Led bulb replacement

[emoreira]

I have a Technisub Lumen X6 dive torch with incandescent bulb (LUMEN X4 - LUMEN X6)
I replaced the original incandescent bulb with a LED Bulb TTS 1 Watt CREE XPE LED Torch Bulb from The Torch Site (TTS-1WCREE 1 Watt Cree LED Torch Bulb Upgrade 2 to 9 Volts).

All dive torchs I have handy have negative central pin, while on-land general purpose torchs have positive central pin.

Any idea why this difference ?

 

[3D diver]

It doesn't matter which direction the current flows through an incandescent bulb but an LED is a diode so normally conducts in only one direction. That explains why the polarity is important in an LED system, but doesn't explain why the system design changed.

If what you say is true, I'm guessing someone designed an LED system that way, ignoring the established configuration, and that design got locked in as an industry standard before anyone questioned the change. Engineers (and I am one) redesign the wheel all the time.

Oh, and FWIW:the LED flashlights and dive lights I own have the same battery orientation as incandescents---i.e. positive to the LED module, negative to the light barrel.

Thinking about this some more...

In an LED system there is typically a control/regulation board between the battery and the light board itself. The polarity design is likely related to how the LED itself is switched by the controller, i.e. lowside switching (transistor between the LED and ground) or high side switching (LED between the transistor and ground).

Are you aware of this forum?

CandlePowerForums

If you want to go deep into such nerdly topics, that's the place.