dave walton wrote:
I've seen experienced electrical engineers make the same mistake, and
I've seen the companies they work for suffer because of having to live
with the consequences. If you are just playing around in your backyard
then toss in a series resistor. If it dies, you are out a few cents
and some time. Not a big deal. If you are designing a product for
sale, you might want to learn about the physics involved first. I've
been interested in LED lighting for a while and most of the
commercially available products ARE NOT engineered correctly.
LEDs do have average and peak current ratings... those ratings also have
a maximum duration, and maximum frequency the pulse can be repeated at.
There are also power dissipation ratings (one would think that the
current and power ratings would be the same, but I don't think that ever
happens)... I guess its because I've never seen those load-dump spikes
(not saying they don't happen, just never seen what they look like), but
I seem to think for most of us the LEDs and where we'd be using them in
the electrical system should be okay. I'm assuming there aren't any
major current consumption devices on the same fused branch as the
instrumentation lighting. So if the load dump current comes from
elsewhere (the glow plugs say) that 60V spike is going to have to make
it across all the inductance of the wire from the battery to the
instruments (assuming the battery isn't able to absorb the energy in
that spike, and/or hasn't reacted to it yet).
Am I following things correctly? I'm not trying to be snotty about
this... I'm going to be building a lot of electronics for the car in the
near future, and it would be nice to know if I need to account for 60V
spike flying around!!
John
'79 300SD
