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help with the mini^3

post #1 of 62
6/19/08 at 7:17pm
Thread Starter 
Hi, I've hit some delays in the process of building my mini^3. Firstly, I made the embarrassing mistake of forgetting to order the right quantity for one of the parts. I order only one instead of three 1N4001 1A rectifier DO-41, so D2 and D3 are empty. Will the amp work without them?

Also, I'm going to solder the LEDs, but I can't figure out the orientation it should be. I know the longer lead is the positive end, but which hole does the positive lead fit through on the board?

Link to the diagram
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post #2 of 62
6/19/08 at 7:23pm
The flat side marked on the silkscreen (and you'll see that the LED package has a flat side as well) is the cathode or negative side. You can use the flat side to identify the polarity once the leads have been clipped. So to answer your question, the positive lead goes in the hole opposite the flat side of the diagram.

Which part are you missing?
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post #3 of 62
6/19/08 at 7:42pm
Thread Starter 
I am missing two 1N4001 1A rectifier DO-41. I accidentally only ordered one, so D2 and D3 are empty right now.
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post #4 of 62
6/19/08 at 8:01pm
Quote:
Originally Posted by kilgoretrout View Post
I am missing two 1N4001 1A rectifier DO-41. I accidentally only ordered one, so D2 and D3 are empty right now.
PM me your address, I'll drop some in the mail tomorrow.
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post #5 of 62
6/19/08 at 8:01pm
Those are part of the diode OR gate of the charging circuit. It appears that the amp would work on battery with D3 populated. Even Ratshack has these... any of the 1N400x diodes will work (1N4003 is common).
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post #6 of 62
6/19/08 at 8:45pm
Thread Starter 
Quote:
Originally Posted by error401 View Post
The flat side marked on the silkscreen (and you'll see that the LED package has a flat side as well) is the cathode or negative side. You can use the flat side to identify the polarity once the leads have been clipped. So to answer your question, the positive lead goes in the hole opposite the flat side of the diagram.

Which part are you missing?
I can't tell what side is flat on the LED. What exactly am I looking for?
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post #7 of 62
6/19/08 at 9:40pm
Standard LEDs have a mounting flange along the lower edge of their bodies. You'll find that one side of the flange is flattened, while the rest of the LED follows the circular contour. You end up with the flange having a 'D' like shape, with the flat side being the cathode. It's pretty hard to see on 3mm LEDs at times. You can see the identification methods in this picture from wikipedia:


If you've already found the long leg though, you don't need to worry about the flat side, I was just trying to give you extra information for the future. You can trust that the long leg is positive.

And as everyone else says, 1N400x are available everywhere, they're the ubiquitous general purpose rectifier diode. Probably one of the most available semiconductor components there are (alongside 2N3904, 1N4148, etc.). You should be able to find them at any electronics shop. FallenAngel beat me to it, but if you need a few drop me a line and I'll send you some in the mail.
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post #8 of 62
6/19/08 at 10:41pm
Thread Starter 
I gave my LEDs a good look, and I'm sure that it has no flat side as shown in your diagram. No worries though, I installed it based on the long leg.

On another note, while I was soldering U4 (OPA690ID), I positioned it incorrectly at first. I managed to get it off the board. Then, I replaced it with the correct positioning. Should I be worried of damage to the chip? Is there any way to test it?
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post #9 of 62
6/19/08 at 11:33pm
If you didn't apply power with it in backwards it should be fine if there's no physical damage. If power was applied, chances are good that it's dead, but you can't hurt it by trying with it set up properly.
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post #10 of 62
6/19/08 at 11:58pm
Use a battery (9V is easiest). Grab a big resistor, 10K+ for example, and connect the leads to the battery in series with the resistor. I normally put the resistor on the + terminal, connect the led to the resistor and plug the other end of the LED into the - terminal. I use whatever I have, tape, clips, twist together, etc. to hold the LED and resistor together. The order in which it lights will tell you which terminal is which.

There are some LEDs which have the reverse leg lengths, for example. I've been burned by that before. If you can't find the datasheet for the LED, use the battery method.
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post #11 of 62
6/20/08 at 9:24am
Thread Starter 
Quote:
Originally Posted by error401 View Post
If you didn't apply power with it in backwards it should be fine if there's no physical damage. If power was applied, chances are good that it's dead, but you can't hurt it by trying with it set up properly.
I did not apply power with it in backwards, but I am still concerned about having it heated for too long. This will not cause a problem?
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post #12 of 62
6/20/08 at 9:28am
Thread Starter 
Quote:
Originally Posted by holland View Post
Use a battery (9V is easiest). Grab a big resistor, 10K+ for example, and connect the leads to the battery in series with the resistor. I normally put the resistor on the + terminal, connect the led to the resistor and plug the other end of the LED into the - terminal. I use whatever I have, tape, clips, twist together, etc. to hold the LED and resistor together. The order in which it lights will tell you which terminal is which.

There are some LEDs which have the reverse leg lengths, for example. I've been burned by that before. If you can't find the datasheet for the LED, use the battery method.
The date sheet is here:
http://www.us.kingbright.com/images/...C/WP7104GD.pdf

It can't find anything that indicates the polarity clearly.
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post #13 of 62
6/20/08 at 1:25pm
Actually it does, FWIW. It marks the cathode (-) as the short leg. That makes the anode (+) the long leg.

If you're not sure double check with the battery method.
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post #14 of 62
6/21/08 at 4:14pm
Thread Starter 
Hi, I have another question. Can I use a non-rechargeable alkaline battery to do the initial tests? The reason I ask is because the rechargeable batteries are uncharged out of the box, and I do not have a separate charger. They will only be used briefly for the tests.
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post #15 of 62
6/21/08 at 4:16pm
yes, just don't plug in the wallwart. Use the rechargeable to test the charging circuit, in accordance with AMB's notes.
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