Agriv8
|
| posted on 4/4/08 at 10:37 AM |
|
|
VDO Spedo and Sender problem
My spedo has never liked reading above 80 mph ( on the track of course  ) and also had no problems passing SVA.
But when I got passed 80 the spedo would sudenly reads 1/2 the road speed This issue has finally got to the top of the list of things to sort.
I had 2 magnets on the Prop so I though increase this to 4 and it may solve the issue BUt alas No the spedo now only read to 30 mph ( estimated ) I
have tried moving the sensor to 1mm and out as far as 3mm ( from the magnets. I have checked the setup and wiring to the guides on the ETB instruments
site .
But I am unsure if I have a Hall affect Sensor or an Induction Sender ( anyone know how to tell the diference and if this could be the issue would
magnets not work with either of them ?)
So over to you chaps for some further ideas.
Thanks in Advance
Agriv8
Taller than your average Guy !
Management is like a tree of monkeys. - Those at the top look down and see a tree full of smiling faces. BUT Those at the bottom look up and see a
tree full of a*seholes .............
|
|
|
|
|
stevec
|
| posted on 4/4/08 at 10:50 AM |
|
|
Inductive sensors usually have 2 wires, Hall effect have 3,
Steve.
|
|
|
coozer
|
| posted on 4/4/08 at 10:57 AM |
|
|
How do wire a hall affect sensor where theres been an Inductive one please??
1972 V8 Jago
1980 Z750
|
|
|
02GF74
|
| posted on 4/4/08 at 11:01 AM |
|
|
Do you have manual for this speedo?
What info. do you have about the sensor input to the speedo?
Obvioulsy all electronic speedo as programmable for number of pulses per mile or similar to allow for different sized wheels, diff ratios and number
of magnets so you are setting this correctly?
Does the speedo read correctly but goes bonkers at 80 mph and above?
One of two possible things:
the speedo is not able to handle the pulses coming at it at high speed or the pulses are not right.
I would start off by testing the speedo itself by spinning a disc with magnet or similar fitted to a drill to provide pulses and see if speedo does
read correctly.
if yes, then investigate the sensor.
|
|
|
02GF74
|
| posted on 4/4/08 at 11:02 AM |
|
|
quote:
Originally posted by stevec
Inductive sensors usually have 2 wires, Hall effect have 3,
Steve.
makes sense: positive power suply, negatvie power supply and sender output.
|
|
|
stevec
|
| posted on 4/4/08 at 11:15 AM |
|
|
quote:
Originally posted by 02GF74
quote:
Originally posted by stevec
Inductive sensors usually have 2 wires, Hall effect have 3,
Steve.
makes sense: positive power suply, negatvie power supply and sender output.
Yep thats how I see it,
You get a square wave signal from a hall effect and a AC wave from an inductive.
Steve.
|
|
|
02GF74
|
| posted on 4/4/08 at 01:12 PM |
|
|
quote:
Originally posted by stevec
quote:
Originally posted by 02GF74
quote:
Originally posted by stevec
Inductive sensors usually have 2 wires, Hall effect have 3,
Steve.
makes sense: positive power suply, negatvie power supply and sender output.
Yep thats how I see it,
You get a square wave signal from a hall effect and a AC wave from an inductive.
Steve.
agree again, but the Hall would also give a non square wave, if it were not for the electronics magic inside that sends output to either max or min
if the hall signal goes above/below a certain threshold.
|
|
|
Macbeast
|
| posted on 5/4/08 at 07:47 PM |
|
|
Maybe if the speedo can't cope with the high pulse rate, the answer might be to run with only one magnet, not double them ?
|
|
|
02GF74
|
| posted on 6/4/08 at 09:18 PM |
|
|
there is another popssibilty and that is reed swtich in sensor.
these contain a small strip of metal that is attracted and bends to complete a cirtcuit when close to a magnetic - the repsonse time of these is very
much greater than the other types so one would expect these to not workat high frequencies.
if you hold one of these to your ear and bring a magnet close by, you shold be ableto hear a tiny click.
|
|
|
