voltage stabiliser

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kenfoster
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voltage stabiliser

Post by kenfoster » Mon Aug 06, 2018 2:16 pm

Hi, can some kind soul tell me what voltage I should have going to my voltage stabiliser? I have 8.45v in, and on the out terminal I have about 2.45v I was expecting 12.5 v supply and 10v out.... I have disconnected the loom plugs which are hidden behind the glove box area, one was quite dirty. One of the plugs cured a previous fault. (see my last post)
My fuel gauge and low fuel warning light don't work. I would attack the sender unit but I need to assess the correct functionality of the voltage stabiliser first.
thanks in advance ken



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voltage stabiliser

Post by Roger Pennington » Mon Aug 06, 2018 2:37 pm

I think those expected figures are correct, however, (assuming it's the original stabiliser) note that it's quite difficult to measure the output accurately, as they work by switching rapidly between on and off, giving an average of 10v.


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voltage stabiliser

Post by kenfoster » Mon Aug 06, 2018 2:43 pm

Thanks Roger, so I should be getting 12.5 at the supply wire. If I've only got 8.45v in then I must have a short or bad connection between battery and VS. Until I have 12,5 supply I can't therefore expect any more than the 2.5 output....Is that fair to say?
Cheers ken



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voltage stabiliser

Post by AJL Electronics » Mon Aug 06, 2018 2:49 pm

Standard ones are bimetallic and rely on the heating of a coil. If you are not providing the full 12V that will not happen, so I would expect either nothing, or the input Voltage.


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voltage stabiliser

Post by kenfoster » Mon Aug 06, 2018 2:55 pm

Ok thanks, so I need to establish 12v supply.
cheers ken



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voltage stabiliser

Post by kenfoster » Mon Aug 06, 2018 2:59 pm

Incidentally; there is white plastic component with wires either end between supply and VS input. It looks like an anti surge fuse maybe??? anyway I took the reading of 8.45v with it removed so it wasn't having an effect.
ken



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voltage stabiliser

Post by Peter S » Fri Aug 31, 2018 4:16 pm

A slight hijack but - About to replace my VS and noticed I have a capacitor on 12v side. This is not on Peter's wiring diagram. I assume not necessary except possibly for radio suppression. Could somebody confirm this please.
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Post by willholderogri » Fri Aug 31, 2018 5:00 pm

That is correct


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voltage stabiliser

Post by scimjim » Fri Aug 31, 2018 5:18 pm

It’s shown on the 5a wiring diagram but not the 6.


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Post by David Tew » Fri Aug 31, 2018 6:03 pm

A capacitor across the input (Vin-eth) will prevent switching 'noise' being fed back into the car wiring, one across the output (Vout-eth) will smooth the voltage to the gauges. Both are probably worthwhile, especially if you fit any moving-coil gauges, although the radio should already have a choke on the 12V supply to block any noise.

The white object you found inline with the input could be a choke which will have a similar affect to a capacitor on the input, albeit by blocking AC ripple rather than shunting it to earth.

Even better, once you get a proper 12v on the input use a solid-state regulator such as an LM7810. No need for suppression and you will be able to measure the output voltage. :wink:


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Post by AJL Electronics » Fri Aug 31, 2018 6:36 pm

David Tew wrote:
Fri Aug 31, 2018 6:03 pm
Even better, once you get a proper 12v on the input use a solid-state regulator such as an LM7810. No need for suppression and you will be able to measure the output voltage. :wink:
A7810 still requires input and output caps to stop it taking off.


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voltage stabiliser

Post by David Tew » Fri Aug 31, 2018 7:14 pm

AJL Electronics wrote:
Fri Aug 31, 2018 6:36 pm
David Tew wrote:
Fri Aug 31, 2018 6:03 pm
Even better, once you get a proper 12v on the input use a solid-state regulator such as an LM7810. No need for suppression and you will be able to measure the output voltage. :wink:
A7810 still requires input and output caps to stop it taking off.
True, but not for radio suppression.

Perhaps an even better and easier option is an adjustable buck converter such as THIS. Very cheap, an easy fix and no heat or noise issues. :)


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voltage stabiliser

Post by peter freeman » Fri Aug 31, 2018 8:58 pm

You will find capacitors all over he place in classic cars - that's because the radios of that age were all AM and the AM radio is affected by noise - its very rare for a FM radio to be affected in the same way.



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Post by Peter S » Sat Sep 01, 2018 9:36 am

Thanks for all the replies.
As my knowledge of electronics very basic I've ordered a solid state direct replacement, which should be OK with my current 11.45v input, as it can supposedly cope with an inlet as low as 10.5v.
The radio doesn't work (another wiring nightmare) so I'll give the capacitor a miss for the present.


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Post by AJL Electronics » Sat Sep 01, 2018 9:43 am

Peter S wrote:
Sat Sep 01, 2018 9:36 am
Thanks for all the replies.
As my knowledge of electronics very basic I've ordered a solid state direct replacement, which should be OK with my current 11.45v input, as it can supposedly cope with an inlet as low as 10.5v.
The radio doesn't work (another wiring nightmare) so I'll give the capacitor a miss for the present.
The replacement you have ordered will be one of the half hearted types I imagine. There are two main types, an SMD regulator on a small PCB in a similar to original case which has no stabilisation components nor heatsink, or the LM7810 with flying leads and a bit of heatshrink. I am still waiting to see one built to the correct spec, with stabilisation capacitors.


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