Duh...
- posted
9 years ago
Duh...
prizes of no interest
NT
I failed. Looks ok to me.
The rectifier diodes are incorrectly drawn
Owen
Try again..
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The non-polarised capacitors are drawn with curved lower plates.
The polarised capacitor on the output isn't usual or helpful, but probably won't blow up an LM7805 if the input were shorted, though it could blow up other three-terminal regulators.
The fact that the transformer hasn't got a turns ratio, the fuse hasn't got a current rating and the AC source voltage is undefined probably wouldn't strike the editorial staff as errors.
-- Bill Sloman, Sydney
Value of C1?
piglet
c1 seems small, not sure what c3 is for.
I don't like that the fuse is after the switch, but again, not likely to be considered an error.
I thought the caps were not drawn right, but seems like a real nit. They put a plus on the two polarized units, so I don't see how it matters really.
-- Rick
Yes, very.
So they are - I even made a point of checking that. I'd better remove myself from the next design review!
Nup, they look ok.
I thought so too.
Yep
bingo :) 10uF for 0.1A isn't going to get far. The other criticisms are more about drawing standards, which many don't follow anyway
NT
I don't see anything wrong. What's your answer?
George H.
C3 and C4 should be swapped to indicate that the 100nF should be closest to the LM7805? Personally, I'd draw the 100nF caps connecting to the regulator vertical GND connection directly, rather than down to the horizontal GND.
But I doubt that's it.
As someone said, C1 is a bit small, but we don't know the current requirements or the input voltage. No voltage ratings on the caps, either, and the 100nF caps aren't polar as shown.
Cheers
-- Syd
The only problem I see is that the schematic does not show which transformer winding is the primary and which is the secondary. But not a real problem.
C3 is probably not necessary, but hardly a mistake. A schematic shows how the person wanted it made or how it was made.
C2 and C4 could be drawn with both plates shown as straight, but can one plate being curved mean that the designer wanted the outer foil connected to ground. You really need the BOM to know if they are polarized or not. I would consider that as being too subtle and there should be a note if is desired for a capacitor to be installed with a certain orientation.
Dan
It's some wise-ass thing like showing the same number of turns on the primary and secondary, i.e. that it's a 1:1 isolation transformer and the overvoltage will blow up the 7805. Pain in the tuchis, really.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant
Are we looking at the same picture? Mine has two cathodes to the positive output, two anodes to the negative, which is correct in my universe. Current goes in the direction of the arrows!
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant
Hint: That which is most obviously correct, beyond any need of checking, is usually the problem.
The fuse and the on/off switch are in the wrong order. The fuse should be first so that if either terminal of the switch is shorted to the other side of the AC power line, the fuse will blow.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com
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