In this case you get a programmable power supply able to give you up to 50v at up to 20 amps output.
But doesn’t that seem a bit daft, needing a power supply to feed a DIY power supply? Nowhere near as daft as it seems – read on – it gets a lot better…
You may have seen a video on an earlier version of this where an output capacitor burned out – well, that’s been sorted out – but what you might not have seen is just what this inexpensive supply can do!
SO in the simplest sense, you get the package, connect the front panel to the control panel (the leads are keyed and marked – you can’t go wrong), stick the two in a box, add output terminals and some form of DC power (I plan to use a 30v 3a laptop supply as I don’t really need the higher voltages) and you’re done. My current little desk supply can only manage a couple of amps.
The front panel – which I have to say is VERY pretty, allows you to set up not only the maximum voltage, or maximum current but also the maximum power. Not only that but you can also set up to 10 memories for easy recall. So this immediately makes for a small, neat and very useful supply.
But, it gets a WHOLE lot better than this! The kit turned up today from the designer (Glen) of the product (here’s the product link) and in the box was what looked like an FTDI – i.e. UART to serial converter along with a Bluetooth equivalent (pass code 1234, just looks like a UART COM port). Thanks for this, Glen.
So here’s the thing, Ok it’s a neat power supply but I always want more, so I went to this site in search of software to make use of this serial connector - and downloaded the PC software accordingly.
I loaded up the software, pushed the serial connector onto the board and connected to a USB connection on my PC. I fired up the software and… it worked.
Not only does the PC software work well, but a document is also provided on that link with the communications protocol – and Node-Red fans will be pleased to note that the protocol is MODBUS and there’s a Node-Red node for that – called node-red-contrib-serial-modbus
Now THAT opens up a whole new world. Note in the image of the PC program above, the voltage I adjusted using that large knob at the top, would never go past 29v as my input voltage was only a little higher than that.
But it does not stop there, the second tab “advanced function” allows for a whole boatload of auto testing, data group operations and more. This truly is a nice piece of work and it is free to download.
When the PC is controlling the board, the front panel controls on the supply are deliberately disabled. Makes sense. You can even control the LCD brightness from the PC.
I have to say – I am dead impressed.
Stable output voltage
Of course – now you’re thinking – well, that’s all very nice but how does it perform as a power supply. Right now I’m awaiting some test gear but I set the current maximum to 1 amp, voltage at 5v and applied a 2 ohm load. Sure enough, the voltage immediately dropped to ensure no more than 1 amp flowed.
When I removed that restriction the same load (not precision resistors, just ones I had lying around) – saw 2.4 amps flow through the resistors – a total of 12w of power… all of which sounds about right. The output voltage stayed rock solid at 5v. I could only do this for a few tens of seconds as my finger were burning holding the resistors. The supply itself remained freezing cold and the fan stayed off during this time.
To test the other extreme, I set the output to 20ma and attached a small (disposable) LED to the output – and turned the unit on – sure enough – soft start and the LED came on nicely.
Once I get it in a box and get a decent scope on it I will update the blog accordingly – up to now, no gripes at all.
Here is the link - https://rdtech.aliexpress.com/store/923042
I ended up with a case for the 5005 unit (50v 5a) version featured elsewhere on the blog and swapped cases as I’m really impressed with the 5020 version. The case allows for the serial connection as you can see here. The little serial adaptor fits neatly on 2 standoffs.
The boxed unit looks great. As mentioned earlier the fan that comes with the box is just a tad noisy, I fixed that by dropping the voltage to it a little using a couple of diodes. Of course that may affect it’s ability to dissipate heat on heavy load but then the 5020 unit has it’s own fan on board as well. Time will tell. It definitely has a place on my workbench and with the ability to monitor voltage and current on the PC… lovely.
Stand-alone Power Supply Unit from Banggood
Of course, Ruideng do a range of supplies and one of the smaller ones is particularly interesting. If the powerful unit above all sounds a little over the top, there is also a little stand-alone version that all fits in the front panel container and this one came from Banggood. This unit does 20 volts maximum at 3 amps…. and is called the DPS3003 – it is VERY neat, needing just 20v DC max input. There is no serial or Bluetooth but then it is also cheaper, does not have a separate control board (it is all in the front panel) and would fit in a much smaller box. Here is the link if you’re interested.
Banggood also do other supplies of course – I’ll leave this link here for those interested.
In the coming weeks I will have a better scope to look at the output of these little wonders as well as a programmable load so we can see the output under various loads. Keep looking in.