Smiths Gauges

[Guest Wozzer]

Hi All,

 

I have a set of Smiths gauges and after reading some other posts I now believe I need a voltage regulator to fit before the gauges.

 

Does anyone know where I can find one thats suitable? If not what 'steady' voltage do the gauges need to work?

 

Thanks

Warren

[Guest paul mercer]

i bought a new set of smiths gauges, and there was no mention of a voltage regulator. I guess they are designed to run on 12v. I've had no problems with them (apart from the fact that when lit, they are all slightly different colours)

 

Paul

[Guest Wozzer]

Hi Paul,

 

These are an old set from a Triumph Dolomite - maybe that makes a difference

 

 

Warren

[Guest salty_monk]

You should find the output from an alternator is already stabilised.

I think it was only the output from dynamo's that needed a regulator to prevent spikes & troughs with engine speed...

[Mitch]

Some (if not all ) Smiths gauges need a ten volt stabiliser,

 

Do a search on the web for smiths website.

 

It says on the box of mine that temp and oil pressure need to go though one

 

Mitch

[IanS]

The battery voltage changes and this affects the guage readings.

The alternator regulator prevents the battery over charging but does not stabilise the voltage. Just after starting a cold engine the voltage can fall below 10 volts for a short time. A fully charged battery will be about 13.2 volts.

Dolomite guages expect a 10 volt energisation.

Smiths instrument regulators are available from many of the vehicle electrical suppliers at shows or by mail order.

[Guest rizla]

under load(should always test a charge rate this way)it should be between 13.8--14.2

[Guest Ant]

You definitely need a voltage stabiliser for the fuel gauge and the temp gauge. The "classic" Smiths range (mini's, dolomites, MG's etc etc) all used a 10v stabiliser. The reason is that 12v cannot always be maintained in a vehicle (engine off, lights on, heated screen on, etc), whereas 10v usually can. You have two choices. choice 1 is to buy a voltage regulator of the same vintage as the gauges (or a modern equivalent). This give a _TIME AVERAGED_ voltage of 10v. Some of the time their output is at battery voltage, and other times it's off, so the average over time is 10v. This is fine for the older gauges which are slow to react anyway. this is a standard vehicle setup.

 

The alternative for those who know anything about electronics, is to use a modern voltage regulator. You need to check the current requirements, and it needs to be 10v too if you're using the original sender units. Something like this from maplin should do the trick:

 

http://www.maplin.co.uk/products/module.as...8067&Products=2

 

I'm not sure how the adjustment of these things works but it should be in the data sheet.

 

Ant

[Guest Greg]

Look here for a diy solution.

http://www.mgcars.org.uk/electrical/replacement.html

 

Greg

[Guest elgey7]

If you want a data sheet for the LM317 send me a mail or PM.

I work for the company that make these chips.

Be careful though these regulators need adequate heat sinks. (Vout - Vin X I = W) (Regulator input voltage - output voltage X the total gauge current = the max power dissipation in Watts). Which means fit a heat sink capable of more than this value or it will pop. There is also a min input voltage (2v to be safe) required to maintain regulation. This is fine when running since the alternator controls to 14.2V charging.

 

Personally I'd try to get the original crude controller.

It's less accurate but much less bother.

 

Regards

Colin