They did have sinks on them, that were cylindrical - the sinks went around the board, inside the plastic casing (can't really explain it - wish I had taken photos now!).Rhinoman wrote: 4W is a lot for a 7805 without a heatsink, that would be a junction temperature of around 290C - except it would smoke in less than a second. Did they have a current rating on them?
Cheap Chinese stuff isn't necessarily bad, a lot of good stuff comes from there too. Whats inside the 3.5A jobbie?
They got very hot, but not 290c. I'd guess at about 50c - they were hot enough that you wouldn't want to touch one when it was in use. I did burn myself on one a little when taking it out of the ciggy socket after it died.
Can't tell you much about them, I couldn't actually read "7805" on them after they toasted. The only reason I was (fairly) sure they were 7805's was because I had 2 of them, and after toasting both (first one got tossed in the glove compartment after toasting the first one) I pulled them apart to see what was inside. I could read the 7 on the first one, the 5 on the second one. More or less.
So I could be wrong, but they *seemed* like 7805's to me.
I'm not entirely sure what's inside the 3.5A jobbie - http://www.ebay.co.uk/itm/251009862646
Oh, and it's 3A, not 3.5 - my bad.
