[DML] Re: RPM Relay - A Modern Alternative

["David Teitelbaum" <jtrealty@xxxxxxxxxxxxx>]

I would suggest you test all possible failure modes. This is a key
safety item and it MUST "fail safe". I applaude your efforts to
improve the Delorean but you may be allowing yourself too much
potential liability exposure. The current RPM relay available from the
vendors has a low failure rate and it only seems to "fail safe". I
have never heard of an instance of a properly wired car where the RPM
relay failed in a constant run state. Even if you are not planning on
making any money on this you certainly don't want to lose money
either! Just defending yourself in a lawsuit can be costly even if you
win! Maybe a double-redundant circuit could make it less likely to
fail "ON". A relay (mechanical) element has certain inherent safety
advantages. That's why it has to be constantly energized, it opens the
circuit if loses signal (fail safe). A shorted power transistor can
make the pump run constantly (even if the motor should stop with the
key on). Just substituting a power transistor will reduce the power
requirements but that's not all that the relay does!
David Teitelbaum
vin 10757


--- In dmcnews@xxxxxxxxxxxxxxx, "tho323" <tho323@...> wrote:
>
> I have been beta testing a new, re-engineered RPM Relay design, and
> wanted to share my thoughts about it. I have posted a full review at my
> blog (link below), and here are some key excerpts:
> 
> 
[moderator snip]

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