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OD switch as Dimmer

steveg said:
Hello listers,
In the 'Dead pedal' discussion it was mentioned the OD switch can be used as a dimmer.

Can it handle the headlight current or does it need a relay?

:savewave: Relay be very nice then existing OD switch can be retained.--- :thumbsup: Dead Petal article utilised a 35 amp switch---Keoke
 
I authored the Dead Pedal thread and said I was going to use a 35 amp switch, as was already pointed out.....which I'm still planning on doing... but now I think I'll be using it with a relay. Why? The switch I picked was a single pole single throw which is problematic as a substitue for the Healey headlights, i.e. the foot dimmer is more like a single pole double throw since it shuts off the low beams when you turn on the high beams. The single pole single throw would leave the low beams on when the high beams were turned on. I don't know of a reason that would be a problem but to replicate the original, i.e. turning off the low beams when turning on the high beams.... I will need to use a relay if I want to use the switch I have. Since I like the feel of the switch I have.... low effort, nice action... I'm going with a relay. You could skip the extra relay by using a single pole double throw switch for the dimmer.

Cheers,
Steve
 
A relay is always a good idea (and was originally incorporated in the circuit) as any type of solenoid can do a lot of damage to the entire circuit, if it goes south.

When building electrical control panels (my livelyhood for a few decades) I would always used fused terminals for solenoid valves, even though the circuit already had one or more relays in it. I learned from the experience of NOT using fused terminals (even though there was plenty of short-circuit/over-current protection).
 
If you want to put the finishing touch on this conversion of your OD switch to a "Head lamp dip switch" as the folks across the pond used to call it I know what you need. I recently found out that XKE's had a dash mounted toggle switch for the "dip" switch....and, of course, there is a escutcheon that states the use of the switch so I just had to get one....pic below
 

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