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Registered Member #3505
Joined: Sun Dec 12 2010, 06:03AM
Location: Albuquerque NM
Posts: 108
I have a project in which I'm using ~30 smart servos http://www.robotshop.com/content/PDF/manual-drs-0101.pdf. These servos can pull about half an amp when they are in full swing. Since this is a desktop toy I'm not really using a battery and would like to make a 10.5 volt/30 amp supply to ensure I have room to expand in the future. I've look at several schematics of DC-DC converters using a buck/boost converter. Would this be a good way to go or should I look at a different avenue? Thanks in advance.
Registered Member #2901
Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837
Buck/boost isn't isolated, that shouldn't be an option.
A transformer based switching converter which goes from rectified line voltage to 10.5 Volt would certainly be smallest, but it's not a trivial design.
People have modded server power supplies (which are switching converters) to get high current 12V supplies, which you could drop to 10.5 with a linear regulator.
Registered Member #3505
Joined: Sun Dec 12 2010, 06:03AM
Location: Albuquerque NM
Posts: 108
Yup. I would like to use mains and the dc to dc part comes from the rectifying of mains voltage. If you copy the link into your address bar it works. Since I'm using mains and I only need ~10.5 volts I guess I only need a buck converter. Unless there is an advantage of using a boost/buck.
Edit*** I made this post before I saw your post. I need this power supply to be as efficient as possible. When this project is done the mains voltage will be replace with ~170 volt battery supply.
Registered Member #2901
Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837
If it's going to run off a high voltage battery in the end you could use an isolated transformer in the mean time, this allows you to ground one of the inputs for your buck converter so you can be sure you aren't putting mains voltage into your robot (relative to ground, not necessarily a problem for the robot's circuitry ... but it might be a problem for you if you go poking in it expecting only 12 Volt).
At these kind of huge ratios normal buck converters aren't terribly efficient though.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
I would probably go for PC power supplies, the most watts/cost AND isolated. They all convert ac to dc for the output switcher so if you start with a 120 Vac input smpsu later you can just connect your 170 Vdc battery to the dc bus. This is of course true of all modern cheap smpsu.
Better smpsu have a pfc front end which may not be so easy to bypass so non-pfc smpsu is what you're looking for.
I would find difficulty buying the parts for the cost of a PC smpsu,
Almost all smpsu can be easily modified for lower output voltage (usually just one resistor) so save time, cost, frustration and legal liabilities use ready made smpsu, even if you need 2, 3, 4 units as opposed to one large one, ... call it a redundancy feature / expandability function!
Registered Member #2390
Joined: Sat Sept 26 2009, 02:04PM
Location: Milwaukee Wisconsin
Posts: 381
Check out MeanWell Power supplies, they're as cheap as it gets and should work for you. I have a 12vdc 30amp meanwell running some tec modules and its been bulletproof for over a year now.
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Robotics power supply questions
