Briggs-sized injectors, drivers, and pleasant development environments

[Matthew Lee Franklin]

An injector that may work well for a Briggs application is a BOSCH 
280 150 210.   The parts guy at the BMW motorcycle dealer said is is used 
in a 1985 and newer K75 with the 750cc three cylinder.  I have succesfully 
used one in a small Briggs-based research setup.  Another student here is 
currently using one on a 350cc Onan generator for a research project.  I 
think list on it was about $130.24.  Its internal resistance is about 
16.3ohms, so I think it is meant to be driven with a saturation driver.  

However, I use a Motorola MC3484-S4 driver since that's what I had on 
hand, it works just like a saturation driver at 12V and 16.3 ohms, and it 
is a nice, integrated package.  ALSO, I tend to let the magic smoke out of 
most of the lone transistors I touch, so in the long run the integrated 
driver chip saves me money.  They cost about $4.50 each from Hamilton-
Avnet, but you have to buy at least 40 or 50 at a time.

I'm using one of the most pleasant environments for developing and 
debugging engine management systems.  It started with a prototype card 
stuffed with six Intel 8254 programable counter timer chips and some 
supporting logic.  The card is plugged into an 486-25 IBM compatable PC and 
is programmed in QuickBASIC in the pseudo-interpreted mode.  The system 
has been used for the last couple of years to study optimization strategies 
for air-fuel ratio and ignition timing on port fuel injected natural gas 
engines in our dyno lab.  I know many will be disappointed that the system 
is not done with a lone 68-something processor or microcontroller and 
programmed assembly language or C, but I'm only an ME with just enough EE 
in me to be dangerous.  Besides, the system really shortens the development 
cycle, and if you ever have to explain a program to anyone else, BASIC is 
the one common language that all can understand.

Later,
Matt

Matthew L. Franklin     
University of Minnesota     
Department of Mechanical Engineering
111 Church Street Southeast
Minneapolis, MN 55455-0150
Phone: (612)625-4074                       
FAX:   (612)624-1398
Home Phone/FAX: (612)331-3511