Cordless Mouse & Windows Vista

[Xavier_Onassis]

Well, you'll have to explain about the flashlight one, because in principle it should work, and in actuality it works fine on all of my flashlights around the house (I just tested 'em, they all work with the batteries reversed).

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You have some unusual flashlights. None of mine will do this. I suspect you are making up trying this out.

Put the batteries in your TV remote upside down, or your MR3 player, or any portable radio.

[Amianthus]

You have some unusual flashlights. None of mine will do this. I suspect you are making up trying this out.

Gee, how did I know you were gonna say this? I even recorded myself doing it with one of my "el cheapo" flashlights, just to prove I did it for you. Youtube video - pardon the graininess, I just used the webcam on my computer.

Put the batteries in your TV remote upside down, or your MR3 player, or any portable radio.

Well, that's a completely different situation. None of those are only incandescent bulbs and switches. Those all have devices in them that require specific polarity (the chips).

Hey, you were the one that came up with the suggestion, and then never explained it. Why does a flashlight not work if you reverse the batteries? Are you not going to explain yourself?

(BTW, I can explain why *some* flashlights might not work if you do this, but it's really a design flaw.)

[Xavier_Onassis]

Hey, you were the one that came up with the suggestion, and then never explained it. Why does a flashlight not work if you reverse the batteries? Are you not going to explain yourself?

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It was your contention that no one should use a device that they did not understand.

It is my contention that if this were indeed true, almost no one would use any device.

Look, if you just take a couple of wires, a battery and a bulb, you will see that the bottom of the bulb must be connected to the  + or the top nipple-thing of the battery and the side of the bulb must be connected to the - terminal of the battery (that is the bottom of the battery) for the bulb to produce light.

Flashlights work in the same exact way, and I suspect for the same reason, but they use the sides of the flashlight rather than wires and have a simple switch.

 Your car won't start if you connect the battery backwards, but don't try this, as you will fry the computer of any modern car. It wasn't good for cars back in the days of 6-volt systems and generators, either, but it is a lot worse on alternator syates, as it destroyed the diode in the alternator as a rule.

The bulb will not be damaged of you use the wrong polarity, but it will not glow at all.

Why is this? I am not sure, but it is a fact, and we all use flashlights and I have never heard anyone explain why this is so. Which, I think proves my point: namely that we all use devices without a complete knowledge of why they work.

Electrical engineers I have known, when asked this question have generally given the following answer: "I am not a hardware man", an answer I consider to be unsatisfactory.

I continue to believe that you did not try reversing any batteries in any of your flashlights. Had you done so, you would not be saying that only defectively designed ones fail to work with the batteries reversed.

[Amianthus]

Look, if you just take a couple of wires, a battery and a bulb, you will see that the bottom of the bulb must be connected to the  + or the top nipple-thing of the battery and the side of the bulb must be connected to the - terminal of the battery (that is the bottom of the battery) for the bulb to produce light.

Actually, that's not true. An incandescent bulb has no polarity, you can connect either terminal to positive, and the other to negative, and it will glow. That's why they work with AC, which has a reversing polarity.

Perhaps you SHOULDN'T be using a flashlight?

I continue to believe that you did not try reversing any batteries in any of your flashlights. Had you done so, you would not be saying that only defectively designed ones fail to work with the batteries reversed.

Did you watch the video of me doing it?

[Amianthus]

Did you watch the video of me doing it?

And another video, this one with sound -> http://www.youtube.com/watch?v=lIoGAXolNE0

[Amianthus]

And, from a electrical primer:

For many purposes polarity is unimportant. Conventional light bulbs, for example, work by the heat generated when electricity is passed through a resistance and as such the direction of current flow is irrelevant.

There are other items however where the polarity matters. Some electric motors, for example, will turn in the wrong direction if the supply is reversed.

[hnumpah]

Look, if you just take a couple of wires, a battery and a bulb, you will see that the bottom of the bulb must be connected to the  + or the top nipple-thing of the battery and the side of the bulb must be connected to the - terminal of the battery (that is the bottom of the battery) for the bulb to produce light.

That is not necessarily true - it is just the easiest way to provide a positive and negative terminal for use in the flashlight. The bulb itself, if it is a plain incandescent bulb, could care less which way you connect it, and will work either way. An LED (light emitting diode -  see below) will not, as they must have the polarity correct; also, the small xenon bulbs used in Maglites may be polarity sensitive (I don't remember, and I'm too lazy to pull my Maglite apart to check it - I do know the bulb you are supposed to use in the flashlight is supposed to correespond to the number of cells [batteries] used in the flashlight). But a regular, incandescent bulb will work both ways.

Your car won't start if you connect the battery backwards, but don't try this, as you will fry the computer of any modern car. It wasn't good for cars back in the days of 6-volt systems and generators, either, but it is a lot worse on alternator syates, as it destroyed the diode in the alternator as a rule.

That is because diodes and computer chips are polarity sensitive devices. They are supposed to only work one way.

The bulb will not be damaged of you use the wrong polarity, but it will not glow at all.

Why is this? I am not sure, but it is a fact, and we all use flashlights and I have never heard anyone explain why this is so. Which, I think proves my point: namely that we all use devices without a complete knowledge of why they work.

Wrong. See above.

Electrical engineers I have known, when asked this question have generally given the following answer: "I am not a hardware man", an answer I consider to be unsatisfactory.

Then they are either not electrical engineers, or they are the stupidest electrical engineers in the world.

I continue to believe that you did not try reversing any batteries in any of your flashlights. Had you done so, you would not be saying that only defectively designed ones fail to work with the batteries reversed.

Ami was right. I spent over 25 years working in electronics. If you're still having trouble getting it to work, you may be defective.

[hnumpah]

By the way, you can't normally get the batteries to work backwards inside a normal flashlight - the raised tip on the + side of the battery fits into a cup on the base of the reflector assembly, so if you try to put the flat base of the battery (the - side) against it, the raised edges of the cup will keep the battery from making contact.

[Amianthus]

also, the small xenon bulbs used in Maglites may be polarity sensitive

No, they're not.

[Amianthus]

By the way, you can't normally get the batteries to work backwards inside a normal flashlight - the raised tip on the + side of the battery fits into a cup on the base of the reflector assembly, so if you try to put the flat base of the battery (the - side) against it, the raised edges of the cup will keep the battery from making contact.

Some flashlights are designed this way, but many more are not - they will either just use the base of the bulb as the contact (which is a little nub) or the contact area at the bottom of the reflector is just flat.

I've pulled many batteries out of flashlights over the years where the nub at the top was dented in by the nub at the base of the bulb, when the battery was in the flashlight for an extended period of time.

[Xavier_Onassis]

By incandescent bulb, I mean the sort of DC bulb one finds in a flashlight, not an AC bulb in a 110 V lamp. AC current will work either way, but DC won't.

Alas, I am at the Univ., and I cannot access YouTube here. I shall have to go home before I can watch your amazing demo.

I know that LED's will not work with reversed polarity, but again, I do not know why this is. I still, however, feel eminently qualified to continue to use my LED flashlights with impunity.


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Your car won't start if you connect the battery backwards, but don't try this, as you will fry the computer of any modern car. It wasn't good for cars back in the days of 6-volt systems and generators, either, but it is a lot worse on alternator syates, as it destroyed the diode in the alternator as a rule.

That is because diodes and computer chips are polarity sensitive devices. They are supposed to only work one way.

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In agree that this is true with modern cars. But my 1951 Chevy Master Deluxe had nary a diode nor a computer chip nor even a transitor in it, and would not start with the battery in backwards. As I recall, when I purchased a new battery once, the yokel at the station stuck the battery in wrong, and all that was produced was the smell of burning insulation, which continued until the battery was turned around the right way.\
This car had a generator, not an alternator.

A logical mind might have assumed that this would have caused the starter to turn backwards, and yet nothing like this occurred. I have no ancient vehicles upon which to repeat this lame experiment.

Again, my original contention is that most people use equipment every day that they do not understand.

If one were to interview all 600 passengers of a huge airbus, I wager that not one would be likely to explain how it was that this heavy thing could possibly fly. I would think that the Pilot wand Copilot and Navigator might have a clue as to how an airfoil works, though.

[Amianthus]

By incandescent bulb, I mean the sort of DC bulb one finds in a flashlight, not an AC bulb in a 110 V lamp. AC current will work either way, but DC won't.

Incandescent bulbs will work with either AC or DC. You just gotta match up the voltage and current correctly. Notice that Christmas tree bulbs sold will work on either the regular AC type string, or the fancier strings that flash the lights in varying patterns that run on DC or batteries. Same bulb, works with both AC and DC. Because, polarity does not matter with incandescent light bulbs.

I know that LED's will not work with reversed polarity, but again, I do not know why this is. I still, however, feel eminently qualified to continue to use my LED flashlights with impunity.

Because they're "light emitting DIODES" and as a solid state circuit, they are polarity dependent.

[Amianthus]

If one were to interview all 600 passengers of a huge airbus, I wager that not one would be likely to explain how it was that this heavy thing could possibly fly. I would think that the Pilot wand Copilot and Navigator might have a clue as to how an airfoil works, though.

I'll take that bet. You do the interviews.

I'm not like you, who thinks that nearly everyone is much dumber than he is.

[kimba1]

I got a better one ask people at work how much music a blank cd can hold.
megabytes as I explained before is not easy to teach.

[hnumpah]

...my 1951 Chevy Master Deluxe had nary a diode nor a computer chip nor even a transitor in it, and would not start with the battery in backwards. As I recall, when I purchased a new battery once, the yokel at the station stuck the battery in wrong, and all that was produced was the smell of burning insulation, which continued until the battery was turned around the right way.\
This car had a generator, not an alternator.

A logical mind might have assumed that this would have caused the starter to turn backwards, and yet nothing like this occurred. I have no ancient vehicles upon which to repeat this lame experiment.

The starter wouldn't need diodes, transistors or computer chips. They are simple electric motors. Put the juice to 'em, they turn. The starter is either wired to only go one way, or mechanically prevented from running backwards. That was probably the case with your old starter motor, because the engine it was supposed to turn would only start, and run, one way. If you connected the battery backwards, the current would be running through the motor, which was prevented from turning backwards; eventually it would get hot and, if left long enough, burn up the motor.

Once the engine was started and you let the key return to the 'run' position, the starter motor would shut off because it was no longer needed. Then the generator would take over to generate the power needed to run the lights, radio, etc., as well as provide power to the points and plugs to run the motor. It also provided AC power that was converted to DC, the voltage regulated back to about 12 volts DC, and used to recharge the battery. The conversion back to DC is where the diodes come in. They are used in bridge rectifiers, to convert AC to DC. Diodes, or rectifiers, have been around since before the turn of the century, so I'm not certain you could be so sure your old '51 DeSoto, or Edsel, or Studebaker, or whatever, didn't have one, or two, or several.