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Using an LED bulb to replace indicator flasher on dash.


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Hi All,

 

I recently purchased a LED bulb to replace the standard bulb used by the indicator flasher within the speedo on the dash, the idea being to have a brighter light that could be easily seen against daylight. Details of the bulbs I purchased can be found here but are 12v E10 MES bulbs.

 

I fitted the bulb and switched the right hand indicator switch and sure enough the LED bulb flashed and was much brighter, job done or so I thought. I then tried switching to left hand indicator but although the indicators themselves work nothing from the LED bulb, checked right hand again and it worked. I took the LED bulb out and replaced with the original and both left and right switch works and flashed the bulb. I checked the wiring to the bulb holder and all looks good. What could it be about the LED bulb that means it only works when switching to right-hand indicator?

 

 

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This is due to the way that the indicator is powered in the TR6. It's not like a normal lamp where one side is always earthy and the other side is powered. On the TR6 the polarity across the bulb changes according to which direction you are indicating. That's why, as you've found, a polarity conscious lamp like an LED will only light for one direction and not the other. To make it work you need to place a full wave bridge in front of the indicator lamp. Or put the filament lamp back. Or you could fit one of the combined LEDs and sounders which were for sale by a forum member on here. They include a full wave bridge.

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Led has + and - (diode)

bot not every LED works only in one direction.

Should be tested before use.

In the flasher the direction changes +/- to -/+

 

Those can also be obtained coloured and for main beam (blue)

and oil (green) but not suitable for alternator on TR6.

Edited by TriumphV8
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You can use LED for ign warning lamp, but you must solder a resistor across it to increase the "start up" field current.

I used a 220 ohm 1W one. (TR3 with alternator fitted)

 

 

 

 

Bob.

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Hi All,

 

Thanks for the replies, I can now understand how this will not work if the polarity changes across the LEB bulb changes. It looks like I need the full wave bridge referred to in Pete's posting, does anyone have details of part number or exact type I would need? Thanks.

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These will do it. Either

http://www.maplin.co.uk/p/kbpc104-2a-bridge-rectifier-aq99h

or

http://www.amazon.co.uk/2W10M-Single-Silicon-Bridge-Rectifier/dp/B0087YQPKU/ref=sr_1_12?ie=UTF8&qid=1416598079&sr=8-12&keywords=bridge+rectifier

 

The rectifier is marked +, -, and two sideways 's' pins

Connect the LED lamp centre contact to +, screw thread to - and the two wires from the loom to the other two pins marked with the 's' - polarity of those two does not matter. Make sure that neither end of the LED lamp is earthed - the lamp socket must be electrically 'floating'.

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Demon

There was an article in TR action (Technicalities) some years ago by John Wells that described a LED / Sounder modification. (Improved Traficator Operation)

Works a treat and its nice to hear that you have left your indicator on when blatting along.

Your may find a link in the forum.

John

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Hi,

Here is the link to a great YouTube video which shows you which parts to source and make this neat little piece of kit.

 

 

I have made a couple using one myself and it works a treat. The LED gives a much brighter light and of course you get the audible warning that indicator is still on when you make turns that do not engage self cancelling. The bridge rectifier is required for the reasons stated in the above responses to your post. Easy made and easy fitted without any mods to existing wiring.

 

A also managed to source components slightly smaller and lot cheaper than Maplins and RS from:- www.esr.co.uk

 

I also found that garden hose pipe (as well as the fuel pipe recommended in the video) is ideal to slide into speedo hole where the conventional bulb fits.

 

Hope it helps.

 

TonyC

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Hi All,

 

I managed to source all the parts from a local Maplins yesterday and built mine today, all works well and a blob of glue over the buzzer case hole reduces the volume of the buzzer to a reasonable level. Thanks again to all who provided advise and assistance.

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Hi Demon,

I've only just seen your PM and replied...glad that you have 'followed instructions' and got yourself sorted :)

(and thanks to Craig for taking over production............. ;) )

 

regards

john

Edited by johnny250
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