Rev counter powered from hall type sensor?

[Bugsy_malone 666]

I presume that an ABS sensor is a hall sensor?

Basically I have some hubs for a mk3 golf GTi with ABS sensors on them, when I fit the hubs to my mk3 I wont need the ABS sensors but I think I remember reading somewhere about using ABS sensors to use as a trigger for rev counters?

I have a Baywindow Camper van with a golf 1600TD in and want to fit a rev counter too it so thought maybe as I have the bits kicking about maybe now would be a good time to test this project out.

So will the ABS sensor work? If so are there any modifications I need to make to the rev counter and whats the best way to wire it?

With regards to getting a pulse whats best here? do I just need a raised spot that runs approx 1mm from the sensor head for a short burst?

Eventually I have been thinking about using the second ABS sensor on one of the wheel hubs somehow to use to give me a speed reading and I want to tie a number of different sensors together and an Arduino microcontroller together to dislplay all my vitals on one digital display, maybe even my MPG read out if I can find the right sensors!

[bajacalal]

I think it would be much easier to use the alternator (the 'W' terminal) as a tachometer drive like VW did with some of their models which came with a tach. You can find a tachometer like this on ebay. It may be one intended for a boat but it will work if can be hooked up the alternator W terminal (AC output that varies in frequency). Get one that can be adjusted so you can calibrate it.

[745 turbogreasel]

I presume that an ABS sensor is a hall sensor?

No, hall sensors have blades in a gap, not that there is anything wrong with the traditional magnetic trigger.
Also, W terminal  is way easier, and you can add one to your alternator if you have a soldering iron(it taps on to any one of 3 stator windings.)

[R.O.R-2.0]

i was just thinking of using a hall sender for a tach drive the other day 

[Bugsy_malone 666]

I presume that an ABS sensor is a hall sensor?

No, hall sensors have blades in a gap, not that there is anything wrong with the traditional magnetic trigger.
Also, W terminal  is way easier, and you can add one to your alternator if you have a soldering iron(it taps on to any one of 3 stator windings.)

But an abs sensor has lots of gaps/blades? Or is that what you mean? I just have some abs sensors and wonder how they worked exactly because I want to make one be the pickup for my revcounter and maybe another as a speedo pickup (I want to build a custom digital display.) I figured because of their purpose I maybe able to utilise them.

The reason for not using the 'w' terminal is the fact I dont have one, I dont really want to take my alternator to bits to fit one if I can help it! Basically because this would be in my camper, theres no standard rev counter that goes in, instead I was considering getting something like an Autometer Gauge (something big and fun looking) which alot of people fit to the normal aircooled campers (its just I chose to stick a diesel in mine!).

[bajacalal]

If it's a Golf diesel, unless it's a really early model, it should still have the W terminal, even if the donor car did not have a factory rev-counter it should still have the W terminal assuming the alternator is the original unit, because the W terminal was used for other functions as well. I have seen them on gasoline... umm, petrol engines, maybe not the original alt. but still, there it was.

Your idea WILL work, I'm not trying to say it won't, my diesel pickup truck has this kind of sensor for the RPM, what I am saying is that this is not the path of least resistance, it will require engineering... The path of least resistance is using the W terminal because you only need 3 things- an alternator with the W terminal, some wire, the right tachometer/rev counter. It's easy.

You don't need to use an original VW instrument cluster either, you can have a big tachometer on your dashboard like you want, as long as it can use the waveform signal from your alternator and is adjustable. I have one out of a boat. It says "BMW Marine" on it and is 3.5" diameter. Most aftermarket gauges meant for a spark-ignition won't work, I've tried, but the right unit isn't too hard to find.

[R.O.R-2.0]

I presume that an ABS sensor is a hall sensor?

No, hall sensors have blades in a gap, not that there is anything wrong with the traditional magnetic trigger.
Also, W terminal  is way easier, and you can add one to your alternator if you have a soldering iron(it taps on to any one of 3 stator windings.)

But an abs sensor has lots of gaps/blades? Or is that what you mean? I just have some abs sensors and wonder how they worked exactly because I want to make one be the pickup for my revcounter and maybe another as a speedo pickup (I want to build a custom digital display.) I figured because of their purpose I maybe able to utilise them.

The reason for not using the 'w' terminal is the fact I dont have one, I dont really want to take my alternator to bits to fit one if I can help it! Basically because this would be in my camper, theres no standard rev counter that goes in, instead I was considering getting something like an Autometer Gauge (something big and fun looking) which alot of people fit to the normal aircooled campers (its just I chose to stick a diesel in mine!).

solder on a W terminal, and buy a used boat/tractor tach off ebay

its really not as hard as you think to solder on a W terminal..

[Bugsy_malone 666]

Well I know my alternator doesnt have a w terminal on it, its not a bosch one but a lucas unit thats been remanufactured (65amp) Typically I had a decent 90amp one off a newish caddy that had the W terminal, but due to a winter of it being under a tarpaulin the things siezed up! (yet the alternator off something else I have on the bench has been outside for 3 years there and still turns fine!)

does anyone have a link to a guide of fitting the w terminal to non w alternators?

Aside from that relating to my original question, how does the ABS sensor actually work? I need to rig one up for speed sensing.

[R.O.R-2.0]

Well I know my alternator doesnt have a w terminal on it, its not a bosch one but a lucas unit thats been remanufactured (65amp) Typically I had a decent 90amp one off a newish caddy that had the W terminal, but due to a winter of it being under a tarpaulin the things siezed up! (yet the alternator off something else I have on the bench has been outside for 3 years there and still turns fine!)

does anyone have a link to a guide of fitting the w terminal to non w alternators?

Aside from that relating to my original question, how does the ABS sensor actually work? I need to rig one up for speed sensing.

its just a magnetic pickup.. reads the slots in the reluctor ring..

[regcheeseman]

Why bother when there is a sensor fitted to the pump that gives 2 pulses per rev - exactly what a revcounter would expect to see.

Well fitted to most pumps anyway....a pressure switch sat in the centre of the pump head with a NO output.

As soon as I've a running motor I'll make up a cable to do the signal conditioning, but putting a meter on at idle records around 32 HZ at idle which is 960 rpm.

[R.O.R-2.0]

Why bother when there is a sensor fitted to the pump that gives 2 pulses per rev - exactly what a revcounter would expect to see.

Well fitted to most pumps anyway....a pressure switch sat in the centre of the pump head with a NO output.

As soon as I've a running motor I'll make up a cable to do the signal conditioning, but putting a meter on at idle records around 32 HZ at idle which is 960 rpm.

most of us on this side of the planet never got that sensor..