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Topic: DC to DC voltage step down (Read 2309 times) previous topic - next topic

btfdev

Hello Friends

We have an Arduino ready to integrate into an electrical appliance for additional functions. Just want to post a question regarding power, see below for details:

Circuit #1: Electrical appliance's transformer converting AC main (120V AC) to 110V DC
Circuit #2: Need 5V DC circuit powering the Arduino (minimal current needed)
Circuit #3: Also need a separate 12V DC circuit (minimal current needed)

Circuit #1 is the original appliance circuit, circuit #2 and #3 are new requirements. Just wondering if there is a DC to DC step down out there with 2 outputs that fits the job?

Thoughts?

Thanks in advance, BTF


tek1229

I don't know what your trying to do, but do you have the mains(120v AC) available to you for circuit 2 and 3?? A computer power supply is cheap and readily available and provides 5v and 12v.. T

FelixFelicis

Idk what exactly you are trying to do.

But I can give you theoretical answers.

For a 120V Ac to Dc you can use a rectifier.

7805 and 7812 can be used for 5v and 12 v.


dc42

Is it acceptable for the Arduino to have a common ground with the 12v supply? If so, then just get a 12v supply and power the Arduino from it too through the barrel jack or the Vin pin.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

btfdev

Thank you for all your replies.

Let me elaborate further.

Circuit #1: Electrical appliance's transformer converting AC main (120V AC) to 110V DC
Circuit #2: Need 5V DC circuit powering the Arduino
Circuit #3: Also need a separate 12V DC circuit to drive some automotive light bulbs

Circuit #1 is the original circuit of the appliance (AC 120V main, power cable to transformer). Circuit #2 and #3 are new requirements. As mentioned before, we are to "Integrate" an Ardunio solution into this appliance, hence we do not want to introduce a extra/external power supply to user.

Also, these 5V & 12V circuits is next to 110V DC source but physically far from AC main. This is what prompt us to see if there is a device which:

1. Has input of 110V DC
2. Provides dual output of 5V DC and 12V DC

Thanks, BTF

dc42

Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

CrossRoads

Sure, you can get a DC-DC converter that will chop up the DC to make AC, run it thru a transformer reduce it to a more manageable level, and rectify it again into a DC level that can then be regulated to 12V and 5V.

Is there a need for the 110VDC? Be easier to work from the 120V AC.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

MarkT


Here's one: http://www.mpja.com/5V-9A-and-12V-300mA-Cisco-Power-Supply/productinfo/18465+PS/


You realise the original post is asking about DC--DC step down supply?  Probably want somewhat less than 9A at 5V...

I've seen nice Murata units that go from 72V down to 12 and 5, see if they do a higher-input-voltage range?  I couldn't see anything.

A 12V power blob from the mains is a possible solution, followed by 12V to 5V converter or regulator?
[ I won't respond to messages, use the forum please ]

kf2qd

What you need is another "power supply" mainly a small stepdown transformer from 120 12 V AC. Go through a ful wave bridge rectifier and a regulator (7812) for your 12V needs, and through a 5 V regulator (7805)  for your 5 volt needs. All this is assuming you need less than 1Amp of low voltage DC. If you need more at 12V then you would have to size that part of the power supply for the 12V needs and still use the 7805 for the 5 V needs. A few appropriate Capacitors at each stage of the DC would clean it up and make the devices connected happy.

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