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hunsta
Joined: 09 Sep 2013 Posts: 92 Location: Gympie Qld Australia
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Posted: Mon Jun 25, 2018 11:07 pm Post subject: 6V to 12V guages question |
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Gday all.
I have a 1948 Morris 8 E series. I wish to convert it from 6V to 12V. Now apart from the obvious major electrical components that obviously have to be changed. My question is regarding the dashboard guages.
Now what little lighting bulbs there is need to be changed to 12v. And of cause the speedometer itself is cable run. But mainly what will need to be changed, if anything on the fuel guage ( yes I realise the tank sender will need to be 12V) and temp guage. Or are they run on particularly what power the sender unit sends them.
Apologise if these sound like silly questions. But sparks and wires are not my forte'.
Cheers
Craig _________________ I really am a nice guy. Just ask anyone that hasn't met me. |
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jp928
Joined: 07 Jun 2016 Posts: 249 Location: Australia
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Posted: Tue Jun 26, 2018 6:36 am Post subject: |
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Dont know specifically what you have on the Morris, but.. Apart from light bulbs, most gauges will need changing, unless you provide them with a 6v source from a battery tap at end of 3rd cell. Some cars come with a voltage stabilizer which drops the usual 12V to around 10v to ensure the gauge reading is reliable under conditions where the battery has sagged somewhat - usually a small tin can - some I have seen are sort of thumb sized, on the back of the instrument panel. Fuel and temperature gauges work off reading current flow through a resistance - fuel by wiping across a winding, temp by reading a resistance with a NTC - negative temperature coefficient - resistance goes down as they heat up.
Are you going to 12V for the sake of modern accessories or ? Changing polarity ?
jp 26 Rover 9 |
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hunsta
Joined: 09 Sep 2013 Posts: 92 Location: Gympie Qld Australia
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Posted: Tue Jun 26, 2018 7:07 am Post subject: |
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Thanks for the reply. Im going 12v because I have changed the 6v 918cc flat head side valve motor. To a later model Morris 950cc OHV. So has the be 12v. I guess Ill just have to change the guages.
Cheers
Craig _________________ I really am a nice guy. Just ask anyone that hasn't met me. |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4104 Location: South Cheshire
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Posted: Tue Jun 26, 2018 12:39 pm Post subject: |
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Either isolate the fuel gauge circuit, get hold of a 6v voltage regulator, something like a 7806 (about 50p cost) and supply the sender & gauge fom this supply.
https://en.wikipedia.org/wiki/78xx
or use a fuel gauge and sender from a post war minor, I'm pretty sure the minor fuel gauge (in the speedo) is physicaly the same size as the SE; the face colour will be different, but you may be able to swap them .
Dave |
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hunsta
Joined: 09 Sep 2013 Posts: 92 Location: Gympie Qld Australia
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Posted: Wed Jun 27, 2018 3:44 am Post subject: |
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Thanks for that Dave. And just on another note. I did get those headlight extension you sent me. Thanks once again. Just got to adapt a bucket and find some chrome surrounds to go with them. Hope the ankle healed ok _________________ I really am a nice guy. Just ask anyone that hasn't met me. |
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Clactonguy
Joined: 20 Mar 2018 Posts: 104 Location: clacton on sea
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Posted: Thu Jun 28, 2018 6:11 pm Post subject: 12 v gauges |
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as far as I am aware. ..its fairly simple. to drop voltages by adding a resistor in series with. gauge supply. thus powering with 6v. ( due to voltage drop by resistor). sadly not. electronics minded. so cant say what size you need but ad sure yahoo answers ? or an electrical chat /forum? can. answer as probably a basic 1st year. apprentice. stuff. |
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hunsta
Joined: 09 Sep 2013 Posts: 92 Location: Gympie Qld Australia
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Posted: Thu Jun 28, 2018 10:08 pm Post subject: Re: 12 v gauges |
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Clactonguy wrote: | yahoo answers ? or an electrical chat /forum? can. . |
An "electrical "chat/ forum eh???? Brilliant. Why didnt I think of that? LMFAO.........Sorry couldn't help myself. Thanks guys for the answers. Seems a resistor is te way to go.
Cheers
Craig _________________ I really am a nice guy. Just ask anyone that hasn't met me. |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4104 Location: South Cheshire
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Posted: Thu Jun 28, 2018 10:56 pm Post subject: Re: 12 v gauges |
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Clactonguy wrote: | as far as I am aware. ..its fairly simple. to drop voltages by adding a resistor in series with. gauge supply. thus powering with 6v. ( due to voltage drop by resistor). sadly not. electronics minded. so cant say what size you need but ad sure yahoo answers ? or an electrical chat /forum? can. answer as probably a basic 1st year. apprentice. stuff. | No No No! as most will have noticed, fuel gauges are unaffected by voltage variations, one can not simply drop a resistor in !!!!
Dave |
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