Colin Burchall wrote:
>
>
> With regards to back-EMFs from relay coils, there have been many
> accidental omissions of the diode by manufacturers over the years. In
> some cases this can fry very expensive ECUs under normal operating
> conditions, and has been the topic of several service bulletins.
>
The service techs at work came to me because they were losing a lot of
control boards on a gas turbine. When I investigated, I found that over
the years some of the diodes across relays had failed. The service
techs, just cut out the shorted diodes and didn't replace them. I had
them go through and replace all the missing diodes and explained the
purpose of them. That cured the rash of failed control boards.
Another thing that happens when you put a diode across the relay, is the
relay hangs in a little longer than it would if the diode wasn't there.
This is because when the magnetic field collapses current flows and and
the resulting magnetic field holds the relay closed for a short time.
--
Jim Coon
Not just another pretty mandolin picker
mailto:[EMAIL PROTECTED]
If Gibson made cars, would they sound so sweet?
My first web page
http://www.tir.com/~liteways/
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