indicator setup.
Bulbs are 21w, therefore x 2 = 42w.
Leds are 2w, therefore x 2 = 4w
42w - 4 = 36w of unused power still needed to be pulled through the relay.
Assuming I have this right, the resistance of the resistors need to be=
R = V/I . We have volts which is at 12v (ok its about 13.5v when running, but to keep things simple we'll say 12v) but not current so we need = P = VxI. rearranged = I = P/V
Therefore 36w / 12v = 3 amps
Therefore resistor = R =V/I
Therefore 12 / 3 = 4 ohms.
My question is, the resistance sounds too low and what is the formula for power dissipation in watts for the resistor? ____________________ Honda H100S2 Rebuild - https://www.bikechatforums.com/viewtopic.php?t=253852 |
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temeluchus |
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temeluchus World Chat Champion
Joined: 01 Oct 2008 Karma :
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stinkwheel |
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stinkwheel Bovine Proctologist
Joined: 12 Jul 2004 Karma :
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Posted: 10:24 - 30 Dec 2017 Post subject: |
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I agree with teme. Adding resistors to an LED flasher to make the relay work seems totally fucked up, adds 4 extra componants, 8 extra joins and defeats the entire purpose of using LEDs in the first place (ie, low current draw).
So yes, get an electronic flasher relay, fit and forget. ____________________ “Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles. |
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Tankie |
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Tankie Crazy Courier
Joined: 24 Feb 2017 Karma :
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Islander |
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Islander World Chat Champion
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cb1rocket |
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cb1rocket World Chat Champion
Joined: 30 Jan 2010 Karma :
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Posted: 14:24 - 30 Dec 2017 Post subject: |
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Was really looking into understanding how to work out.
I know the led relay is the way to go but would like to learn the theory behind it. ____________________ Honda H100S2 Rebuild - https://www.bikechatforums.com/viewtopic.php?t=253852 |
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P. |
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P. Red Rocket
Joined: 14 Feb 2008 Karma :
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Posted: 14:28 - 30 Dec 2017 Post subject: |
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Theory - maybe 30 minutes of reading and understanding.
Clicking buy it on £1, 20 seconds.
I'm being paid 15 an hour. Is it really worth an extra £6.50 to know how it works, or do I just wanna get on with my day |
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Tankie |
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Tankie Crazy Courier
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cb1rocket |
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cb1rocket World Chat Champion
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Islander |
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Islander World Chat Champion
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temeluchus |
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temeluchus World Chat Champion
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lihp |
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lihp World Chat Champion
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Triton Thrasher |
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Triton Thrasher Could Be A Chat Bot
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Islander |
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Islander World Chat Champion
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lihp |
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lihp World Chat Champion
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Stalk Brolly Dolly
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bamt World Chat Champion
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janner_10 |
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janner_10 World Chat Champion
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ThatDippyTwat |
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ThatDippyTwat World Chat Champion
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stinkwheel |
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stinkwheel Bovine Proctologist
Joined: 12 Jul 2004 Karma :
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Posted: 11:44 - 03 Jan 2018 Post subject: |
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You can also fit one, larger resistor on the output from the flasher relay. The one labelled "L".
I did this years ago on a bike that kept popping those mini 21w flasher bulbs. I replaced them with 5W instrument panel bulbs (same size fitting, were just about bright enough) which worked but didn't then flash. My solution at the time was to fit a 21w bulb and holder in series with the L-wire on the flasher relay under the saddle where it couldn't be seen. Effectively a resistor.
That was a good 20 years ago though, before LED flashers were a thing. ____________________ “Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles. |
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Old Thread Alert!
The last post was made 6 years, 114 days ago. Instead of replying here, would creating a new thread be more useful? |
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