In this video we go through every component of a modern switch mode power supply taking a look at their function. The first half of the video is dedicated to understanding how inductors are used in these circuits, as these are the beating hearts of power supplies. The second half of the video runs through each component, with increasing complexity, highlighting their position in both the schematic and the physical circuit before delving into their purpose.

What happens when:
0:00 Introduction
0:31 Evolution of switch mode power supplies (1980-2022)
1:47 Using inductors to store and release energy
3:40 Using inductors in a switch mode power supply
9:47 How inductors keep shrinking
11:35 Introduction to circuit analysis
12:00 Simplest possible SMPS
14:31 Output indicator LED
14:49 Additional output filtering
15:19 Output capacitor bleeder resistors
16:01 MOSFET source current shunt resistors
16:37 Input filtering
17:52 Input protection
19:54 Class-Y capacitors
20:35 Snubbers
21:47 Additional components (controller)
22:06 Conclusion
22:40 Outro

I am building a bench power supply. So today I bought two 24V / 10A power supplies. A 36V or 48V power supply is twice as expensive as a 24V power supply . So I bought the 24 power supply and modified it to 36V. The modification is very simple, you just need to replace feedback resistor (in my power supply. it is 2K, I replace it to 1K). Next you need to replace the 35V filter capacitors to 50V or 63V. For a 12V power supply, do the same.

It should be pointed out that you will be dropping your current capability by at least half doing this. So you will need a power supply that will be at least double what you need in your final application.

If you bought a 12V 10A supply, it is capable of 120 watts. If you modify it to 24V, it would be 5A max because the power supply is still only capable of 120 watts.

Apart from the fan which was not designed for 36v, you should check the dissipation rating of the two resistors in the potential divider you changed – lowering the resistor value will increase the current flowing and the top resistor will also see the increased output voltage.

Very informative. You are pretty careless with your handling with mains connected. Those terminals ar
not reliable and you didn’t test the integrity with even a small ‘pull’ after connection. a mains wire slipping out
can do damage to the case or to you …depending on the situation.

First – cleaning.
Second – recap.
Third – diodes.
Fourth – the output transformer.
And then … imagine.

Very easy to check it if you have the tools. A variable PSU with current limit can be used to power it up, by apply 24V 1A directly connect it to the 400V caps lead. Make sure polarity is right or you will further damage more components on the board. Bypass the Vcc pin of pwm contoller ic with a 100 ohm resistor to the positive supply of 24 V. Check the output gate driver. Also check the MOSFET. That’s one of the culprit in failed smps. PTC and the rectifier diodes at the primary side also need to be checked. Any bulging caps need to be replaced with the same specs. Don’t forget check the fuse.