Repost

[Tony Bryant]

I've just realized after sending my last post 
re. Holding injector at an average 300mA for cleaning
purposes
- that my logic was somewhat flawed.

You probably cannot hold a particular current through
the injector by simply setting a fixed duty cycle
since either:

1) if your duty cycle is below the critical value,
your average current will fall.

2) if your duty cycle is above the critical value,
your average current will rise.

So, infact you need a feedback from the average current
to control the duty cycle. 

IIRC the LM1949 can operate in this very mode. 

Hmmm - what about an in-car auto-clean mode, that operates
the LM1949 in switching mode, modulating the required
current through a sequence of say .4A down to .1A over
a space of a second (with the fuel pump running)?


'71 510 Daily driver
'72 510 Race car
'85 V12 XJ-S Garage ornament