 | Home > Td5 > Anybody fitted a rev counter? |
 
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| davew Member Since: 02 Jan 2012 Location: North Yorkshire Posts: 888   
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RS online will have them...
http://www.rs-online.com/index.html The easiest way to build it is to use some Veroboard and build the circuit on that. Was it you that was asking on D44 ? I used that circuit on Pam's TD5 to drive the Compushift tacho, I can't remember the exact values of resistors I used but I can take a look this weekend. http://www.yorkshireoffroadclub.net/ |
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7th Dec 2012 11:43am |
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| Brucey Member Since: 18 Jul 2012 Location: Warsaw, Poland Posts: 61  
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No, not me asking before, it was the thread that prompted the idea!
Any guidance would be great, thanks in advance. So, the ECU pin 19 is the Transistor trigger, switched 12v and ground needed. Transistor ant two resistors...sounds easy enough electrics even for a failed mechanical engineer! 
Chris Defender 110 DC converted Auto BMW R1200GS BMW F650GS Dakar |
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7th Dec 2012 11:48am |
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| davew Member Since: 02 Jan 2012 Location: North Yorkshire Posts: 888
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Had a look at the one I built for Pam's 90, I used 1K ohm resistors for both. http://www.yorkshireoffroadclub.net/
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8th Dec 2012 3:53pm |
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| Brucey Member Since: 18 Jul 2012 Location: Warsaw, Poland Posts: 61
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Great, thanks for taking the trouble Dave. I just need the bits now!
Thanks again. Chris Defender 110 DC converted Auto BMW R1200GS BMW F650GS Dakar |
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11th Dec 2012 10:22am |
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| Perc Member Since: 25 Jan 2013 Location: Westcoast Posts: 18  
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Hello, this is my first post, live in Sweden.
I have tried to connect a tacho as shown by davew but it did'nt work (yet). A friend tested pin 19 with an ocilloscope but culd'nt detect any signal. My 90 is not equipped with either TC or ABS. Could it be so that the ECU needs some programming to deliver a signal on pin 19. Per CSW 90 -03 |
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26th Jan 2013 4:11pm |
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| SteveG Member Since: 29 Nov 2011 Location: Norfolk Posts: 656 
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It shouldn't make a difference, my 90 was base spec too and pin 19 worked.
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26th Jan 2013 9:16pm |
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| Perc Member Since: 25 Jan 2013 Location: Westcoast Posts: 18
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Thanks!
OK, I had to check up so I have a proper contact on the earth side. Did anyone measured the signal with an ocilloscope? Per CSW 90 -03 |
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26th Jan 2013 9:22pm |
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| davew Member Since: 02 Jan 2012 Location: North Yorkshire Posts: 888
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Are you SURE you were using pin 19 ? I ask because the pin layout isn't straight forward and it's very easy to get it the wrong way around. The middle row of pins is numbered the opposite way around to the top and bottom rows so pin 18 and 19 are very easy to get transposed. http://www.yorkshireoffroadclub.net/
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26th Jan 2013 9:35pm |
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| Perc Member Since: 25 Jan 2013 Location: Westcoast Posts: 18
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I think so, I've had checked and doublechecked against the chart over the plint. Tomorrow i will check again from your approach that they are easy to mix up.
Thanks for your support! /Per CSW 90 -03 |
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26th Jan 2013 9:41pm |
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| SteveG Member Since: 29 Nov 2011 Location: Norfolk Posts: 656
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Were you using an analogue scope? I suspect the signal is probably digital. |
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26th Jan 2013 10:11pm |
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| Perc Member Since: 25 Jan 2013 Location: Westcoast Posts: 18
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I don't know, it was a friend of mine who measured, he works with repair of car-audio, and is familiar how to use a scope. He said that he saw mostly "noise".
/Per CSW 90 -03 |
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26th Jan 2013 10:17pm |
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| davew Member Since: 02 Jan 2012 Location: North Yorkshire Posts: 888
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It will be fine digital or analogue scopes will work, not sure if SteveG is pulling your leg or not TBH.
Tell your friend he should see a 5V square wave with 2 pulses per revolution so it's pretty slow by audio standards - at 300RPM you're looking for a 10Hz signal (600 ppm, 10 pps). With the engine not running and the ignition turned on you often see a signal that equates to around 200RPM. As far as I remember the pulses are evenly spaced because the signal is generated by the ECU, it's a fully artificial signal, not directly linked to the engine as such. http://www.yorkshireoffroadclub.net/ |
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26th Jan 2013 10:34pm |
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| Perc Member Since: 25 Jan 2013 Location: Westcoast Posts: 18
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I have checked a little...
Pins: pin 18 - pink, pin 19 the new cabel fitted by me, pin 20 a red cabel, that seems to be correct. I bought a small oscilloscope and tested, last time I used a oscilloscope was 40 years ago, but i think i remember how to use it. I've got the following picture  Click image to enlarge As far as I can read out the signal is about 100 mV and 30 Hz, this is when idling. The curve changes when you throttle. I think that pin 19 is not programmed om my ECU, what do you think? Per CSW 90 -03 |
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29th Jan 2013 3:12pm |
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| davew Member Since: 02 Jan 2012 Location: North Yorkshire Posts: 888
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That looks like noise to me, the signal you are looking for is much bigger and slower than that. You want to be looking at 50ms-100ms on the timeline and 1v per division on the vertical. Make sure the probe is earthed to the same point as the ECU and that the display is visible when you touch the probe to earth.
I've not come across an ECU that doesn't have that output and I've not found any settings that would turn it on/off when playing around with the Autologic diagnostics/programmer. Having said that though, there's always a first time ! If it stops raining this weekend I'll put a scope on mine and get a picture, have to say my scope is a lot more basic than that one though so you have to promise not to laugh ! http://www.yorkshireoffroadclub.net/ |
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29th Jan 2013 3:40pm |
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