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Old Sep 13th, 2017, 08:42   #46
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Last Online: Dec 9th, 2018 22:48
Join Date: May 2007
Location: Sheffield

Originally Posted by rtbcomp View Post
You don't have to buy a special flasher unit, just use a resistor to kid the indicator circuit it's got ordinary bulbs.

at 12v a 21w bulb takes 1.75 amps, 2 take 3.5 amps, so you need 3.4 Ohm 50Watt resistor. 3.3 or 3.9 ohm are the nearest preferred values. I'd go for the 3.9 (3R9) resistor as the LED lamps will still take some current.

If you can't get a resistor then connect 2 12v 21w bulbs in parallel
Further to what I've just said - you need a resistor for each side of the car.

On a 240 the indicators don't go through the bulb failure unit the above will work OK, for cars with more sophisticated electrics you may need a resistor of double the above values at each indicator lamp.

Another point to bear in mind is that if a LED bulb fails the flasher unit will still think there is a bulb in place, the flashing rate will be same so the driver won't be aware of bulb failure.
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