Author Topic: Dragonfly - Electrics- Ammeter- Insulated mounting Plate  (Read 131 times)

0 Members and 1 Guest are viewing this topic.

Offline BrmBrm

  • Full Member
  • **
  • Join Date: May 2012
  • Posts: 77
  • Location: North Wales
Last bit of wiring for the mo.
Thanks for everybodies help on this topic, and I've searched all the posts and seen the info. there.
I'm about to make the insulated plate that mounts on the ammeter.
My ammeter is not standard but I hope will do for now.

Looking at the wiring diagram I can see the wiring connections, ignition bulb, resistor.
Can't see an earth for the bulb, so is the bulb mounting earthed?
Are there any other earth or wiring connections not shown?
Is the insulated plate simply to mount the bulb bracket, and resistor?
Are the ammeter terminals connected to anything other than Term. 6 and Batt. Negative and Horn?
I can't see any reference to the Resistance of the resitor, does anybody know this?

Many thanks



Offline eddie

  • Master Member
  • ****
  • Join Date: Mar 2006
  • Posts: 1554
  • Location: Hampshire, UK
Re: Dragonfly - Electrics- Ammeter- Insulated mounting Plate
« Reply #1 on: 15 Jul 2020 at 11:41 »
Dave,
          The ignition warning light and ballast resistor unit have just the 2 wires connecting it to the main ignition switch (terminals 1&9). What isn't obvious from the wiring diagram is that the bulb is wired in parallel with the ballast resistor (so that a failed bulb doesn't kill the ignition). The bulb is screwed into the brass carrier which also acts as the former for the ballast resistor - so the wire from terminal 9 is connected directly to the outside of the bulb.
  There are no other wiring connections missing from the diagram.
  Yes, the insulator plate is just the mounting for the resistor/bulb unit - it is made of a heat resistant material, as it can get quite warm if the ignition is left turned on while the points are closed.
  One side of the ammeter should be connected to terminal 6 on the main switch. Both the horn and the battery should be connected to the other side of the ammeter (effectively connecting the horn directly to the battery, so that the ammeter doesn't have to take the relatively high load of the horn.
  Sorry, but I don't know the value of the ballast resistor, but an electrician should be able to work it out for you - the warning light being only 2.5 volt. If you are converting to 12 volt, you may have to recalculate the value of the resistor to maintain a voltage of 2.5 at the bulb.

  Regards,
                 Eddie.

Offline BrmBrm

  • Full Member
  • **
  • Join Date: May 2012
  • Posts: 77
  • Location: North Wales
Re: Dragonfly - Electrics- Ammeter- Insulated mounting Plate
« Reply #2 on: 15 Jul 2020 at 13:42 »
Thanks Eddie,
I could be wrong of course, but if it's like this, then :-
Bulb missing or failed as Open Circuit - Current still flows thru' resistor to Coil

To calculate resistance of the resistor I'd need to check the resistance of the bulb, so I need to get a bulb first. Anybody know the bulb Wattage?

Thanks for all your help.