Ken Shirriff performs another thorough teardown and reverse engineering, this time on a computer power supply.
Have you ever wondered what’s inside your computer’s power supply? The task of a PC power supply is to convert the power from the wall (120 or 240 volts AC) into stable power at the DC voltages that the computer requires. The power supply must be compact and low-cost while transforming the power efficiently and safely.
The power supply I examined, like most modern power supplies uses a design known as a “switching power supply.” Switching power supplies are now very cheap, but this wasn’t always the case. In the 1950s, switching power supplies were complex and expensive, used in aerospace and satellite applications that needed small, lightweight power supplies. By the early 1970s, though, new high-voltage transistors and other technology improvements made switching power supplies much cheaper and they became widely used in computers.
An ATX power supply is complex internally, with a multitude of components ranging from chunky inductors and capacitors to tiny surface-mount devices. This complexity, however, results in power supplies that are efficient, lightweight, and safe. In comparison, I wrote about a power supply from the 1940s that produced just 85 Watts DC, but was suitcase-sized and weighed over 100 pounds. Now, with advanced semiconductors, you can hold a much more powerful power supply for under $50 that you can hold in your hand.
I’ve written about power supplies before, including a history of power supplies in IEEE Spectrum. You might also like my Macbook charger teardown and iPhone charger teardown.
Read about all the details in Ken’s blog post here.