[V8] more speedo drivel

[dsaad at icehouse.net]

Good points Steve. I went with the lower value mostly because that was what I 
had in my hand - but I also figured the sender would either take it or die 
trying. I fully expect to be ordering a new sender in the near future. I have 
proved in my mind anyway that the old one is not reliable anymore.

Your second point is hard to investigate. Everything always works when the car 
is sitting in the garage and it is near impossible to monitor this voltage at 
the sender while driving. I am leaning away from the power supply wires having 
high impeadance mostly because I can see that the sender does not work as 
expected on a bench supply.

Dave

btw, anybody out there in V8 land have a used 5-speed sender they want to part 
with?

(I didn't think so... :-)



Quoting "Buchholz, Steven" <Steven.Buchholz at kla-tencor.com>:

> ... interesting data point David!  I do have a "bad" distributor on the
> bench in the garage ... when I get a chance I'll try your trick.  
> 
> The one thing I did want to comment on is the use of a 400 ohm resistor.
> 30mA in addition to whatever load is already placed on the signal at the
> other end of the wire might tend to overstress things a bit.  If you can
> make things work with a 1K resistor, all the better.  In fact, I'd
> recommend
> something even higher ... say 4.7K.  This will minimize the amount of
> current that the Hall Sender is being asked to source ...
> 
> The other thing that would be interesting would be to check the voltage
> supply to the Hall Sender both when it is loaded (connected to the
> sender)
> as well as open.  If you see 12 volts open circuit that drops to
> something
> like 9v with the load of the sensor applied that would be telling as
> well.
> Either the source has a problem with a high impedance, or the sensor
> itself
> is drawing too much power ... 
> 
> Steve B
> San Jose, Kaleefohnia (USA)
> > 
> > For anyone who wants to try this on their intermittent speedo 
> > or distributor 
> > sender, I tried both a 1K and a 400 ohm resistor. Both 
> > worked. I went with the 
> > 400 ohm 1 watt for a little extra drive current (around 30mA).
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