Avoid the expense?
08 January 2007, 11:02 AM
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Avoid the expense?
anyone paid 109 quid plus vat for a crank position sensor? Well at work recently i was looking for something in the RS catolouge....I found this sensor which looks like it may do the job.....Hall effect sensor (used for detecting the position of rotating metal bodies). RS part number 235-5706. The sensor looks very similar and the purpose is spot on.....Problem theres no plug socket so it would involve termination.....Anyone care to test the theory...Im gonna buy one just to test it.....Ill let you know....maybe another after market part for the classic owners.
Oh and its around 20 quid
Oh and its around 20 quid
08 January 2007, 02:16 PM
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I was under the impression that the crank sensor on all Imprezas is a inductive trigger (2 wire), well on the classic shape models anyway. A typical Hall effect sensor requires a regulated power supply and is thus 3 wires.
Not knowing which, if any model years used 3 wire sensors, I can't comment on suitability.
But for models with the two wire inductive trigger type sensor, you need to ensure that the voltage values at a given rpm are the similar. The main requirement will be a minimum of 0.4volts peak to peak on an oscilloscope at cranking speed.
Typically the peak to peak voltages of this type of sensor should give is roughly 5volts at 1000rpm and about 100volts at 6000rpm and when observed on a osilloscope is roughly that of a sine wave.
A typical Hall effect sensor switches between the supply and ground, giving a sqaure wave on a scope at a fixed voltage, regardless of engine speed. So the two types would not be directly interchangable.
Not knowing which, if any model years used 3 wire sensors, I can't comment on suitability.
But for models with the two wire inductive trigger type sensor, you need to ensure that the voltage values at a given rpm are the similar. The main requirement will be a minimum of 0.4volts peak to peak on an oscilloscope at cranking speed.
Typically the peak to peak voltages of this type of sensor should give is roughly 5volts at 1000rpm and about 100volts at 6000rpm and when observed on a osilloscope is roughly that of a sine wave.
A typical Hall effect sensor switches between the supply and ground, giving a sqaure wave on a scope at a fixed voltage, regardless of engine speed. So the two types would not be directly interchangable.
Last edited by Shark Man; 08 January 2007 at 02:20 PM.
08 January 2007, 02:34 PM
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RS also sell 2 wire inductive sensors too 
Can't say if they will work, but you need one that can switch as fast enough and provide the voltage.
The crank sprocket on models fitted with the 2 wire inductive sensors has 6 lobes, so you need a sensor that can cope with at least 7000rpm x 6 which equates roughtly to 120Hz x 6 = 720Hz and be sensitive enough to give at least 0.4 volts peak to peak during cranking and not provide too much voltage at high rpm as to blow the ECU (that maximum limit I do not know ).
Can't say if they will work, but you need one that can switch as fast enough and provide the voltage.
The crank sprocket on models fitted with the 2 wire inductive sensors has 6 lobes, so you need a sensor that can cope with at least 7000rpm x 6 which equates roughtly to 120Hz x 6 = 720Hz and be sensitive enough to give at least 0.4 volts peak to peak during cranking and not provide too much voltage at high rpm as to blow the ECU (that maximum limit I do not know ).
08 January 2007, 02:37 PM
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In my experience it doesnt matter whether its an inductive sensor or a hall effect sensor...hall effect and inductive can both be used to measure proximity.....the hall effect however would use a transistor to create a digital output...the hall effect is widely used to measure the thickness of materials by its relationship to a steel ball bearing placed on the other side of a material. likewise its possible to get an analouge output from an inductive transducer via current.
I never had the crank out of a scoob but surely its got a lobe thats higher than the rest of the material.....this no matter digital or analouge would create a pulse to say there is movement?
I never had the crank out of a scoob but surely its got a lobe thats higher than the rest of the material.....this no matter digital or analouge would create a pulse to say there is movement?
Last edited by thedeester1; 08 January 2007 at 02:41 PM.
08 January 2007, 02:43 PM
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I was under the impression that the crank sensor on all Imprezas is a inductive trigger (2 wire), well on the classic shape models anyway. A typical Hall effect sensor requires a regulated power supply and is thus 3 wires.
Not knowing which, if any model years used 3 wire sensors, I can't comment on suitability.
But for models with the two wire inductive trigger type sensor, you need to ensure that the voltage values at a given rpm are the similar. The main requirement will be a minimum of 0.4volts peak to peak on an oscilloscope at cranking speed.
Typically the peak to peak voltages of this type of sensor should give is roughly 5volts at 1000rpm and about 100volts at 6000rpm and when observed on a osilloscope is roughly that of a sine wave.
A typical Hall effect sensor switches between the supply and ground, giving a sqaure wave on a scope at a fixed voltage, regardless of engine speed. So the two types would not be directly interchangable.
Not knowing which, if any model years used 3 wire sensors, I can't comment on suitability.
But for models with the two wire inductive trigger type sensor, you need to ensure that the voltage values at a given rpm are the similar. The main requirement will be a minimum of 0.4volts peak to peak on an oscilloscope at cranking speed.
Typically the peak to peak voltages of this type of sensor should give is roughly 5volts at 1000rpm and about 100volts at 6000rpm and when observed on a osilloscope is roughly that of a sine wave.
A typical Hall effect sensor switches between the supply and ground, giving a sqaure wave on a scope at a fixed voltage, regardless of engine speed. So the two types would not be directly interchangable.
Think i best get back to Scooby General, at least i can almost follow the "innit, dump valve" conversations.
08 January 2007, 02:49 PM
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strangely enough just cause there are only 2 wires means nothing.....most DC supplies have 3 wires....some sensors however....especially on motor vechicles have 2 and take there 0v from an in built conductive body....since all metal on a car is connected to the -ve terminal of a battery then thats as cood as your gonna get.
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08 January 2007, 02:54 PM
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Point taken.
Easy way to test what sensor you have...disconnect it and connect it to an ocsilloscope and crank the engine, a (good) inductive sesnor will give a a/c voltage signal. As that does not require any power to drive the sensor.
Easy way to test what sensor you have...disconnect it and connect it to an ocsilloscope and crank the engine, a (good) inductive sesnor will give a a/c voltage signal. As that does not require any power to drive the sensor.
08 January 2007, 02:59 PM
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you still have to power an inductive sytem!!!!!otherwise its some wire with an oscilloscope attached...the inductive transducers work by reading a field...not by been enduced by a dead entity....jesus if i could do that id be worth trillions.....LOL
08 January 2007, 03:05 PM
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It doesn't have to have power. Its the same undelying principals as the inductive pickup on a magneto ignition system.
I'm just wasting my time here. Sort it yourself, bye
I'm just wasting my time here. Sort it yourself, bye
Last edited by Shark Man; 08 January 2007 at 03:08 PM.
08 January 2007, 03:14 PM
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your talking about inducing a DC voltage...which is impossible....you can induce a sine wave but thats not gonna work a sensor. I made a generator as an apprentice once and the best i managed to get to dc was 40hz. right hand law, left hand law........drive or be driven......yes or no is not an option....analouge verses digital
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