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Please view this spice file.. (fuel injector driver amp)


John S

Jan 1, 1970
I did up a driver amp for an injector and first I need some opinions
if the think the valve is going to drop out between pulses. I am at home
at the moment and did not bring with me any injectors to work with.

The valve will not drop out between pulses.


Jan 1, 1970
John said:
The valve will not drop out between pulses.
And I don't want it to. When it's done with that cycle, I'll simply
turn it off.

The idea is to snap it on hard with a longer pulse and then
shorten the duty cycle to ease back on the current.

I came up with the driver amp that will return the energy to the
power supply. I now simply need to create a pulse timer that has a
long pulse width on first initial start and then start pulsing with
a shorter duty cycles. When that request is done from the external
trigger source, it will simply turn off the clock source I have for the
pulse train.

It's as simple as that.

We will most likely be using a throttle body type TBI and they require
a lot of current on the initial pull and then it needs to be eased back
to not burn out the coil. This is where the PWM duty variation comes
into play.

I will need to also have a one-shot timer to adjust the over all
demand on each cycle.

I suppose one could do this with a dual 555 timer. One as the
One-shot the other has the PWM signal.

There is a way to set up a 555 timer to have a longer starting pulse,
that maybe the easiest thing to do for this.

I was also thinking about using a LM324 type chip and current sense
to create a hysteristic pulse where I can simply vary the current as the
portion control on the holding current.


Fred Abse

Jan 1, 1970
What is that suppose to me ? :)

Please fill me in! I am all ears!

Xylene softens and even dissolves some plastics. Similar to benzene.

Automotive injectors can incorporate plastics, make sure they're
compatible with xylene.

"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)