Simple injector Drive

[Ed Lansinger]

Bruce Bowling wanted to know:

>The injectors are the 16 ohm variety (GM).
>What is the simplest circuit (FET, etc) that will take
>the TTL and open the injector safely for a short test
>and clean time.

Others have suggested good drive circuits.  Personally, I go to Radio Shack
and get a TIP120 power darlington and a 4.7K ohm resistor.  Run the TTL
output into the resistor and then into the base of the TIP120.  Emitter of
the TIP120 should be grounded and the collector goes to the injector (with
12 volts on the far side of the injector).  There is no need for a flyback
diode or other protection as the TIP120 can handle repeated inductive kicks
of up to 60mJ due to internal protection.  I don't recall needing a heat
sink even when running for extended periods of time at 50% duty cycle.

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Ed Lansinger
General Motors Powertrain
Powertrain Control Center
Premium V Software & Calibration Group
Milford Proving Ground, Milford, MI
elansi01 at mpg.gmpt.gmeds.com  8-341-3049  (810) 684-3049
The waffles stated above are mine, not my employer's.
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