To avoid switching noise near the work bench, I wanted to drive my LED strips from a plain ol’ transformer -> bridge -> capacitor supply. It would have to supply about 2A @ 12V for my LEDs. Here’s the setup:
Ignore the diodes at the top, these were 1N4004 diodes which weren’t quite up to the task. The ones at the bottom right are Schottky diodes for a lower voltage drop, rated at 5A. The capacitor is 2200 µF, but ripple isn’t an issue.
Alas, the heat from this thing is excessive. I even went for an artsy swiss-cheese design:
Trouble is the transformer (and surprisingly not the diodes!) – I measured them both, with everything closed:
Diodes heated up to 75°C – but the transformer went all the way up to well over 90°C within the hour! AC mains consumption is 50W, so this silly thing is eating up half the power while trying to behave like a stove…
The transformer is a cheap 2x6V @ 2.5A unit I had lying around (draws 3.7W, even without any load). I’ll keep this as a high-ripple 12..20 VDC power brick for testing - but it definitely can’t be used continuously @ 2 Amps!
PS. If you’d like to meet up – I’ll be presenting JeeStuff at HackersNL coming Thursday evening in Utrecht.