Hi Bob Larson, Bob Spindell and List,
First, I know absolutely nothing about the electrics and doubt I could
hold a decent conversation with either of you to Bob's! :-(
I use a homemade display case with three Lucas bulb sockets for my "show
and tell". The sockets hold a tungsten, halogen and LED bulb for
comparison. It's powered by my 12V battery charger. I had no problems
leaving the bulbs on both low and high brightness for extended periods.
When asked about the positive ground, I sacrificed one bulb by putting
the charger's positive clamp on the outer (ground) section and touched
the bottom electrode with the negative clamp. It went puff and let the
smoke out.
I anticipate being told that my charger was putting out more than 12V.
OK, if that's the case, why didn't it blow the LED in the comparison? I
don't have too many friends with Healeys that are still positive ground
but I'll try to quickly find one for a true test. Until such time I
will stand by my negative ground only warning.
I hope everyone's turkey is/was moist and tasty!
Bill
Red Car Enterprises
Bob Spidell wrote:
> re: "Hook them up the other way and in about two seconds you'll get a
> flash and a small amount of smoke being let out of the bulb."
>
>
> That doesn't make sense. LEDs are diodes ("light emitting") and when
> reverse-biased will just block current flow; i.e. nothing will happen
> (they won't light up). If their rated voltage is
> exceeded--presumably, they're rated for 12V or more--they'll be
> destroyed regardless of which way they're wired. Maybe there's other
> components in these kits that could fry if reverse-biased, but a diode
> won't (if the diodes are 5V there's probably some resistors to reduce
> voltage, but resistors don't care which way the current is going).
>
> If they're in a socket plug--like a bulb--then just switching the
> internal leads for ground and power--if it's possible to get to
> them--would allow them to work in a pos. ground car (as long as
> there's nothing else 'hot' that could be grounded).
>
> Happy Thanksgiving all,
>
> bs
>>
>> First, there is a very big warning: All LED's that I know of are
>> NEGATIVE GROUND ONLY! Hook them up the other way and in about two
>> seconds you'll get a flash and a small amount of smoke being let out of
>> the bulb.
_______________________________________________
Support Team.Net http://www.team.net/donate.html
Healeys@autox.team.net
http://autox.team.net/mailman/listinfo/healeys
http://www.team.net/archive
|