View Full Version : 5v supplies for breakout board

29-07-2014, 12:56 PM
Im hoping for a bit of help here,im completely useless with electronics I have a cnc that another lad wired up .
But this time round ive tried to get as far as I can get without posting and cant say im enjoying it lol.
theres an image below of how far ive gotten with it,its for an x3 conversion,feel free to tell me if Im doing something wrong.
the power supply is 68volts and was a kit someone put together a while back for me, drivers are 70v
bobs a cheap kl-db25.
ive overlooked/think I need a 5v power supply to the breakout board and wondered what you recommend I do.
is there anything off the shelf I can use that I could plumb into this supply.giving 5v thanks

Boyan Silyavski
29-07-2014, 01:46 PM
any normal old phone charger, wifi router power supply, etc., just look to be 4-6v , >1A, though as i see your board has no relays, may be >500mA could power it without problem

29-07-2014, 01:55 PM
any normal old phone charger, wifi router power supply, etc.,
thanks fella,i did come across that as a solution elsewhere but it was shot down by some due to not being a regulated 5v.

Boyan Silyavski
29-07-2014, 02:08 PM
Most PSU from 1A and up are regulated in fact. That's how i power the BOB of my last build. I have opened last year for this and that at least 10 and only one of them was not regulated.

29-07-2014, 03:08 PM
I should have some of those knocking around so I will dig em out,thanks

29-07-2014, 03:10 PM
Something like http://www.ebay.co.uk/itm/Skynet-SNP-9013-C-5V-1A-12V-1A-PSU-/281379631739?pt=UK_BOI_Electrical_Components_Suppl ies_ET&hash=item418388727b]this ( [url) [/URL] would give you 5v for the BOB and 12v for limit/home switches, etc. And easier to mount and probably more reliable than a wall wart long term

29-07-2014, 03:18 PM
thanks a lot irving it comes up invalid link but this look to be it http://www.ebay.co.uk/itm/Skynet-SNP-9013-C-5V-1A-12V-1A-PSU-/281379631739? will give that a go ;)

29-07-2014, 04:24 PM
I've got plenty - come and grab one at the weekend if you want. I get them for about 20-50p from the car boot so you can have it for nothing.

29-07-2014, 04:36 PM
just bought a couple of those in the link jon but thanks for the offer ;)

01-08-2014, 03:27 PM
I have checked some old mobile phones chargers 5V < 1A and are not regulated.
Maybe a post regulation to these chargers with an LDO regulator is a solution for isolated power supply.

02-08-2014, 04:53 AM
Possibly, but by time you've bought the LDO reg and other things and assembled it its not worth the hassle and the extra 12v output from these supplies is a bonus.

11-11-2014, 01:14 PM
A couple of months ago I bought a new BoB to replace the fried one originally from MD. The original has been discontinued, so I can't get a plug-in replacement. This is the one I bought http://www.ebay.co.uk/itm/Cnc-Router-5-Axis-Breakout-Board-For-Microstep-Controller-0-10V-Analog-Output-/261633467531?
The doubt that I have is that I intend to connect it to the drivers in common anode mode, but the 5v for this is derived directly from the USB connection (from my computer). I would have expected this 5v to be solely to drive the opto isolators on the PC side. The stepper drivers being given 5v derived from the 12-24v input to the board.

I am a bit wary of putting 5v directly from the computer to the drivers (Tonman PD2064M).

I would welcome advice on this as my confidence has been lowered when I found the direct connection.

My machine has been out of action now for months and, due to illness, I haven't had the mental energy to put it back together.

Cheers Mates,


11-11-2014, 01:30 PM
Two options:

A) use a separate 5v usb 'charger' (wall wart)

B) my preference - use a 24v to 5v buck converter, e.g. eBay item 221546337415 - there are lots like this with either USB or screw terminal outputs.

11-11-2014, 08:22 PM
I have one of these boards but I use it for extra inputs only. I only have it connected to a 24V supply and I can confirm there is no 5v output, so it looks like you have to use the USB as well to get the 5v.

11-11-2014, 09:14 PM
Yes Eddy,
I very much thought so me sen. I only bought it for the spindle 0-10v output, as I have got a couple of these boards http://www.embeddedtronics.com/image/opto/opto_new.jpg. I shall be using one to click relays and sense some inputs. I made 'em up myself so I have spare optos and I have the Eagle files, so I know the circuit.

I just wish I had a circuit diagram for the cheap chinese board - Ah well !



Now back to the Jim Beam therapy for this persistent cold I have had on and off (mainly on) for the last three months :)

17-12-2014, 06:12 AM
I am a bit wary of putting 5v directly from the computer to the drivers (Tonman PD2064M).

I would welcome advice on this as my confidence has been lowered when I found the direct connection.


I have a 24V power supply and rather than regulate down for some pcb's I am considering running a 5v from my PC power supply. Not being to electrical I can't see any reason not to.

17-12-2014, 08:34 AM
The purpose of the opto isolator is to prevent any damaging voltage getting to the I/O pins of the LPT port. You could connect directly from the port to the driver, but it is risky. If you get computers cheaper than decent BoBs then it might make sense to wire directly to the driver. 5v from the computer usb port should only provide power to operate the output pins from the computer. Take no notice of the Line designations, that is only relevant for printers, but the output pins(->) should be isolated with 5v power taken from the computer. The input pins (<-) should be isolated with their 5v supply taken from an external supply.

In the end most things will work, but the risk factors are different.



And Seasons Greetings to all who sail in her.


17-12-2014, 08:44 AM
This is what I used; http://www.rapidonline.com/electrical-power/din-rail-power-supply-dsp10-5-51-4682