Which bayonet type is this?

[Barry White]

led 2 and 3 are dual fillament stop and tail bulbs (well dual led) the negative to the outer metal case and positive to either or both pins on the base to illuminate the bulb either dim or bright or even both sets.
suspect led 1 is the same but carnt be sure with the info supplied.

 

[mascip]

I'm guessing I won't find a LED that suits this lamp socket, so I should just get a new socket, probably. Or in this case, a new navigation light.

Thanks for your help

 

[Barry White]

you will get a led a quick search of ebay produces these 2x MG TRIUMPH JAGUAR AUSTIN HEALEY MORGAN LED BULBS GLB209 BA15D 5W BAYONET | eBay
depends on how bright you need them at a guess these are equivalent to a 5w incandesent lamp.

 

[mascip]

What is the difference is between these light bulbs and the ones I bought? Does GLB209 mean that the negative connects through the second contact at the bottom?

 

[Barry White]

Older bayonet bulbs were double contact and powered the the fillament through just the pins and polarity did not matter. later bulbs used single pin and the"outer can" to power the bulb. Then along came the dual fillament bulb (used for the stop and tail lights on cars) its basically 2 bulbs in one so each pin powers up an individual fillament using the outer can as a return.
some leds are polarity conscious if so just insert and if it dont work turn it around 180 degrees and reinsert.

the bulbs you bought are 2 bulbs in one used for stop and tail on cars the description is written in chinese then changed to english and hence the confusion both bulb types have the same size and number of pins.The pins are just connected differently.

 

[mascip]

Very clear explanation, thank you!

"Double contact" is the key word I needed to find the appropriate LED bulb. Great!

 

[Marvo]

Re: Reported Post by darkwood

If it's a single filament BA15D and the bayonet pins aren't at different heights then the holder (base) will obviously accept the lamp in two possible directions.

With an old fashioned filament lamp this wasn't a problem because it would work equally well in both directions. With new LED type lamps polarity is a big issue, it will only work one way around in the fitting and it could be damaged the other way around.

It's very possible you've already damaged the lamp already by accident so test it on a bench with a battery first. Then you'd need to establish which side of the lamp holder is positive and preferably mark it so you can ensure when the lamp is inserted its positive side is in contact with the positive side of the lamp holder before putting power on it.

 

[Richard Burns]

Lamp designations are like this

B a 15 d
Bulb, all purpose shape, 15mm diameter, double contact
also known as SBC small bayonet cap

B A 15 s
single contact
also known as SCC single centre contact

B a u 15 s
120° off set pins single contact
B a y 15 d
different height pins double contact double filament (can be single filament)
B a z 15 d
120° off set pins double contact double filament

However some manufacturers are a bit lax about this and may not specify correctly.

You were originally correct with the bulb designation, the supplier was not.

 

[BroadReach]

Please bear in mind if this is for use in a boat Nav Light, the filament used in old nav lights were specially designed for a pin point source. i.e. the filament is in a straight line up and down not curled round like a domestic lamp.

This is required to ensure the light is only visible through the correct angle of view.

Normal LED replacement bulbs may not give the correct light pattern.

 

[Marvo]

Please bear in mind if this is for use in a boat Nav Light, the filament used in old nav lights were specially designed for a pin point source. i.e. the filament is in a straight line up and down not curled round like a domestic lamp.

This is required to ensure the light is only visible through the correct angle of view.

Normal LED replacement bulbs may not give the correct light pattern.

Good point, some of those old navigation lights had a coloured fresnel type lenses in which case the exact position of the light source would be critical.