DIN Rail Programmable lab power supply


Anyone browsing the Chinese webshots for electronics, probably has seen those little “DPS” switching power modules.  The latest versions even have Bluetooth and/or USB communication to be controlled or just monitored via an app or Windows application.

DIN rail mount

These DPS modules still need some kind of enclosure and some power adapter to feed them up-to 40V DC. This makes already a bit more complicated to use one of these modules.

Most enclosures also are quite large, compared to the modules themselves and require some self-made fixture to mount the primary power supply.

I found quite a small set of components anyone can mount together and use a laptop-like adapter to power the boards.  On to of that (actually the bottom 🙂 ) I found a nice board with 4 LM2596 switching power modules to output 4 fixed outputs of 3.3V/5V/12V/ADJ.  (the last one can be set using a trimmer)

Also electrical safety at hobbyist level is less of an issue, since a normal power adapter has been used.  I use a 36V 3A (108 Watt) net adapter to power all.

Apart from the XT60 male plug, and some glue for the Bluetooth module, no other mounting materials are needed. Just the basic tools like a drill, knife and other tools needed to make a hole in plastics.  (and maybe a little soldering)

Shopping list:

And some extra’s like:

So this has become a very small and versatile power supply to fit any desk and can even be wall-mounted or anywhere a DIN rail can be mounted.

Power supply mounted to desk

Prepare LM2596 board

The linked LM2596 board almost fits inside the linked DIN rail enclosure. Only two very small cuts should be made on both sides. Just make sure these are tight enough, since these two cuts also lock the board fixed so no screws are needed.

The IKEA clip will hold the board fixated to the bottom of the DIN rail enclosure.

As can be seen, the board fits really nice in the bottom of the enclosure.

IKEA sealing clip

The cutouts will keep the board positioned when inserting one of those green plugs on the bottom board.
But the board still needs to be pushed down to keep it fixed. (and we don’t want to use screws)

The clip has exactly the right width

The clip has the right width to push down the board using the wider part of the DIN enclosure.
It only needs a little modification to fit the same clip holding the top of the enclosure.
Also a little piece must be removed to make room for a few SMD components on the LM2596 board.

Modified IKEA clip.
IKEA clip in position

Preparing top part enclosure

This is the simple part to explain, and since the DPS module fits so well, it really isn’t hard to make it fit.
If I would make a second one, I would leave a bit more room between the banana plug terminal and the DPS.
Note you can also decide to place the banana plugs on the right of the DPS if you’re left-handed.

Used a label to mark dril positions

The orientation of the DPS and the bottom board must remain the same, or else components of both boards may touch each other. It just fits like this.
I made a small drawing and printed it to a label to help finding the right drill positions for the banana plugs.

I have tried to use 2.5 mm plugs to keep using the existing connector on the power adapter.
But I could not get a proper connection, so I chose a XT60 connector.
These connectors are common on accu packs used in drones and RC planes and are known to handle high currents and provide a good and solid contact.
The power adapter I use provides up to 3A (at 36V), so that really isn’t a lot of current, but there is no such thing as over engineering, as long as it fits 🙂

XT60 E-M chassis detail
XT60 adapter connector inserted

The DPS module fits very well in the top of the DIN rail enclosure.

DPS module mounted in the top of the enclosure

Wiring all together

The wiring is not really rocket science.
The only thing you have to take into account is that the bottom board must be connected using flexible wires.
Using thicker wires makes it almost impossible to close the DIN enclosure and puts mechanical stress on the connectors.
The 36V line will not handle more than 3 Ampere, so the flexible wires I used are thick enough. I used old computer extension cables used to power CDrom drives.
The cables to the banana plug are perhaps a bit too thick, since I used 1.5 mm^2 speaker cable for these connectors, but they may have to deal with up-to 5A, so that’s enough excuse to use thicker cables. 🙂

See also this wire gauges table to get an idea of the maximum current a cable can handle. The computer cables I used are about AWG20, but I am not sure if they are copper stranded.

Wiring inside overview
Wiring inside detail, note the shrink tubes used at all solder joints.

Mounting Bluetooth module

The bluetooth module has some soldering pins at the bottom, which makes it hard to find a position to glue the board to the enclosure.
At the bottom, there is a slide for mounting the enclosure to a DIN rail. I positioned the solder pins right in that slide which makes it very easy to glue the board flat to the bottom of the enclosure. This also provides easy access to the cable, when needed. (the 4 colorful wires in the image below)

Bluetooth module glued to bottom of enclosure (blue PCB)

Document all

I have a Dymo label printer and I once bought these yellow labels with are plastic and thus water proof.
I never used them before, so this is my first attempt to use them.

After some test prints, I decided to invert the prints, which gives a nice look to it, since the enclosure itself is black.
The photos don’t do justice to the effect, since the color looks more dark in reality.

Downloads:

Label specs power supply

Remote controlled power supply

DPS Android app in action

These DPS modules have the option to connect a mobile or PC via either Bluetooth or USB (serial).
This means you can monitor the voltage and current, but also change the set values.
You can also see the history and browse through it, or even export it.

It would be great if this protocol is open, so we can write our own applications for it.

Downloads and links

Downloads:

Shopping list:

And some extra’s like:

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