Dragonfly Lighting/ignition switch.

[Les Mills]

I intend substituting a Lucas PLC5 switch.  Does anyone please have a wiring diagram, I have a solid state rectifier and don't need the complication of  emergency start.  In the same vein, has anyone fitted a "battery condition light"?  I saw one on Paul Goff's sight and they seem like a good idea.

                                     Regards,
                                                          Les

[Les Mills]

Should have done a search first.  Have just seen Eddie's reply to BrmBrm on 25th Feb 2013.  It appears I am stuck with the old Miller, however the Ignition part is busted, any ideas.

                                Regards,
                                                Les

[charlie weeks]

Les

Lucas and Miller alternators are wired the same, i.e. one pair of coils are wired together and the remaining two pairs are wired together. The single pair are coloured yellow according to Miller diagram 2166 and the two pairs together are coloured green. Both go the Miller switch with the remaining common brown to the rectifier.
In Lucas arrangements it is the green/white that is common and that, along with the single pair of coils wired green/black that goes to the rectifier with the two pair yellow/green that goes to the switch.

I strongly recommend that you get a copy of Bernal Osborne's Motor Cycling Electrical manual and a copy of diagram 2166 but you CAN use a Lucas switch if you wire up to the Lucas configuration. You won't have six positions but your bike will work satisfactorily using the Lucas switch.

Charlie

[charlie weeks]

Sorry Les

Copied the wrong wiring diagram. The eyes aren't what they were !

Regards

Charlie

[Les Mills]

Hello Charlie,
                         Many thanks for your speedy reply.  The Lucas option seems far easier to follow, I think I will go for that.  I reckon mine was wrongly wired as a very healthy charge was showing all of the time which makes me think all of the coils were always in use, hence me considerring a Paul Goff battery condition light.

                          I do have a copy of "MotorCycling electrical manual" which I often refer to, but it is a 1960 edition and doesn't have that diagram!  Thanks also for your explanation which a non tequi like me could cope with.

                               Regards,
                                                 Les

[charlie weeks]

Les

The Lucas switch does not have any provision for running the red spot on your ammeter which is a good thing ! The red spot seemed to be a fashion accessory during the Fifties and is totally unnecessary. If the bulb blew or simply came loose, no ignition. Wonderful !
If you must have it I suggest it goes between the number 14 terminal on the switch and the coil but bulb failure will have the same results.
The Lucas PRS8 switches all seem to be made in India. What a shame they haven't got round to a bandit Miller 6 position one. Our type is similar but not the same as that used on Miller LE's and Valiants but with the ninth terminal although they could use ours. If you are going to change to Lucas why not go 12 volt as well. With the addition of a Zener diode I'm sure it is what the Dragonfly would have ended up with had it lived long enough especially with the demise of Millers in the mid Sixties. ( and the emergency start position should still be operable)

Charlie

Charlie
 

[eddie]

Les/Charlie,
                  If the Miller system is wired correctly, the red warning light is a 2.5 volt bulb wired in parallel with a ballast resistor, so that the ignition will still work should the bulb fail.

     Regards,
                   Eddie.

[charlie weeks]

Eddie

Have just had a look at my red spot bulb holder and discovered a tiny break in the wiring which explains why my ignition stopped working with a bulb failure. Still don't think much of the idea though !. Do you know the value of the ballast resistor ?

regards

Charlie   

[Les Mills]

Hello Charlie and Eddie,
                                        Many thanks for your replies.  If I go for 12v would the Zener Diode help control the charge rate?  I always feared I was cooking the battery.

                                             Best regards,
                                                                            Les

[eddie]

Les,
       Yes, you will need some form of voltage regulation when converting to 12 volt. When I built my 4 cylinder special, I used a Miller alternator from a Dragonfly and wired it for 12 volt - on start up, it gives 8 amps charge - that's 96 watts from a unit that was only rated at 60 watts when new! The main drawback with either a Lucas or Miller alternator when wired for full output is that there is no internal regulation of the output, so full output is generated and then some is wasted by the regulator (Zener diode or whatever). Even though that energy is wasted, it had to be produced in the first place, so that energy is no longer available for propelling the machine.

  Regards,
                Eddie.

[charlie weeks]

Les

The earlier zener diodes could only handle a maximum of 5 amps. I do not know what those on sale at the moment will safely carry. If you retain the Miller 3 wire alternator or swap for a 120W 3 wire "Lucas" type you should be ok as the full output is only available with headlamp running, So 55W on dipped and say 25W for the igniton plus some for rear and speedo light leaves you well within the safety margin. Worth also changing your rectifier at this point.
If you decide you want more output then it's two zeners in parallel or a modern day regulator. Remember to get the correct polarity zener and rectifier and you may also need to make mods to your wiring to got from 2 wires to the switch and one to the rectifer as current Miller to 2 wires to the rectifier/regulator and one to the switch for any later set-up that you choose.

regards

Charlie

[Les Mills]

Thanks Eddie and Charlie,
                                             That gives me lots to think about, still, the non-riding bit of the season is with us!

                                                    Best regards,
                                                                                 Les