Lotus Elan

Voltage stabiliser

PostPost by: mcclelland » Mon Feb 12, 2018 1:38 am

Hi all.
I have a Plus 2 S130 and I am changing my old standard voltage stabiliser with a modern solid state unit for a constant 10 volt output to the gauges.
My question is... do I still need to use the capacitor in my new set up with the solid state unit ?? or is is just used in the old original set up ??
May thanks for your help in the above.
Best regards, George.
George McC.
1968 S4 Elan dhc.(now sold)
1973 Plus2 S130/5
1994 Elan M100 S2
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PostPost by: john.p.clegg » Mon Feb 12, 2018 6:21 am

George
What capacitor?

John :wink:
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PostPost by: mcclelland » Mon Feb 12, 2018 9:48 am

20180212_094118.jpeg and


Hi John... this green colour capacitor has been on the car since it left the factory...Do I still need it ??

Regards, George.
George McC.
1968 S4 Elan dhc.(now sold)
1973 Plus2 S130/5
1994 Elan M100 S2
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PostPost by: bob_rich » Mon Feb 12, 2018 9:54 am

Hi George

I think some of the original voltage regulators used a capacitor to reduce the effects of the switching action of the regulator. I think they use a bimetallic device that switch the +12V on and off so the average voltage output was 10V. with some accessories that also use a switching action ( such as oil pressure sensors) the switching action of these sensors would clash with the regulator switching action and produce a long duration variation of the gauge reading and I think the capacitor was to try and smooth this out.

the solid state regulator produces a constant 10V output so the above problem won't exist. However the solid-state regulator recommends a small 0.1uF to 0.5uF capacitor close the the input and output pins of the part to avoid any instability.

for example look up the data sheet for say a LM7800 series regulators ( they are all much the same in there recommended usage) and this will confirm the connections.

Hope this helps best of luck

Bob
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PostPost by: john.p.clegg » Mon Feb 12, 2018 10:19 am

The solid state Voltage regulators I built a while ago had the input/output capacitors built in...don't know if yours has,might as well keep the capacitor,it will help smooth the output..

John :wink:
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PostPost by: oldelanman » Mon Feb 12, 2018 11:56 am

The capacitor is for radio suppression.. see para 1a on attached pic .. they were also fitted to coil and dynamo.
20180212_113148.jpg and
Roger
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PostPost by: jeff jackson » Mon Feb 12, 2018 9:19 pm

Hi George,
Please find attached an article written a while back, I'm not sure where it came from.
Please use this as a guide.
I would disregard the input capacitor in the article for a 0.33uF Electrolytic capacitor,at least 16V.
Also put a 0.1uF electolytic capacitor on the output, again select at least a 16V,
As it's a linearregulator make sure that the body is in contact with the metal can of the old regulator so it can act as a heatsink. It should not be dropping that much voltage, so you should be ok in terms of heat.
There is only one way to find out, give it a go!
Hope it helps.

Regards
Jeff 72+2.
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PostPost by: mcclelland » Tue Feb 13, 2018 12:43 pm

Just to say many thanks to all for the information. The article was most useful and I'll be soldering soon.
Best regards, George.
George McC.
1968 S4 Elan dhc.(now sold)
1973 Plus2 S130/5
1994 Elan M100 S2
mcclelland
Second Gear
Second Gear
 
Posts: 134
Joined: 13 Apr 2006
Location: Golborne, Warrington

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