I was browsing the thrift store and found a nice pair of JBL 2.0 computer speakers, but they lacked a power adapter. They call for a 12V 1A supply. I have a ton of "bricks" lying around, but no 12V ones to spare (if it's possible and economical to turn a 5V 3A brick into a 12V 1A+, please point me in the right direction). At the store I bought a cheap router that included the one on the left, but it's very light. I envisioned the necessary adapter to be very heavy, as any older computer speakers I've seen had a heavy brick, so I kept looking and found the one on the right sold individually. It's got to weigh 5x as much, but the specs look similar (I understand it's only 700mA and that means I can't draw as much power). If neither is a good fit I'd rather purchase a new one than chance it, but this got me thinking:
What's the difference between these two types of adapters?
Best Answer
A "heavy" power supply contains a 50/60 Hz transformer to provide the necessary isolation between the mains and the DC output. This transformer has a laminated steel core that needs to be fairly massive in order to provide an adequate impedance to the line voltage.
A "light" power supply uses active electronics to convert the line frequency to a much higher frequency (on the order of 20 to 100 kHz). This allows the isolation to be achieved with a much smaller transformer that has a powdered ferrite core.
As long as the output ratings are compatible (same voltage, same or higher current rating), they're mostly interchangeable. Beware of the difference between regulated and unregulated power supplies.