LM1949 drivers/ peak & hold injectors

[john spears]

   If you are applying 15 volts across the injectors and they are only drawing 
 .9 amps, I'd say you have 16 ohm saturated drive injectors, not the peak
and hold style. Peak and hold injectors are generally in the 1 - 2 ohm range.

                  John Spears
    Speartech Fuel Injection Systems


>From: "S. Lastuka" <kicker at u.washington.edu>
>Date: Thu, 6 Mar 1997 18:19:36 -0800 (PST)
>Subject: LM1949 drivers
>
>We are on an SAE team designing an electronic fuel injection system.  We
>have completed the design and have a robust system using a Motorola 68hc11
>MCU to generate the injector pulses.  We are feeding the injector pulses
>into a National Semiconductor LM1949 injector driver.  
>Everything seems to work, ie the injectors click on and off, but on the
>oscilloscope we notice that the injectors are only taking about .9 Amps
>peak and a quarter of that on hold.  We have 2 amp peak, .5 Amp hold
>injectors from Seimans.  
>We then hooked up a 15 volt power supply directly to the injectors to see
>how much current they used with straight uncontrolled power and noticed
>that they still only had .9 Amps across them.  The same results were
>reached with two different injectors.    
>We were wondering if anyone has experience with Seimans injectors in a
>diy efi system and if there is a way to get more current through them, so
>they "peak" faster.  Thank you,
>Sean
>
>ps we're running them dry right now for test purposes, I don't know if
>that makes a difference. 
>
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