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Topic: three servos, 4 motors, LED's....How do I power all this stuff? (Read 1 time) previous topic - next topic

ifugaopapercraft

I am working on a sculpture that includes three servos, 4 x  12v motors, and 30 LED's. The three servos are running well on a 6v/1.5 amp wall wart. The additional three motors (12v, 500 mA each) will be ready for testing in a few day. Ideally, I would like to use a single power supply for the entire project. Something ready made wold be great but I see no Wall Wart rated more than 2 Amp.  Is there something salvageable? If not, do I have to order a transformer, rectify it from scratch?   If the total is 5 amps, do I make a rail and regulate with 78-- or LM317? 

Krodal

A 78-- or LM317 are for 1A or a little more and they get hot, you might need a heatsink.
A DC-DC converter is very efficient.

Do you use an Arduino and a motor driver ?
If the servos are 6V, you could use a DC-DC converter to 6V and use it for the adapter plug (or Vin) of the Arduino and the servos.

If you can power the leds with 12V or a with second DC-DC converter, you would only need a power supply of 12V.

ifugaopapercraft

Are the DC to DC converters you describe the same as "buck converters?  I am looking at tutorials to understand your suggestion. Are these circuits or a single component?

CrossRoads

Check mpja.com - lots of supplies available, many with multiple outputs
http://www.mpja.com/12-Volt-Power-Supply/products/537/
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.

Krodal

#4
Feb 11, 2013, 09:28 am Last Edit: Feb 11, 2013, 09:29 am by Krodal Reason: 1

Are the DC to DC converters you describe the same as "buck converters?  I am looking at tutorials to understand your suggestion. Are these circuits or a single component?


DC-DC converters is a common name for step-up, step-down, boost and buck-boost converters.
Sometimes it is a small black box (with the components inside), but mostly it is a circuit board.
Some examples: http://www.ebay.com/sch/i.html?_nkw=dc+dc+converter

ifugaopapercraft

To be sure I understand; I could use this http://www.ebay.ca/itm/For-12-Volt-5-Amp-12V-5A-DC-Supply-AC-Power-Adapter-LCD-SHIP-FROM-USA-/181046745793?pt=US_Monitor_Power_Supplies&hash=item2a273a1ac1&_uhb=1#ht_2455wt_945 and regulate with two or three of these DC to DC http://www.ebay.ca/itm/5pcs-DC-DC-Buck-Converter-Step-Down-Module-LM2596-Power-Supply-Output-1-23V-30V-/271091022746#ht_1777wt_702?

Krodal

The second one (DC-DC Buck converter) is okay. If 2A is okay for you.

I have doubts about the first one (switching power supply 12Volt 5 Amp). I bought a few switching power supplies from Ebay, and most of them can not deliver the current and they get overheated and get broken within a few month.

If you would also use a DC-DC converters for the motors, you don't need a regulated power supply. Perhaps you have some DC power supply already ? Or an adaptor of 19V for a laptop.

ifugaopapercraft

So if the total amps is around 5, what should I use for a power supply? Hopefully, something I could find at Goodwill?

CrossRoads

Did you look at mpja.com at all?
They have high current suppllies available.
You could use a 12V, 4A supply and use smaller switching adapters for the lower voltages
http://www.pololu.com/catalog/category/84
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.

ifugaopapercraft

Would this work? http://www.mpja.com/12-Volt-Unregulated-Power-Supply-4A/productinfo/17636%20PS/

ifugaopapercraft

Or would this be better? http://www.ebay.com/itm/12-Volt-5-Amp-12V-5A-DC-Supply-AC-Power-Adapter-LCD-/200774923425

Krodal

The first one depends on the motors. For an unregulated power supply I would prefer to use 15...25 V, and use DC-DC converters to make a good 12V for the motors.
The second one is a brandless cheap switching power adapter again. If you buy that, you probably have to buy a better version soon. Don't try to buy a good 12V 4A power supply for 10 dollars, that's not possible.

If you want something cheap, this one: http://www.mpja.com/12-Volt-Power-Supply-85A-100W-Switching-Hengfu/productinfo/16013%20PS/
But I'm not sure how it will behave without any load.

If you want something better: http://www.mpja.com/12-Volt-Power-Supply-51A-Linear-IHN12-51/productinfo/6609%20PS/

ifugaopapercraft

Sorry, a dumb question: What happens to the unused amps?  Any problem running these motors directly from the power supply? Can both current and voltage be adjusted?  I have ordered DC to DC converters.  Thank you so much for the advice. The typical small, Arduino board driven projects I have worked with before have not been so challenging in terms of power supply.

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