Off Piste (non A7 related matters)

[Reckless Rat]

Can anyone help. A mate has given me a pair of 12v US sealed beam headlights from his E type project, one of which I propose to use to replace the burnt out sealed beam in my pool underwater light. Looking at the back of the unit the three blade terminals are arranged in a 'U' shape and I want to use the main beam. I am guessing that the centre terminal is common/earth and the other two are Main & Dip respectively, but which one is the main beam?

The underwater light is a sealed affair so there's no water interface, and it has a 12v DC supply.

Any ideas? I've tried doing it with crocodile cips but all I manage to do is dazzle myself!

It's like this: (library photo)

[Tiger]

I would have a look at the Wattage of the burnt out unit.
Your 12 V supply may cope with either
You could wire both if appropriate supply but this may too much.

Further idea cover the sealed beam with thick cloth you should see the difference
Don’t let the material get too hot

[jpsmit]

Looks like the ground is not the centre. For a pool I suspect main beam is enough but I suppose it depends on whether you are wearing a cossie or not.

Here is the diagram:

https://mgaguru.com/mgtech/electric/et135.htm

[Colin Morgan]

I was checking my lights and which was full beam and which dipped on my car in the garage late last night - turned out I had left the headlights on dipped. Seemed I could still see the images on my retina this morning.

Suggest pointing it at something vaguely shiny in the middle distance - 8m - car door or garage door or smoked glass - and looking at either the reflection or 'spot' generated.

Or put 6v across it - then you won't be dazzled. Or look at the filaments through gas-welding goggles. Or measure the current - 50 watts is just over 4 amps, 36 watts about 3?

[Reckless Rat]

Thanks for that link. I will try that configuration! There are two wires to the existing lamp so I doubt that polarity will be an issue.

[dickie65]

Dipped beam will aim lower and to the left in the UK or right in the USA and be slightly lower watts

[jpsmit]

I might also add that while this is a quick and easy solution that LED lights are astonishing and amazingly inexpensive - going for a colour or a colour changing bulb could be a nice option as well.

[Reckless Rat]

I have looked at an LED replacement, but apart from the cheapie floating versions from the far East, an LED replacement conforming to EU standards isn't that cheap ( of whatever provenance). They are selling for around 60-70€ on Amazon.

It's a possibility but I'll see if the sealed beam does the job, as if I'm honest, it won't get much use anyway.

[bob46320]

From the net
"In electronics, polarity indicates whether a circuit component is symmetric or not. LEDs, being diodes, will only allow current to flow in one direction. And when there's no current-flow, there's no light. Luckily, this also means that you can't break an LED by plugging it in backwards."

Connect and try it - BUT I take no responsibility

[Reckless Rat]

Thanks for all your comments everyone. I spent three hours changing over the lamp, having to replace the wiring behind it because of corrosion and then discovered that the 220v to 12v transformer had burnt out as well so no supply. The bloody water was cold too. Sod it.