Using LED as indicator warning light.

[pkboxer]

It tells me I need a 1 Ohm resistor....

Safety first!

[barryh]

At a guess you entered the current in amps instead of milliamps. i.e 0.020 instead of 20
The calculator is already configured to divide the current by 1000.

[Rob Frankham]

Interesting post... actually, there are a number of ways to do this. I've very quickly worked up a series of 4 circuit diagrams showing different ways. Which you choose depends to a certain extent on which sort of indicator relay your bike uses.

indicator repeater.jpg (172.71 KiB) Viewed 1079 times

Brown lines represent ground wires, black lines the other wires. If you use the bicolour4 or multicolour LEDs, you'll have twoo different coloured lights in the same housing... one for left and one for right which is cool (if a bit pointless).

Hope they make some sort of sense...

Rob

[Major Softie]

Rob, if one wanted separate L and R indicator lamps, could you just hook them between the two grounds - one one direction and the other the other? I'm wondering if the LED's use little enough current that they would light up with such a trickle off the ground when that circuit was turned on. A meter would be able to read voltage across those wires, but I don't know nearly enough about electronics to know if there would be enough current traveling through the LED to light it up when it had a clear path to ground as an alternative. I do know that being downstream of the signal lamp would allow that signal lamp to provide the resistance that the LED needs to limit its current.

[Rob Frankham]

Rob, if one wanted separate L and R indicator lamps, could you just hook them between the two grounds - one one direction and the other the other? I'm wondering if the LED's use little enough current that they would light up with such a trickle off the ground when that circuit was turned on. A meter would be able to read voltage across those wires, but I don't know nearly enough about electronics to know if there would be enough current traveling through the LED to light it up when it had a clear path to ground as an alternative. I do know that being downstream of the signal lamp would allow that signal lamp to provide the resistance that the LED needs to limit its current.

Hi MS,

The short answer is No. There wouldn't (read shouldn't) be enough voltage between the two grounds to light the LED. In fact, and in principle, there shouldn't be any measurable voltage between the two grounds. If there is, it implies that you have a 'high' resistance connection in your ground lines. In practice, wires and connections not being 100% resistance free, you may be able to measure a very small voltage at this point but nowhere enough to light a LED.

Of course, if it's two indicators you want, you can just wire them in parallel with the two indicator circuits (using the requisite resistors of course.

One other thing I should have mentioned is that you can get LEDs sold as 12 volt LEDs. These are nothing more than ordinary LEDs with integral resistors. If you can get these, you don't have to bother with the seperate resistors.

Rob