Amateur radio and embedded systems

What is inside a Mean Well DIN rail power supply

I bought a small power supply in DIN rail form factor to provide 12V for the Waveshare RS485 to Ethernet converter mounted in my breaker panel. The exact model is HDR-15-12.

Installation is trivial as it only has 2 screw terminals for the AC input and 2 for the DC output (it is better to not get them mixed up). The outside looks fairly standard. Front has a single blue LED (that is of course too bright), adjustment pot and the screw terminals. Voltage shown by my cheap multimeter was an exact 12.00 V so I did not have to do any adjustments. The PSU works well with the Waveshare converter and does not squeak or emit any audible noise (at least from what I can hear...).

Power supply front view

Let's see what is inside...

Insides look like a classical, isolated, switched-mode power supply with an optocoupler in the feedback path. The overall quality is okay. The high and low voltage sides of the PCB are separated by a slot (air gap).

The PSU on the pictures is flipped. To find out which side is the input (AC) and which is the output (DC) you can look where the pot and the LED is. That is the output DC side.

Power supply PCB top view

Power supply PCB bottom view

Power supply side view