14 replies to this topic

[jamiestevenbell]

hi guys just a quick question with regards to wiring a smiths temp gauge the problem i have is theres no markings on the back to say what wire to connect where. there is two terminals on the back the way i look at it is onse from the sensor and ones a live? any help is much appreciated the gauge i have is like this http://www.ebay.co.u...=item4cf65d46fd

[WiredbyWilson]

any chance of a photo of the back of it?

[jamiestevenbell]

http://www.google.co...iw=1280&bih=605
looks just like this

[Dan]

Doesn't matter which is which, all it's running inside is a heater. One connects to the sender, the other connects to a regulated 10v supply from a Smiths voltage stabiliser or other regulated source. If you give it a plain supply off the ignition it will read all over the place.

[lrostoke]

Easiest way find out is connect on terminal to a 12v positive and touch the other terminal to a good earth, watch which way the needle goes.
If it goes up its correct.

Once you find the positive wire connect that to the voltage regulator.

The other connects to the sensor.

I know some guages it doesn't actually matter which is which, they work both ways.

Edited by lrostoke, 19 March 2012 - 10:34 AM.

[jamiestevenbell]

where would i buy a voltage regulator from?

[lrostoke]

If you have the center binacle clocks its normally attached to the back of the speedo

[Dan]

Almost any auto electrical place, any Mini or other classic car dealer, kit car parts dealers, race and rally preparation companies, ebay, autojumble, all over really. They aren't remotely uncommon, but they are increasingly expensive as newer gauges don't need them. It's cheaper by far to make your own from a commonly available chip that regulates a 10v output. There is advice here about how to make one if you search. What gauges do you have currently? The standard ones all have a regulator in of one kind or another and one reg can run two gauges (or is it 3?).

[jamiestevenbell]

i have a centre clock speedo i think i know which bit you mean so i would take my live off of the bak of the voltage regulator?

[Dan]

It has a terminal marked I for instrument. This will be where it is connected to the fuel gauge, not sure from memory how easy it is to break in there but you need to get power from that connection.

[jamiestevenbell]

ok cheers

[dklawson]

Boy... I missed the whole thread. Follow Dan's advice and your gauge will work fine. If it is too hard to tap into the "I" output of the existing voltage stabilizer, look for a 7810 chip from an electronics supply house. That is a 10V solid state voltage regulator for negative earth. The picture linked below is from my friend Wes and it shows how using just some bits of wire, heat shrink tubing, and crimp terminals you can wire that bare 7810 chip for use as a gauge voltage stabilizer. I have one on my Mini and I have one mounted on the back of each gauge in my Spitfire.

http://www.adocars.c...mages/v-reg.jpg

[jamiestevenbell]

well its wired. Will it need earthing? I havent tested it yet though

[Dan]

The sender is the earth, that's how it works. The sender is a thermally variable resistor, as the temperature changes so does the current to earth through the sender and that's what the gauge indicates.

[lrostoke]

If it as a hole for a bulb holder then depending on the type of bulb fixing you may need to earth the case.