Electrical Engineering Challenge

Duh...

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prizes of no interest

NT

Reply to
meow2222

I failed. Looks ok to me.

Reply to
McAvity

The rectifier diodes are incorrectly drawn

Owen

Reply to
Owen Cook

Try again..

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Reply to
bitrex

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.

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Bill Sloman, Sydney
Reply to
Bill Sloman

Value of C1?

piglet

Reply to
piglet

c1 seems small, not sure what c3 is for.

Reply to
Cydrome Leader

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.

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Rick
Reply to
rickman

Yes, very.

Reply to
Robert Baer

So they are - I even made a point of checking that. I'd better remove myself from the next design review!

Reply to
McAvity

Nup, they look ok.

Reply to
McAvity

I thought so too.

Yep

Reply to
McAvity

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

Reply to
meow2222

I don't see anything wrong. What's your answer?

George H.

Reply to
George Herold

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

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Syd
Reply to
Syd Rumpo

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

Reply to
dcaster

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

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Dr Philip C D Hobbs 
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Reply to
Phil Hobbs

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

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Reply to
Phil Hobbs

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.

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Jeff Liebermann     jeffl@cruzio.com 
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Jeff Liebermann

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