What about MOV's? Typical
transient response time measured in nanoseconds...
<Marv>
My expert, who has
designed ECUs for other applications, had the following comments that may be
of interest:
As far as the ECU goes, the
diodes should be replaced with
tranzorbs or zeners of about 30
volts. I don't think a pull down resistor
of 1K as suggested will do
anything at all. It should be roughly 8 times
the injector resistance
(assuming the injector hold current is less than 8
times the pull-in current --
typically it's between 4 and 6). And if you
want a true peak and hold
injector driver, then the National LM1949 is the
way to go.
The resistor only makes
sense at very high RPMs,
probably higher than what the engine can do, so I
consider it optional. The
relay contacts are not the issue. The issue is
protecting the drive transistor
which will fail at voltages lower than what
will cause an arc in the relay
(not to mention RF noise). The other issue
is minimizing the current flow
as the magnetic field collapses.
As previously mentioned, the
‘correct’ way to drive a high flow rate injector is using a
peak and hold
circuit.
FWIW;
Al
G