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Alphadog
Andrew Morris

(3 posts)

Registered:
05/06/2014 07:57AM

Main British Car:
Voltage Stabilizer - rebuilt per article - question
Posted by: Alphadog
Date: May 12, 2014 11:54AM

I enjoyed the article by Curtis regarding the voltage stabilizer and decided to rebuild mine (on a TR6 speedo) - I used the LM2940T-10.0 - but skipped the LED and resistor as I don't plan to ever get back behind it.

I noticed that if I supply 14 volts from an old train transformer I get about 12V out of the stabilizer - even though it is a 10.0 "model" - is this because there is no load on it (just bench testing). I have an old mechanical stabilizer and it shows a fairly even 10V. I thought maybe I overheated the first one, so i bought a few more (only $1 each locally) but they all seem to test the same.

Any suggestions?

Thanks,

Andrew


DiDueColpi
Fred Key
West coast - Canada
(1365 posts)

Registered:
05/14/2010 03:06AM

Main British Car:
I really thought that I'd be an action figure by now!

authors avatar
Re: Voltage Stabilizer - rebuilt per article - question
Posted by: DiDueColpi
Date: May 13, 2014 03:44AM

It's reacting that way because the "old train transformer" is supplying ac current and the stabilizer is acting more like a rectifier than a regulator.
Essentially it sees 28 volts rather than 14 and can't deal with the excess effectively.
Heat sinking is critical, because as you probably noticed. These little critters get really hot, really fast, and burn up quickly.
When used as Curtis described they work well and are dead reliable.

Cheers
Fred


Alphadog
Andrew Morris

(3 posts)

Registered:
05/06/2014 07:57AM

Main British Car:
Re: Voltage Stabilizer - rebuilt per article - question
Posted by: Alphadog
Date: May 15, 2014 07:26AM

Hmmm I thought my transformer was dc out. But it could be AC.

I left the heat sink on, but soldere to the ground leg instead of bolting it to the case. Do you recommend bolting it the housing to increase the heat transfer capability?

Thanks!
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DiDueColpi
Fred Key
West coast - Canada
(1365 posts)

Registered:
05/14/2010 03:06AM

Main British Car:
I really thought that I'd be an action figure by now!

authors avatar
Re: Voltage Stabilizer - rebuilt per article - question
Posted by: DiDueColpi
Date: May 15, 2014 12:07PM

I would fasten it down just to be safe.

Cheers


Alphadog
Andrew Morris

(3 posts)

Registered:
05/06/2014 07:57AM

Main British Car:
Re: Voltage Stabilizer - rebuilt per article - question
Posted by: Alphadog
Date: May 16, 2014 09:45AM

BTW - checked my power supply it is labeled 14V DC and that is what multimeter shows... I guess i need to wait until my Dash is finished and i can hook up gauges and sending units and then measure the voltages.


MGBV8
Carl Floyd
Kingsport, TN
(4512 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: Voltage Stabilizer - rebuilt per article - question
Posted by: MGBV8
Date: February 02, 2016 06:56PM

For those that want to study the Smiths Voltage Stabilizer in a bit more detail, I came across this article.

[www.minimania.com]


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6470 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Voltage Stabilizer - rebuilt per article - question
Posted by: BlownMGB-V8
Date: February 03, 2016 12:03PM

I've used the LM317T. Probably have one on my car now. It works well. You can occasionally buy solid state regulators ready made in the old case for about $15 or so. (Price has probably gone up.)

Jim



MGBV8
Carl Floyd
Kingsport, TN
(4512 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: Voltage Stabilizer - rebuilt per article - question
Posted by: MGBV8
Date: February 03, 2016 12:36PM

More from Paul Hunt's awesome website.

[www.mgb-stuff.org.uk]


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6470 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Voltage Stabilizer - rebuilt per article - question
Posted by: BlownMGB-V8
Date: February 03, 2016 06:47PM

Just as important as adjusting the voltage is adjusting the gage. More so really. Most gages of this type have adjustments for zero and full scale that you can tweak with a 1/8" flat blade screwdriver. Done right, you can have your gage accurately reading empty and full. In between is of course not so accurate usually, but you really do want to know when the float hits bottom.

Jim


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