12V Regulator

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I would like to build a 12V regulator that will allow me to place a
cigarette lighter type connector on any supply from 12V up to 24V and be
assured that I'm always going to have 13.8V at the output.

I need a circuit that's going to regulate anywhere between, say, 12V and 30V
down to 12V at up to 10A?

Any assistance would be GREATLY appreciated.

Cheers,

Cam



Re: 12V Regulator



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What you are looking for is a DC-DC Converter. Such converters are
normally switch mode PSU's to keep size down and efficiency up.
Unfortunately you can't get them with a 12V - 30V input range. A
nominal 12V input unit will allow voltages from 11 - 16V to be used
while a nominal 24V input unit will allow voltages from 19 - 36V to be
used. Also, most units don't output 13.8V but it is possible to adjust
a nominal 12V output unit to get this voltage.

There may be a problem in finding a unit which takes a nominal 12V
input and outputs a nominal 12V (adj to 13.8V) at 10A. Most units on
the market for higher power usually require 24V.

For your requirements you would need a minimum 150W unit, or 200W unit
preferably.

Mean Well make a fairly good range at low cost
http://www.computronics.com.au/meanwell /

Re: 12V Regulator



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Thanks Ross,

I did Google for such a beast but was unable to find anything. I've even
tried searching for DIY stuff to no avail.

I would prefer a single device that would regulate any input from 12V to
about 30V back down to 12V at up to 10A.

Basically I want to build a black box that I can connect up to a DC supply
(from a vehicle) that will always give me 12V output. If it was really
fancy, I would like to be able to sense the input voltage and disconnect the
load once the input voltage reached a predetermined voltage.

Cheers,

Cam



Re: 12V Regulator


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Now the question is do you want to use it in a car or while camping ?
  perhaps two devices like a dc or ac input device for the car and a
small genny as well ?
  either way what you're asking for exists but is VERY expensive and I
have never seen one outside the military .

Re: 12V Regulator



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I don't know of a readily available off-the-shelf unit which covers
the wide input range and output power you require. Gaia do make them
in a 150W Hi-Rel module but you can expect to pay big bickies for
them. I doubt that the nominal output voltage is adjustable at all.

http://www.gaia-converter.ca/content/datasheet/MGDM150.pdf

Some of the newer IC's such as
http://focus.ti.com/lit/ds/symlink/tps40200.pdf will cover this range
but until they start appearing in commercial products you will have to
roll-your-own.

Re: 12V Regulator


On Tue, 19 Dec 2006 11:17:50 GMT, Ross Herbert

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PS: You can add an external trimpot to get +10% so if 13.2V is ok then
it might be an option.

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Re: 12V Regulator


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Well, being realistic, would you care to tell us what what you are
powering and where you think youare going to use it?

Re: 12V Regulator


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I had a similar need although only to cope with 12v car systems, so I
first stepped up to 15v then regulated back to 12v, worked out nice and
steady.

If you have a stepup section that has a large power diode so it is
bypassed if suffiecient voltage is comming in, then have a step down to
get your 12v, you should be able to keep it fairly efficent.  I used
lm2576 and lm2577 with large and fast switching transistors to carry the
heavy amps.

given the cheap cost of inverters it may not be cost effective to build
your own anymore.

    cya,    Andrew...


Re: 12V Regulator


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Farnell have one that might suit if you are happy with half that
current:
850-1165 is a 9-36V input, 12V/4.16A output $207
There is smaller one too 500-1018 10-40V input, 12V/2.5A output, but
more expensive.

Maybe check RS components too.

Dave :)


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If you look at the info on Farnell 850-1165
http://au.farnell.com/jsp/endecaSearch/partDetail.jsp?SKU85%01165 you
will see that it is a nominal 24V dc input with a minimum of 18V.
Other than that, Farnell no longer stock it. It is replaced with
117-6751 but that still doesn't help.

Re: 12V Regulator


Thanks for all the advice.

Basically, I spend a lot of time away from a reliable mains supply but with
access to vehicles (12V and 24V) and batteries (12, 24 and 28V).

I need a regulator that can regulate any of these to 12V so that all I have
to do is connect the regulator to any of the available sources and know that
I will always have a regulated 12V supply regardless of the input.

As the batteries are lithium, they don't like to be completely discharged,
so the ability to disconnect the load if the battery vltage falls below 18V
would be good.

As I want to supply anything up to a car radio, I will need something of
supplying up to 10A.

I'm happy to build the device myself, I'm just trying to source some circuit
diagrams from those more in the know.

Cheers,

Cam



Re: 12V Regulator



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There are vehicle dc - dc adapters (converters) which might be
suitable. Powersolve (UK) make a 75W version with 11 - 28V input which
will supply 6.25A at 12V.
http://www.powersolve.co.uk/jkcm/cache/fl0001010.pdf

Other manufacturers eg. Lind Electronics
http://www.lindelectronics.com/ make 12 - 32V input models for laptops
but I doubt there are any laptops which require a 12V input these days
so I doubt they will have anything suitable.

One other point to consider is that the 12V cigarette lighter socket
does have current limitations. Once the current from the socket
exceeds about 12A the plug/socket will get quite hot after a while.
This indicates a significant volt drop at the connector and internal
fuse and therefore the output capability of any dc-dc converter will
be limited. You also need a good cig plug to withstand the heat - I
have seen the cheap plastic plugs melt after drawing heavy current for
more than a minute or two. Because such dc-dc converters will be, at
best, 80% efficient, the capability of cig plug adapters will be less
than you require - somewhere in the region of 70 - 90W maximum output.


Re: 12V Regulator



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From an interest point of view I put a query to Lind Electronics and
here is their reply.


We have adapters that can provide 12 VDC output with a 12-32 V input.
There are a variety of output mating connector options available. If
you can provide exact information regarding the mating plug we most
likely can provide the adapter with it. We can also provide it with
bare wire leads so you can install your own. The adapter would be
similar to most of our 90 - 100 Watt adapters listed on our web site.
The cost of the adapter is US$129.95 plus US$33.00 for shipping. There
may be additional customs fees when the adapter arrives to you.

You can order by responding to this email.

Provide your ship address.
Telephone number
Credit card number with expiration date.

Thanks,  T. Neville


All up cost to import is $US163.00 ($AU207.40). Just specify the input
connector is a cig lighter plug and whatever output lead you want. You
could not build a 90W unit for less so in my book it is a good deal.

Re: 12V Regulator


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Then the printed catalog is wrong, it shows a 9-36V input range. The
PS50-12-S12 is the 9-36V input range, but Farnell don't have it.

The 459-9021 from RS has a 10-40V input range (if you believe the
printed catalog again), 12V output but only 2.5A.

Dave :)


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