slim Jim
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| posted on 5/6/07 at 07:10 PM |
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Speedo Sender
The SVA application is in the post and this seems to be my final hurdle (although I am sure another one is just round the corner )
I bought a set of Teleflex gauges from Haneline in good old US of A, as a few others here have done. The speedo sender was no real use for my type 9
box so I have purchased a
reed switch and some magnets.
I have linked up the reed switch up and temporarily attached the magnets to my prop for testing purposes....sadly this does not work.
I have put a multimeter across the switch and the turning the prop the reed switch is activated ok.
The bit I don't understand is if I put my multimeter across the reed switch whilst it is connected to the speedo..... it works (well upto about
25miles an hour anyway)?!?!?!?
Does anyone have any idea what is happening?
Thanks in advance!
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ReMan
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| posted on 5/6/07 at 07:16 PM |
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I would guess that your speedo needs a pulsed voltage to operate it, as found on hall and other proximity sensors, rathere than just a short/open
circuit from a reed switch.
By connecting the meter on Ohms you are supplying a voltage across the speedo and as the switch closes it drops to zero and bingo a nice pulsed
voltage 
So I guess you either got to hide the meter under the dash for SVA or look at getting a different sensor?
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rayward
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| posted on 5/6/07 at 07:22 PM |
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try connecting a resistor (100 ohm) across the reed switch.
may be that the speedo isn;t a high enough load to switch it.
another way to get round it is to connect the supplied sender on the end of the cable which fits the type 9, i have done this temporarliy(on shark
gauges), and it works fine
Ray
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flange nut
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| posted on 5/6/07 at 07:40 PM |
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You need a 12v supply to one side of the switch via a resistor. A 1k ohm one should do the trick. The other side of the switch goes to the chassis.
The input to your speedo goes across the reed switch, making sure its connected the right way round. If you have two wires one will probably be earth
and the other the actual input connection.
+12V
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1k resistor
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|--------------- speedo input
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reed switch
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|---------------- speedo
chassis
Sorry about the drawing
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ReMan
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| posted on 5/6/07 at 07:53 PM |
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quote:
Originally posted by flange nut
You need a 12v supply to one side of the switch via a resistor. A 1k ohm one should do the trick. The other side of the switch goes to the chassis.
The input to your speedo goes across the reed switch, making sure its connected the right way round. If you have two wires one will probably be earth
and the other the actual input connection.
+12V
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1k resistor
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|--------------- speedo input
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reed switch
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|---------------- speedo
chassis
Sorry about the drawing
Nice one, I was'nt thinking simple enough, that should do it
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turbodisplay
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| posted on 6/6/07 at 07:15 AM |
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Reed switches are too slow to operate above 30 mph.
You need a faster hall sensor
Darren
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