Page 1 of 1

Voltage stabilizer

Posted: Tue Nov 11, 2025 2:26 pm
by Blaketon
For years I never needed one (In fact, in over forty years, my 1979 MG Midget and 1974 MGB GT V8 have never needed new ones) and my mother's 1978 MGB GT (With us since 2003, when it came to use with 32000 miles) could well have the OE one. In about 2010, my Traveller needed one and I think I am soon to be on replacement number three. The car has the same speedometer and temp/oil gauges as a Mini and I am told that (Nowadays at least) the stabilizers are the same part. I can't imagine it would have been worth making a different stabilizer for cars without the temp gauges (The oil gauge works manually).

It has crossed my mind that a separate stabilizer, for each, may put less strain on the stabilizer BUT, as it is, if the temp gauge over reads and the fuel gauge shows more fuel than I have, I know the stabilizer is playing up. If I have separate stabilizers, I wouldn't know!!

Does anyone know whether there are better stabilizers available, such as solid state types?

Re: Voltage stabilizer

Posted: Tue Nov 11, 2025 2:42 pm
by svenedin
The replacement voltage stabilisers currently available are all solid-state and as such, they are now sold in positive and negative earth versions. The original electromechanical types are not polarity sensitive. ESM sell both versions but the non-polarity sensitive type they sell is second-hand.

Stephen

Re: Voltage stabilizer

Posted: Tue Nov 11, 2025 3:09 pm
by geoberni
The 'original' Smiths Voltage Stabiliser is a bit like the 'original' indicator Flasher units.
They heated a bi-metallic strip designed to open and close at a set rate, within a fairly generous tolerance.

The Voltage Regulator was very similar, the difference being that it is calibrated to open close several times a second, and all those pulses of opening and closing are intended to give an average of 10v .... :o
scope.JPG
scope.JPG (64.07 KiB) Viewed 55030 times
So it's not a surprise they that get temperamental after a while.

These a video on youtube which explains it all, which is where I've lifted that nice image of the oscilloscope trace :wink:
At the end he even explains what the fault is with the one he's opened up.
.
https://youtu.be/WlZekK97ntg

I honestly wouldn't bother with a 2nd hand original, it's unlikely to last very long simply due to degradation of the interior wiring.