ko_racer
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| posted on 19/8/08 at 11:20 PM |
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Electronics Expert Needed
I have two rev counters on my car, both of which run from the ecu tacho wire. One is an elliot rev counter and the other is my aim data logger.
If I wire these up one at a time they both work perfectly.
Once I wire them both up at the same time the elliot one works but the aim mychron one stops working. I'm guessing the elliot rev counter is
cauing the problem here, maybe by dropping the voltage, reducing the signal strength or somthing similar.
Does anyone have any suggestions as to how I can wire up so both of these work at the same time.
Would a diode after I split the wire to the elliot rev counter help here? If so what type do I need to order?
Any help would be great.
Cheers
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stevebubs
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| posted on 19/8/08 at 11:52 PM |
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alternatively run one feed directly from the coil....
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02GF74
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| posted on 20/8/08 at 06:42 AM |
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I suspect you are correct; the loading of the Elliot is too great and distorts the signal enoough for the datalogger to not to make sense of it.
I doubt a diode would make any difference.
The Elliot has a "charge pump" so will draw a more current than your digital data logger - usaully they are connected to the coil - and
you are probably lucky that it was working off the ecu.
So what do you do?
Either connect Elliot to coil - as suggested - and ho I have mine connected - or you need to have a buffer that can switch more current.
I would suggest the former as it is just a piece of wire.
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ko_racer
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| posted on 20/8/08 at 07:56 AM |
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Problem is the 06 R1 I have is coil on plug so I can't use the unductive pickup. Would the elliot rev counter work from the negative pulse line
from the coil pack?
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mackei23b
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| posted on 20/8/08 at 08:51 AM |
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quote:
I'm guessing the elliot rev counter is cauing the problem here, maybe by dropping the voltage, reducing the signal strength or
somthing similar.
quote:
A buffer amp would resolve this issue, if this was the case.
Cheers
Ian
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ko_racer
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| posted on 20/8/08 at 09:29 AM |
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Cheers,
Have got any suggestions as to how I design the buffer amp, I've a bit of electronics background but not much. I would guess I need a
transistor circuit, but wouldn't have a clue how to select the correct type and specify any other supporting resistors etc. Do they cope with
the type of switching frequencies needed easily and would there be much of signal delay?
In my head I see it working like a realy but switching at a very high speed with two independant outputs.
Cheers
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BenB
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| posted on 20/8/08 at 10:26 AM |
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a cheapo op-amp in buffer mode would suffice. You'll likely need a rail-to-rail op-amp because the signal may well be at the same voltage as the
op-amp supply, and unless you want to create a virtual earth you'd need an op-amp able to run off a single supply.
personally I'd try the diodes first....
you could connect it to the supply to the pulse line to the coil pack but it would be getting less signals so you'ld need to adjust for the
number of cylinders...
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BenB
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| posted on 20/8/08 at 10:40 AM |
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instruct1.cit.cornell.edu/courses/bionb440/datasheets/SingleSupply.pdf
and
http://focus.tij.co.jp/jp/lit/an/sboa059/sboa059.pdf
might point you in the right direction...
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ko_racer
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| posted on 20/8/08 at 11:01 AM |
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Thanks, I'll have a read.
Cheers
Keith
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