# DC-DC converter - Variable Input - Constant Regulated 12VDC output?

#### pscammp

Joined Feb 22, 2016
24
Hello all,
I'm new and hoping I can get some good advice for an up and coming project, I hope someone can help me out here ?

I have a 12V 75Ah Leisure battery which is to be the main power pack for a project I am about to start. I know that once this thing is charged up it could produce way over 12V but as it runs down it could only produce 11.9V.

One of my pieces of equipment which is an astrophotography camera needs a regulated DC supply of smack on 12VDC, it defiantly can not go above 13V. I have been looking at DC-DC converters but have found out that they either step up or step down but I have not been able to find one which will take a variable input voltage and still maintain a constant 12VDC output if the input voltage is higher or lower than the output voltage. I need to be able to cover a minimum of 30W @ 12VDC for the output.

Is it possible to make or purchase a module (as small as reasonably possible) which will take a variable input voltage of, lets say ranging from 10-15VDC and output a constant regulated 12VDC @ min 30W (50W would be safer probably) ?????

Can It Be Done ?

Many Thanks for any useful advice

Regards
Paul

#### Alec_t

Joined Sep 17, 2013
11,817
Welcome to AAC!
What you are looking for is a '12V buck boost regulator'. Google gives many hits.

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#### Evanguy

Joined Dec 21, 2014
81
Ebay has them for around 1-3$us. Some come with heatsinks and lcd screens to view output voltage. they are about 5$us

#### pscammp

Joined Feb 22, 2016
24

Just learned something new in that the x5 'Boost' DC-DC converters will be no good if the battery
drops below 12V for a 12V output LOLOLOL

'Automatic Buck and Boost' is where I need to be so I'll have to pop the Boost's on Ebay when I get
them from china.....How annoying

I shall be going for the one's which display the output voltage on the PCB and the x6 voltage displays
I got can also go on Ebay too. This will save me having to painstakingly cutting out 6 holes in my tool
box....Yum Yum

I very much appreciate the help
Paul

#### AnalogKid

Joined Aug 1, 2013
8,833

ak

#### Hayukan Rise

Joined Feb 23, 2016
1
Hi. I'm new to the site and new to circuitry but... If your input varies but you want your output to be constant could you try doing an inductor to power transistor to a 12v zener diode? That should increase your lower input and then limit it to only 12v to your output. Just a thought.

#### Bordodynov

Joined May 20, 2015
2,745
TRACO POWER TEN 50-1212 ==> Input 9V-18V Output=12V Ioutput_max=4.167A, 1" x 2" x 0.4".

#### pscammp

Joined Feb 22, 2016
24
Analogkid,
Seems buck/boost converters are few and far between which will cover all my power needs AND have a built on display for the voltage output value, I see the following one from China although it's a bit pricey as I need 6 of them (not all need 6 Amp though, some only need 1 Amp):

http://www.ebay.co.uk/itm/38V-6A-DC...787789?hash=item542093760d:g:f08AAOSwWnFWARJ9

Maybe another option is to have one's without displays of which there seems to be many, hook up some wires from all their output sides, bang them onto a 6 way rotary switch and have a single Volt display unit hooked up to the switches common and I can select each one in turn to set/monitor their output ?????

Bordodynov,
Just looked at the TRACO POWER TEN 50-1212 on the Farnell site and it says the minimum input voltage is 18V - No Good

Cheers Paul

#### Bordodynov

Joined May 20, 2015
2,745
Cheers Paul. I used datasheet ==> Input 9V-18V. Read original.

#### dante_clericuzzio

Joined Mar 28, 2016
227
TRACO POWER TEN 50-1212 ==> Input 9V-18V Output=12V Ioutput_max=4.167A, 1" x 2" x 0.4".
Hey i am interested in this but it's quite a price to pay for...is there any chip that can step up and output current more than 10 A?

#### tcmtech

Joined Nov 4, 2013
2,867
No.

#### Bordodynov

Joined May 20, 2015
2,745
Hey i am interested in this but it's quite a price to pay for...is there any chip that can step up and output current more than 10 A?
See (not low cost ~210 euro)