Asked September 3 2015

Community Question

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I'm making this thread to gather all the power supply references from other threads into one, neat and tidy thread.

Power supplies:
12v car PC power supply:

This gives you 12V, 5v, and 3v at high amperages, which will power sensors, servos, and lots of lights.
Standard PC Power Supply:

Can be found everywhere! And if you want cheap, go to eWaste and pick out one for free-$20! Just get a high Wattage supply.
Courtesy @Steve_G from @fxrtst's Power supply thread:

"I had a bit of a search for you, and came up with the following fixed voltage supplies which was all from one website called TCR Electronics and are all under 100 bucks. Searching other sites pretty much came up with the same makes and models. The ones I've linked to are the best of the bunch that I think meet some of your requirements. I threw a couple of 20 amp supplies in as well in case anyone else is looking...

40 amp
345 watts
$44.80 for 1 to 9 units (cheaper after that).

40 amp
300 watts

20 amp
150 watts

20 amp
150 watts

32 amp
240 watts

And the smallest I found at a reasonable price, but at 20 amps...

20 amp
150 watts

Anything smaller in the way of form factor, and you're looking to pay out at three digit figures. The one other plus about this website is that they do bulk buy discounts too."
Courtesy @Steve_G from @Askwpccoach's "How Can I Provide Continuous Power To Jd From An Ac Outlet Or Battery That Will" Thread

"So a 7.4 volt, 20 amp power supply is what you will need to have JD working at his best along with a female mini deans socket. This switching power supply is a good example of what you would need, although if you look around, you can find cheaper power supplies. "
Courtesy @Mathprof from his "Usb or Ac-Dc Conversion as a Lipo battery replacement" Thread

"Ok, so a 20 amp supply is a good target. Just looking around a little, I found this:

P/N: RSP-150-7.5
7.5vdc Power Supply
Approx Power: 150 Watts
Max Current: 20 Amps
Enclosed 1U low profile 30mm, built-in active PFC function, built in constant current limiting, LED indicator for power on, adjustable output voltage, and universal AC input range: 85~264vac.
Dimensions: 199x99x30mm
More Info, Quotes, Purchase $36.90 ea."

As for Tips, Give out your own! Post them below! More power supply references? Add them below following the numbering sequence.(Ended at 5)

Now you can reference one thread to give an answer instead of multiple ones with many posts to sort through.
March 22 2018

One thing I wanted to point out for you which is something I touched on in step 7
Multimeters“ in my tutorial you linked to,. You quoted...


For the AC power cord i snipped off the end of a computer power cord (Note: altho i read somewhere that the 'brown wire should be hot and the blue neutral, my multimeter said otherwise and i believed it).

Brown wires in AC are indeed “Live” or “Hot” and blue is “Neutral” (and if present, green/yellow is Earth). But here’s the thing. AC, by definition, is alternating current, so it is not polarised and current flows in both directions. Basically this means that you can actually swap the wires around and most of your AC devices would still work with no damage. This is why your meter said the opersite to what you read about wire colours. But with that said, not only is it good practice to use brown as “Live” and blue as “Neutral”, but there is a safety aspect too.

For an example, I’ll use a table lamp with an in-line switch. Some AC appliances, like lamps, have a switch on just one of the two wires, usually the “Live” wire. The outlet has a “Live” and a “Neutral” wire - the “Neutral” wire is connected to ground somewhere, either at the local sub-station or on the street outside your house. The “Live” wire is at 120V US or 240V UK, compared to “Neutral”.

In the lamp itself, the “Live” wire of the light bulb socket is at the bottom, and the “Neutral” lead is on the sides. Sticking your finger in a “Live” socket (not recommended) with the correct polarity it is much more difficult for someone to accidentally touch the “Live” wire or terminal.

So when using a correctly wired and polarised table lamp, switch and plug, there is a guarantee that the switch will disconnect the supply voltage on the “Live” side of the lamp. If the polarity is reversed, then the entire appliance is still live and energised even when it is off, and could be dangerous if you were changing the bulb and happened to touch the metal side of the bulb... as you will get seriously zapped.

DC (direct current) has to be connected the CORRECT way only.

So just for good practice, I’d suggest swapping your blue and brown wires to where they should be on your power supply (as long as the mains plug is wired correctly too).

Hope that helps.:)
March 22 2018
Hi Steve G. Thank you for the explanation -- yes that is very helpful and I did not fully understand that set of issues, so I have a better handle on it now -- much appreciated!
However, my conclusion is still that the cable itself was mis-wired in terms of the blue and brown cable-color, and I had a bunch of measurement photos to show you in order to try to prove it, then I remembered, hey I still have the severed plug -- here it is:
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Blue=LiveHot -- What do you think?

And Hi to Nomad 6R too -- this power supply does not have a switch (prolly you were thinking along these same lines as Steve G?).

Thanks for your feedback and any other comments are welcome!

Richard 'twitch' R.
March 23 2018
this is a great topic.learn alot thanks rregister and steve G

here is a link for all kinds of switshes wires cables.these are up to 12 volt.

on/off swiths

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March 23 2018
Hey there Nomad 6R
Looks like this inline toggle switch supports 0-2A current
and i believe the servos will draw much more than that for short periods during inrush.
I have put a simple plug strip with on/off switch on the AC side for the power supply and that seems to be working so far.
best regards -Twitch
April 5 2018
An update about using this Mean-Well RSP-150-7.5 supply -- It works reliably on my 10-servo robot, but using the power supply on my JD i was experiencing a brown-out once and a while (approximately once or twice a day), and this typically resulted in JD disconnecting from my wifi network.
I tried the solution posted by Jeremie and DJ (in post #15 of
using two 1Farad 2.5V Aerogel caps in series and that seems to have solved the problem: i haven't seen a brown-out since. - Thanks for that thread and i hope others find this helpful. -Richard 'Twitch' R.
Here are some photos:

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