Bulb ID

[Harry Bloomfield]

The pins are symmetrical - how can they guarantee polarity?

The tiny little diagram - that d version, is not the version they are offering for sale on that page, the diagram is just for the customer to be able to identify the type of pin base. No doubt, somewhere on the site, they will offer the d version, but that page is not it.

How can they guarantee polarity - they cannot. The LED is diode protected against reverse polarity. You just fit the lamp, and test it - no worky, swap it round with the pins the other way. I have a dozen such lamps, less than a yard away from my elbow, at the present moment.

 

[JohnW2]

How can they guarantee polarity - they cannot. The LED is diode protected against reverse polarity. You just fit the lamp, and test it - no worky, swap it round with the pins the other way.

With one 'protection diode' that would be true. With four diodes (aka a 'bridge rectifier') the lamp would work regardless of the polarity of electricity applied to its pins.

 

[morqthana]

Why not just connect the LEDs in a bridge arrangement?

OK, only half would light up, but if that's expected...

 

[Harry Bloomfield]

Why not just connect the LEDs in a bridge arrangement?

OK, only half would light up, but if that's expected...

Diode, is cheaper than half the cost of the LED's being none functional.

 

[JohnW2]

Why not just connect the LEDs in a bridge arrangement?

Do many LEDs not have very low maximum reverse voltages?

As I wrote, if one feeds the LEDs via a separate 'bridge rectifier' (just four diodes but, in practice, probably just a single package) then all the LEDs will light up regardless of the polarity of the supply.

 

[morqthana]

Do many LEDs not have very low maximum reverse voltages?

Put 2 or 3 in series on each side.

As I wrote, if one feeds the LEDs via a separate 'bridge rectifier' (just four diodes but, in practice, probably just a single package) then all the LEDs will light up regardless of the polarity of the supply.

Is it six-of-one-half-a-dozen-of-the-other re cost & complexity?

 

[JohnW2]

Put 2 or 3 in series on each side.

That would help, provided that the reverse voltage ended up being reasonably equally shared between the LEDs. However, you will still be stuck with the fact that you will have to install (and 'pay for') twice as many LEDs to get the same light output as when all it together.

Is it six-of-one-half-a-dozen-of-the-other re cost & complexity?

Per the above, I imagine that the cost of a very-low-current bridge rectifier (probably negligible 'in bulk') would be less than the cost of having to use twice as many LED elements, wouldn't it?

 

[SUNRAY]

Put 2 or 3 in series on each side.




Is it six-of-one-half-a-dozen-of-the-other re cost & complexity?

8 additional bulky LEDs could significantly increase the size of the unit Vs a tiny bridge rectifier.