theconrodkid
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| posted on 29/4/17 at 12:20 PM |
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complicated lectrical question
My Mazda eunos has an oil pressure gauge but not a light, i would like a light as well.
i plugged an LED into the pressure sensor terminal,turn ignition on.light comes on,gauge stays at zero, start engine,needle goes to it,s normal place
the LED nearly goes out,just a feint glimmer.
so,any way round this,would a resistor put the light out when the engine has pressure or do i have to go about installing a pressure switch.
on the other side of the engine is a plug in a gallery that the turbo boys use to feed their turbo,s, anyone know if this gallery has enough pressure
to operate the switch ?.
TIA peeps 
who cares who wins
pass the pork pies
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peter030371
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| posted on 29/4/17 at 02:30 PM |
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You will need an oil pressure switch 
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02GF74
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| posted on 29/4/17 at 02:39 PM |
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This is not that complicated. But firstly how did you wire the led?
If it is an analogue gauge, dial with needle, then sender is not an open/closed switch. The sender will likely have one end connect to 12 v and other
to gauge input. Connecting any component is likely to affect tbe current/voltage seen by the gauge so will show a different reading compared to
original wiring.
One solution is a comparator circuit that will turn led on or off at a set pressure.
Can you measure voltage at the guage when no pressure and engine running?
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ChrisW
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| posted on 29/4/17 at 03:41 PM |
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quote:
Originally posted by 02GF74
One solution is a comparator circuit that will turn led on or off at a set pressure.
^^ that is indeed the correct way to turn the analogue output from the sender into an on/off output for an LED. It's not mega complicated as
electronics go but not the simplest thing either. It will involve soldering up an integrated circuit (aka microchip).
As has been said, easier to just drill and tap an on/off sender into the block.
Chris
My gaff my rules
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theconrodkid
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| posted on 29/4/17 at 05:16 PM |
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cheers guys
who cares who wins
pass the pork pies
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Smoking Frog
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| posted on 29/4/17 at 07:37 PM |
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I'm sure I fitted a different sender that does both. Direct replacement, cost about £10.00. Will check tomorrow if interested.
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theconrodkid
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| posted on 29/4/17 at 07:55 PM |
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yes please smokin frog
who cares who wins
pass the pork pies
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Schrodinger
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| posted on 29/4/17 at 08:04 PM |
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quote:
Originally posted by Smoking Frog
I'm sure I fitted a different sender that does both. Direct replacement, cost about £10.00. Will check tomorrow if interested.
I used to have one like that on my Tiger, iirc it was supplied by ETB similar to this
http://www.etbinstruments.com/index.php?route=product/product&path=99&product_id=80
or this
http://www.etbinstruments.com/index.php?route=product/product&path=99&product_id=75
Keith
Aviemore
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02GF74
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| posted on 29/4/17 at 08:53 PM |
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Or t-piece like this:
See http://www.vehicle-wiring-products.eu/product.php/218/t-piece-adaptor-1-8-nptf
obviouls depends on thread of the block/senders but there probably be one that suits.
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theconrodkid
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| posted on 30/4/17 at 06:17 AM |
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had a look at T pieces,there isnt a lot of room for one,i lost a pint of blood fiddling down there yesterday 
who cares who wins
pass the pork pies
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Smoking Frog
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| posted on 30/4/17 at 09:56 AM |
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The one fitted to mine is a twin post vdo sender with a thread adaptor. So it's not a direct replacement. Not that cheap now. Quick look on
ebay more like £25.00 + adaptor.
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theconrodkid
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| posted on 30/4/17 at 01:42 PM |
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Ok thanks,i like the dual function idea,ill have a look see if i can get one.
who cares who wins
pass the pork pies
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02GF74
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| posted on 1/5/17 at 06:44 AM |
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25 will buy all the electronic components and lea e change for several pints.
Can you measure resistance across sender when disconnected and voltage at gauge with ign on and engine not running amd running.
A single transistor/resistor/diode circuit coukd work to turn on the led.
Alternately capillary tube to a t piece that is away from the block.
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theconrodkid
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| posted on 1/5/17 at 07:07 AM |
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sorry 02gf75,my limit in electronics is soldering a couple of wires together,ill go for the T piece idea as it is more in line with my abilities 
who cares who wins
pass the pork pies
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theconrodkid
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| posted on 2/5/17 at 11:01 AM |
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found a sender that should fit the bill,the ohms readings go from 10 to 180 according to the seller but my book of words says the sensor on my car
goes from 52 to 160 so......will it work ?
who cares who wins
pass the pork pies
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Smoking Frog
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| posted on 2/5/17 at 01:32 PM |
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This link does suggest "Sender with 0-80 PSI measurement, 5 bar, 10-180 ohms (larger PSI ranges will provide less accurate readings on the Miata
cluster)"
https://sites.google.com/site/redcapsmiata/tutorials/mazda-miata-oil-pressure-sender-upgrade
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Smoking Frog
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| posted on 2/5/17 at 02:33 PM |
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Here's cheap one that seems to fit the bill (that is IF the description is accurate). But it will be on a slow boat from China.
Genuine Oil Press Pressure Gauge Sensor / Type 80psi 10-180 ohm two terminals
Obviously would still need an adaptor.
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theconrodkid
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| posted on 2/5/17 at 03:00 PM |
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^^^ same as i was looking at.
googling seems to say the thread on the original is 1/8 npt,others say bsp....oh well it,s only £8
who cares who wins
pass the pork pies
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Smoking Frog
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| posted on 2/5/17 at 04:26 PM |
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As far as I'm aware 1/8 BSPT. Here's a cheap adaptor, but check if it's the right one as I'm going from memory!
BSP-NPT Adapters , Male BSPT to Female NPT Exten in Brass, European to American
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theconrodkid
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| posted on 2/5/17 at 05:24 PM |
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cheers all,ill get the bits and nail him together now :-)
who cares who wins
pass the pork pies
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