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Author: Subject: Three wire speed sensor
Abe

posted on 26/7/19 at 06:08 PM Reply With Quote
Three wire speed sensor

Hi gang

Ok Iíve done something stupid... bought, made bracket, fitted magnets to drive shaft and installed a three wire speed sensor from Tiger racing... looks lovely... except my ETB electronic speedo is an older two sensor wire input. Obviously Iím not getting a reading. Am I right in thinking I need to replace the sensor with a two wire or can a three wire one be made to work? Three wire is negative positive and signal DC I believe whereas the two wire I believe is AC. Hope that makes sense!

[Edited on 26/7/19 by Abe]

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gremlin1234

posted on 26/7/19 at 06:16 PM Reply With Quote
quote:
Originally posted by Abe
Hi gang

Ok Iíve done something stupid... bought, made bracket, fitted magnets to drive shaft and installed a three wire speed sensor from Tiger racing... looks lovely... except my ETB electronic speedo is an older two sensor wire input. Obviously Iím not getting a reading. Am I right in thinking I need to replace the sensor with a two wire or can a three wire one be made to work? Three wire is negative positive and signal DC I believe whereas the two wire I believe is AC. Hope that makes sense!

[Edited on 26/7/19 by Abe]

you might be able to make it work with various pull up/down resistors,
but some sensors pull down, other up, so quite likely not.

just get the right sensor, else you will always be doubting it.

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Abe

posted on 26/7/19 at 06:51 PM Reply With Quote
I donít know what pull up/down resistors are, so probably best I just get the correct sensor

Thanks for your reply

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02GF74

posted on 26/7/19 at 07:16 PM Reply With Quote
Etb wiring diagrams here
https://www.etbinstruments.com/index.php?route=product/category&path=17_85

Which model is yours.

A 2 wire speedo either will accept a pulse signal or have the wires grounded. If you are feeling brave, then connect to the speedo 2 wires, then rapidly touch them together, if the pointer moves then we know how to drive it.

A metal comb is ideal for this test by dragging wire across the prongs will give rapid pulses.

Tbh sounds like electrickery is a mystery for you, how much is the correct sensor as you may damage a very expensive speedo.





Visit China. Meet the child that made your trainers.


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Abe

posted on 26/7/19 at 07:50 PM Reply With Quote
Hi bud

Thanks for the reply....Itís not a Ďcompleteí mystery as Iíve built a few wiring looms in my time, but I do have some gaps with stuff like this
Itís this speedometer... 80mm ETB Electronic Speedometer Mk2 (Rubber button on glass).

The original sensor was a two wire, picking up off a 15 hole disc off the prop shaft, smashed and mounted horribly, a new one is £80, the one I bought from Tiger that I thought was compatible although mounted in a different location is £32. Was trying to save a few quid and make a tidy job of mounting it too. Someone had already mounted a magnetic pick up, but that had been disconnected and was hanging off.

[Edited on 26/7/19 by Abe]

[Edited on 26/7/19 by Abe]

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02GF74

posted on 26/7/19 at 09:03 PM Reply With Quote
below is the relevant section; note the reed switch option.

either fit a reed switch - not ideal as they have limited lifetime and prone to bounce at high rpm - better make use of your 3 wire sender to drive a transistor switch; example circuit using FET shown.




FET as a switch






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Abe

posted on 26/7/19 at 09:36 PM Reply With Quote
Thank you so much thatís massively helpful
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ianhurley20

posted on 4/8/19 at 10:07 PM Reply With Quote
I would be very interested in knowing if you got your speedo sorted - we have exactly the same non working set up at the moment!





My build blog http://ianhaynes20.wordpress.com IVA passed 3/10/16
written off 23/9/18
Aug 2019 completed Tiger Avon with ST170 on TB's
Now restoring 1968 Ginetta G4
And - a series 1 Land Rover - don't ask why!

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Abe

posted on 4/8/19 at 10:39 PM Reply With Quote
Hi bud

I bought a cheap threaded M8 Reed sensor from eBay and have mounted that. After some speedo calibration i got some accurate results against my GPS. That is until after 5 minutes, then the needle starts getting erratic and not at particularly high revs either. I may get a new speedo and use my three wire hall speed sensor as the lcd display on my speedometer has also started glitching. Will play about tomorrow if I get time.

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ianhurley20

posted on 5/8/19 at 07:50 AM Reply With Quote
Thanks for the update, our 3 wire sensor (Burton Power) will not light up the speedo at all at the moment, I'll post a solution if I find one.

[Edited on 5/8/19 by ianhurley20]





My build blog http://ianhaynes20.wordpress.com IVA passed 3/10/16
written off 23/9/18
Aug 2019 completed Tiger Avon with ST170 on TB's
Now restoring 1968 Ginetta G4
And - a series 1 Land Rover - don't ask why!

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