Reverse protection for EverLED

[Khaytsus]

I have enough electronics knowledge that I probably shouldn't be asking this dumb question, but here goes..

I know that if they put a diode in the front of the circuit it would raise the minimum input voltage which is obviously unwanted, but why couldn't they put it after the booster circuit, since it's the LED and (presumably?) not the booster circuit that is damaged by reverse polarity.

This would lower efficiency, but the minimum input voltage would be the same and would offer protection to the light.

Any problems with this idea? I know space is at a premium, but it'd be great if that slip of paper that came with the bulb said "If light does not function, ensure positive-tip polarity." rather than "Reverse polarity may (will) damage light"

 

[The_LED_Museum]

I'm guessing that both the circuit *and* the LED let out their supply of magic smoke at the same time. Having a diode that protects the LED would not protect the circuit itself, so you might still smoke it.

Something prominent that reads "DANGER! Reverse polarity will smoke your EverLED and void its warranty!!!" would be better than the slip you got.

I've never tested this bulb though, so I have no first-hand experience with it.

 

[Empath]

Since they do target the inexperienced, a stronger worded warning would be advisable. However, beyond that warning I don't see any responsibility on the part of the manufacturer requiring them to make it foolproof. Proper polarity and the avoidance of static charge should be assumed when working with susceptible components. Still, since they target the inexperienced, proper warning is essential.

 

[Doug Owen]

[ QUOTE ]
The LED Museum said:
I'm guessing that both the circuit *and* the LED let out their supply of magic smoke at the same time. Having a diode that protects the LED would not protect the circuit itself, so you might still smoke it.


[/ QUOTE ]

Actually, I bet the LED itself is fine.

It would seem entirely possible to blow the EverLED up on two cells backwards (3 Volts total), a voltage all but a very few diodes of any type will tolerate 'backwards'. The specs for the Luxeon in fact guarantee 'greater than 5 Volts' for reverse voltage. This alone means it should be 'impossible' to kill it with even a four cell light.

The circuit is another matter entirely. Since it must run down under a Volt design limitations make protection difficult. My money says the LED still works, although you might have to cut one lead free to remove 'failed to short' circuits inside. The magic smoke is still safe.

FWIW some low drop out series regulators (like Mr Al's 334 based one) are safe from reverse voltage for reasonable voltages without any loss of efficiency. No extra diodes (with their loss) needed.

Cheers.

Doug Owen