Comment by Stephen Upham — January 5, 2012 @ 1:02 pm
Wow… That inductor thing was a first for me. Someone evidently didn’t understand the difference between a schematic and board layout, if anything, they’ve created more of a resistor than an inductor. “There is only one diode, probably salvaged from an old WWII Panzer IV tank” I wouldn’t have even bothered to fix the power supply, at that point, Widlarizing the entire supply is probably a better option.
I suspect the missing inductors on the input side are for PFC, and since PFC isn’t legally required everywhere, cheap shit power supplies omit PFC components when they’re sold in places that don’t require it. (But PFC isn’t very important for a camera power supply, is it?)
Great piece, but more than anything I appreciate Giorgos as “one of us.” Not content to just accept the problems he saw, he dug into the issue, explained it well and then did something about it. We need more of this spirit and it is a great cautionary tale.
@Harry: I guess he just couldn’t resist a challenge.
@Kragen: Possibly. In that case I guess you would cut those “inductive traces”?
@jorge: from the outside it really does look like a genuine Canon supply, though. I have a real one and I compared it to the one in the video — the case, sticker, strain relief and plugs are identical. Perhaps they used a Canon case and put their own guts inside it? Seems like a lot of work to pull off something like that.
@John and Kragen: That would make sense, then: If it doesn’t need PFC, don’t put in the diodes and instead use the traces to conduct. If you do need PFC, insert the diodes, and then you have marked traces so you know exactly which ones to cut, and don’t have to hunt around to figure it out. Even so, yikes. A definite case of “Muntz-ing” on their end.
I have bought several of those power supplies to run my old A450 digital cameras that I use as a ghetto webcam (since they have great macro mode) with the composite out into an ezycap
They work fine, but yeah, not the greatest.
PFC is unnecessary on a supply that small unless you want to get a real CE approval etc, and IMO just leave it out is the best idea, and I have always seen a single diode on the output side of the transformer in a SMPS?
At least this one had a bridge on the input, all the cheap 99c USB wallwarts on there just have a single diode on the input.