More 555

goflo at pacbell.net goflo at pacbell.net
Sun Jul 5 23:11:44 GMT 1998


Ron Tyler wrote:
>       Car battery.
> 
>       I have a UEI DMM with freq/duty/PW capability. The last measurment
> I took showed 535hz @ 55%. The circut is built exactly like Bruce B's.
> except that I have substituted a .01 uf for the 470 pf cap.

Have'nt seen the schematic so don't know what it'll do, but
consider that a 4-cycle engine turning 6000 rpm requires an
injector pulse every 20 milliseconds (for sequential injection).

6000rpm / 2 (4-cycle) = 3000 cycles per minute
3000 cpm / 60 sec = 50

In other words the individual injector's pulse rate is 50 Hz
at 6000 rpm. Easy to mix up apples & oranges thinking about 
this stuff.

Jack




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