LED indicators

Hi Guy - I have fitted them to my Mk2a 1974 Commando - it was a bit of a fiddle. I bought the LEDs via ebay from China, they are not specific to Lucas bulb holders thus I hard-wired them into the indicator housing (this overcame any polarity issues). I appreciate that doing this makes replacement difficult but I've worked on the premise that LEDs seldom fail. I bought a special LED flasher unit but it didn't work very well (it seemed very voltage-sensitive) thus I reverted back to the standard flasher and put a 10ohm 25w resistor in parallel with one LED on each side of the bike (this 'loads-up' the flasher - without this resistor the LEDs don't draw enough current to flash). This works fine but I have to say that if I'd known how fiddly this all was I don't think I'd have bothered - they don't seem any brighter than normal bulbs but do give the typical LED abrupt 'flash'.

Hi Guy - firstly - that's two resistors - just one needed for each side of the bike.

Ref the warning light. I found that it would only flash when the left was selected. No light when indicating right. The reason is that the polarity applied to the LED warning light may 'reverse' when switching between left and right. The solution was to fit a full-wave rectifier (a small suitable unit only costs circa £1.00). Wire the supply to the 'AC' side of the rectifier and the LED to the DC side - with this in place the LED always get the 'right' polarity regardless of the supply.

Note that I have also fitted the same setup to my 1971 BSA Rocket 3 and I got exactly the same results as the Commando (they're both 12v +ive ground).

HtH

Mark.

Hi Guy - I tend to use Rapid Electronics for these types of bits - they have a good website - just Google Rapid Electronics. The part I'd suggest is under:

Electronic Components/Discrete Semiconductors/Bridge Rectifier Diodes

The actual part is 8amp 100v Bridge Rectifier Part number 47-2894. The cost is circa 50p ( the usual problem is then P&P which might cost up to £5.00 !).

Depending on where you live you may have a local Maplins or similar electronics retailer - all you're after is a bridge rectifier capable of 4 or more amps at 20 volts. (Currys etc. won't be any good for this type of thing.)

On my bikes I fitted the rectifier in the headlamp shell.

Most Bridge rectifiers have 4 wires - two will be marked with a ~ this is the input from the main bike electrics and it doesn't matter which wire is connected to the frame (+ earth) and the incoming negative (-) from the indicator circuit , the other two will be marked either + or - . The + will go to the frame (earth) and the - will go the the cathode (-) of the LED. Note that on most discrete LEDs the Cathode (-) has the shorter wire protruding from the case, the Anode (+) has the longer lead.

Hope this helps.

Cheers,

Mark Woodward

My mate has just solved this problem for a classic car he has. He broke an indicator bulb and soldered 2 LEDs in place but the opposite polarity to each other, so it didn't matter which way you were indicating, then super-glued the heads together. You don't have to change anything else then