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Instrument Voltage Stabiliser


rogerguzzi

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Hello Learned Friends

                                    I said I would convert one for a mate for his TR4 that is negative earth.

I did my own on Spitty years ago and it works fine but the old Brain has Faded a bit since then and I can not find any notes?

So is a L7810CV ok(I have several) with the 12v on the in leg(1) and 10v out leg (3) and leg (2) earth and the the tag?

Some of the circuits show 0.33uf on leg 1 and 0.1uf on leg 3 ?

I do not remember fitting these to mine?

So how important are they?

Roger (brain Fade!)

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The capacitors are not crucial in this application Roger - the one on the output gives better transient response if the load changes suddenly - which it won't.  The one on the input helps with noise rejection but the instruments won't care much about a bit of noise on the output.  After all, the original bimetallic 'stabiliser'  was switching on and off all the time. 

 

 

Edited by DeTRacted
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On the USA TRiumph Experience forum there was a concern that the LM7810 with 12V going in may not give the 10V coming out.

However there would normally be something like 13V going in which should be enough.

Go for it Roger

 

Roger

 

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3 hours ago, Martin said:

I use the LM7810 since years. No problems.

Hello Martin

                    I think it must be a LM7810 in my Spitfire as I found 4 of them in the electronics boxes?

It must have been in there for at least 8 to 10 years I think?

Roger

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8 hours ago, RogerH said:

On the USA TRiumph Experience forum there was a concern that the LM7810 with 12V going in may not give the 10V coming out.

However there would normally be something like 13V going in which should be enough.

Go for it Roger

 

Roger

 

Hello Roger

                   I have built it in to the smiths case and I tested it on a variable power supply I turned it down to 11.5volts and it still gave 10.15volts and the same at 12v ,13v

No load but I do not suppose they draw much power ?

Roger

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Curious as to why you wouldn't just buy a negative earth one for a TR5/6 (visually idential) and save the hassle :huh:

However out interest I did a search and found this link which replaces the original mechanical bimetallic innards with a solid state one.

The author implies that this is because the originals are unreliable but I have to admit that I have never had one fail even 50 years or so old.

This is quite interesting though and makes one think.

http://www.britishv8.org/Articles/Voltage-Regulator.htm

 

Edited by Escadrille Ecosse
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12 hours ago, Escadrille Ecosse said:

Curious as to why you wouldn't just buy a negative earth one for a TR5/6 (visually idential) and save the hassle :huh:

However out interest I did a search and found this link which replaces the original mechanical bimetallic innards with a solid state one.

The author implies that this is because the originals are unreliable but I have to admit that I have never had one fail even 50 years or so old.

This is quite interesting though and makes one think.

http://www.britishv8.org/Articles/Voltage-Regulator.htm

 

I suppose you could why do we repair anything we could just buy or mess with Old Cars?

He said it was faulty did not check and the LM7810's are pence!

Plus not sure of modern ones quality!

Roger

Ps how many hours on the bonnet!! Ha Ha

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The TRiumph Experience forum in the USA do not like the USA Moss solid state stabiliser for its unreliability 

They have a chap that maskes them for a small fee.

I have had one working for about 8 years with no problem

Why not make your own, if you can.  I do my own on lots of TR things - enjoyment.

 

Roger

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  • 4 weeks later...

Hi,
the LM78/79xx are all old hat now. Everything is digital today & much more efficient.
You can buy a PCB with an XL6009 IC that will accept a wide input voltage from 5V ~ 32V and provide a fixed (Adjustable) output Voltage from 1.25V ~ 35V. It will not care if the input voltage is higher or lower than the desired output voltage.
Cost about a quid.
Adjustable output allows you to trim the 100% gauge reading.
Cheers,
Iain.

6009.JPG

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True but on the other hand,  in that application efficiency is entirely irrelevant as is absolute accuracy of the gauges.  (Added to which if there are more than one gauge, you'll  probably only get one of them reading correctly by adjusting the supply voltage) .

 Being 'old school' I am always wary of using 11 components where one will do the job.  :blush:

 

 

 

Edited by DeTRacted
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