No resistor(s) in Trek 7?

[Gandalf]

I have been meaning to ask this question since I found this forum. My Trek 7 (C.Crane)
has no circuitry to regulate the current: just 7 white LED's on a piece of circuit board. Why don't these LED's burn out, with the full power of 3 C cells running into them? No resisters, nothing. Seems to work OK, but what am I missing here (due to ignorance, I assume.)

 

[geepondy]

I guess the internal resistance of the batteries is sufficient. Lots of LED lights seem to be this way including the photon. Sure makes for lousy regulation though. Lots of people will sing the accolades(sp?) of the Trek 7 but I think it's a very crude design. It is rugged and basically effective in it's purpose but I would expect more refinement for a light of that cost.

 

[The_LED_Museum]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Gandalf:
I have been meaning to ask this question since I found this forum. My Trek 7 (C.Crane)
has no circuitry to regulate the current: just 7 white LED's on a piece of circuit board. Why don't these LED's burn out, with the full power of 3 C cells running into them? No resisters, nothing. Seems to work OK, but what am I missing here (due to ignorance, I assume.)

<HR></BLOCKQUOTE>

The LEDs don't go "POW!" with a bang and a stinky puff of smoke because none of them receive a fatal dose of current.
With 7 of them in parallel, each one gets 60-something milliamps, which is just a bit below the fatal level. Whatever 7*60 is, would be the total drain on the batteries.

Apparently, alkaline "C" cells cannot deliver - constantly - a fatal current to the series (around 500mA continuous) which is why the LEDs don't get smoked.

After several sets of batteries though, you will notice them dimmer than they used to be, especially if you compare your well-used Trek-7 to a brand spanking new one.

It might not be much, but if you look carefully, you may be able to see the difference.

 

[KenBar]

I also found the same thing...I returned mine after the lens broke and CCrane replaced it with a new one. It was MUCH brighter. I had been through quite a few batteries with it...1.5 years

 

[The_LED_Museum]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by KenBar:
I also found the same thing...I returned mine after the lens broke and CCrane replaced it with a new one. It was MUCH brighter. I had been through quite a few batteries with it...1.5 years<HR></BLOCKQUOTE>

If you had yours for that long, it wasn't the LEDs degrading that made the difference - it was that the newer model you got used a BETTER version of the LED.

N.B.
There are anecdotal reports that the newer generation of Nichia LEDs can handle higher currents better than the older type, so the degredation from overcurrent may occur much more slowly now.

 

[PeLu]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Stingmon:
If you had yours for that long, it wasn't the LEDs degrading that made the difference - it was that the newer model you got used a BETTER version of the LED.

<HR></BLOCKQUOTE>

It may be both. I have one of the first ActionLights and have plenty of occasions to compare it to newer ones. The difference is in many ways big.
But driving a white Nichia LED with 60mA w/o a sufficient heatsink will damage the phosphor in less than 100 hours.