Vintage Smiths voltage stabilizer teardown

[@madscientisthut]

Very interesting way to "regulate" voltage back then. Yep a modern sub 2 dollar dc-dc buck module would definitely fix that. I would use a LM2596 module.

[@smellsofbikes]

I think the modern replacements still use a linear. I replaced this with a buck module, but don't remember which one, in a little stamped metal enclosure I made and bolted to the back of the dashboard.

[@MrWaalkman]

@@smellsofbikes The modern replacements not only use a linear, but a through hole part on a surface mount board. LOL!

[@MrWaalkman]

Nice rundown on these. I didn't expect you to break out the LeCroy however... :)

[@smellsofbikes]

I do love my LeCroy!

[@MrWaalkman]

@@smellsofbikes I should have known something was up when I saw the BK. My gear is a mix of HP (Logic Analyzers, Frequency generator, Data Acquisition unit - the oldie but goodie HP stuff) and Rigol scopes. And of course meters, soldering/desoldering stations, and whatnot. And I surmise from your site that you are in Colorado? I grew up in Black Forest outside of Colorado Springs. What brought me here was a recommendation based some searches that I made for a "modern" version of these. Wegs Garage (TR4 channel) ran into the same problem as you and bought a replacement for theirs. But I suspect that Moss shipped them a positive ground version by mistake. It blew, of course, and the teardown revealed that it was a through hole device mounted as if it were a surface mount device. :)

[@smellsofbikes]

@@MrWaalkman 90% of my stuff is HP since I used to work for them: all 1980's stuff. I used to go to summer camp in the black forest. There are modern replacements but as you've found they can have polarity issues. I put a buck regulator in this car for a while, during repairing this one, and now have a modern linear regulator doing its job but since the vintage one is repaired I could always chuck it in again.

[@MrWaalkman]

@@smellsofbikes I remember the HP place in the Springs, I can't remember what they made. As for summer camps in Black Forest, all that comes to mind is La Foret. No summer camp for us, we just played in Kettle Creek. :) So what wire did you use to repair your Smith's? Or did you just pull the bad spot away from the bar to isolate it? And it looks like it uses Litz wire.

[@scottneels2628]

Hi, Can you please give some guidance on what you replaced this with. I have one the same on my temperature gauge on my 2500 tc & S which I'd like to replace. I don't know what parameters to search for a suitable buck regulator? 12 down to 10 volts but what current, do I need to limit that?

[@smellsofbikes]

It's a tiny amount of current required. Most Spitfires need a supply for both the fuel gauge and the water temperature gauge. (I have an aftermarket WT gauge so I don't know the current the stock one takes.) But any cheap switching buck regulator should work. You don't need to limit the current.

[@scottneels2628]

@@smellsofbikes Thanks heaps.