Random Thoughts Part 4 - Split Thread

[WWGD]

I am never sure of what to make when, during a conversation with a woman, she brings up her husband. For now, I just smoothly end the conversation.

 

[zoobyshoe]

I am never sure of what to make when, during a conversation with a woman, she brings up her husband. For now, I just smoothly end the conversation.

It means she wants you and is struggling to remind herself she is married.

 

[WWGD]

It means she wants you and is struggling to remind herself she is married.

I think you would be right if I was a 7 or higher, but I am more of a 5-6, 6.5 on a really good day.

 

[collinsmark]

I have two questions: the brighter lamp has 24 LED's but runs on the same voltage as the 6 LED lamp. Indeed, the 24 LED lamp uses AAA batteries while the 6-LED lamp uses AA batteries. In both cases the LED's are connected in parallel. I don't understand the limits here. What's to prevent me from making a 1000 LED lamp and powering it with three batteries and getting a dazzlingly bright light?

It's difficult for me to say without knowing a bit more about the extra circuitry involved. LEDs are very non-linear, meaning that voltage and current are not directly proportional. The operating voltage of an LED doesn't change much. The range of voltage is quite small from being barely lit to the point where it's so much that the LED burns out. The current on the other hand will change along with the brightness.

(The simplest way to keep the LED's brightness roughly constant over the variation in battery voltage, as it depletes, is by using a current limiting resistor. But that's not very efficient [much of the power in the circuit is wasted by the resistor, due to $I^2R$ power loss]. That's why LED driver circuits are preferable if you've got 'em, because they're more efficient [that and the the more consistent brightness]).

But at the risk of oversimplification, all else being equal, by wiring things in parallel the current draw increases but the voltage does not. Making a few assumptions about your LED modules and circuits, the group of 24 LEDs may run on the same voltage as the group of 6 but will draw 4 times the amount of current, approximately, meaning the battery will only last approximately 1/4 as long.

With 1000 LEDs you'll probably find the internal resistance of the battery rears its head. The terminal voltage of the battery is the battery's emf minus $IR_i$ where $R_i$ is the internal resistance of the battery. With 1000 LEDs the current draw would be enough to drop the terminal voltage of the battery pretty low. Suffice it to say that it wouldn't work very well.

The other question is about rechargeable AAA and AA batteries. Is it OK to recharge them when they are not appreciably depleted? If I get four hours of decent light out of them there still might be 16 hours of worthless glowing that does me no good, so can I safely recharge them when they are down to, say, 1.2 volts per cell?

It's okay to fully* deplete rechargeable battery technologies such as NiMh or NiCd. 'Just keep them going until the lamp stops working. As a matter of fact, that's the best way if you are using NiCd batteries. For those, you should deplete them fully* before recharging. Lithium ion is different in that respect: fully depleting a Li-Ion battery will brick it.

*[Correction: you should not totally, "fully" drain a NiMh or NiCd, as that can permanently damage even those batteries. My original wording was misleading in that respect. What I should have said is "Run your lamp until it stops working well, and then turn it off and recharge the batteries." I didn't mean that you should absolutely drain every last drop of charge out of them. Please forgive my bad wording.]

 

[Silicon Waffle]

It's difficult for me to say without knowing a bit more about the extra circuitry involved. [...]
*[Correction: you should not totally, "fully" drain a NiMh or NiCd, as that can permanently damage even those batteries. My original wording was misleading in that respect. What I should have said is "Run your lamp until it stops working well, and then turn it off and recharge the batteries." I didn't mean that you drain every last drop of charge out of them. Please forgive my bad wording.]

So much detail to be understood.

 

[collinsmark]

So much detail to be understood.

Sorry about that.

It's fine to allow NiMh or NiCd batteries to drain to the point where the device their powering pretty much stops functioning. As a matter of fact that's the best approach for NiCd batteries. But just remember to turn the switch off when that happens. Don't leave them depleted, sitting in the device they are powering, with the device turned on, indefinitely. That's where the trouble starts.

 

[dkotschessaa]

Sorry about that.

It's fine to allow NiMh or NiCd batteries to drain to the point where the device their powering pretty much stops functioning. As a matter of fact that's the best approach for NiCd batteries. But just remember to turn the switch off when that happens. Don't leave them depleted, sitting in the device they are powering, with the device turned on, indefinitely. That's where the trouble starts.

Guys, seriously. This conversation. Even by physics forum standards it's kind of um... well..

 

[collinsmark]

Back to "random" it is then.

Tonight is my trivia team night. The free answer of the day is "sculpture." But they don't tell you what the question is. Hmm. What sort of trivia question has the answer of "sculpture," I wonder.

 

[Silicon Waffle]

Back to "random" it is then.

Tonight is my trivia team night. The free answer of the day is "sculpture." But they don't tell you what the question is. Hmm. What sort of trivia question has the answer of "sculpture," I wonder.

Very easy, you can just ask anyone "what is sculpture ?". All of them know what it means and how to explain it, so if they answer you something meaningful, then they know the answer of "sculpture". The fact is your question is the most trivial one.

 

[zoobyshoe]

Making a few assumptions about your LED modules and circuits, the group of 24 LEDs may run on the same voltage as the group of 6 but will draw 4 times the amount of current, approximately, meaning the battery will only last approximately 1/4 as long.

I should have mentioned that it doesn't seem to be the case with these lamps. My impression is that they both last about the same time. In fact, the 6 LED ones seem to deplete faster than the ones with more LEDs. Also, neither has any "circuitry," not even a resistor.

However, I just remembered something that would account for this, which is pretty stupid, but slipped my mind: I have often found the dollar store lamps get turned on by being jostled around in my backpack. The on button is easily depressed, and I keep them in a pocket with a bunch of other stuff. More likely than not, I have underestimated how long they've been on in there, preferring to suppose I caught it right after they got turned on.

 

[zoobyshoe]

Back to "random" it is then.

Tonight is my trivia team night. The free answer of the day is "sculpture." But they don't tell you what the question is. Hmm. What sort of trivia question has the answer of "sculpture," I wonder.

Which medium did Michelangelo prefer: painting or sculpture?

 

[zoobyshoe]

Ever since the first episode I've been wondering what happened to that flying saucer.

 

[WWGD]

Back to "random" it is then.

Tonight is my trivia team night. The free answer of the day is "sculpture." But they don't tell you what the question is. Hmm. What sort of trivia question has the answer of "sculpture," I wonder.

"What is the free answer of the day"?

 

[Ibix]

Tonight is my trivia team night. The free answer of the day is "sculpture." But they don't tell you what the question is. Hmm. What sort of trivia question has the answer of "sculpture," I wonder.

"How would a surrealist answer this question?"

 

[dkotschessaa]

Back to "random" it is then.

Tonight is my trivia team night. The free answer of the day is "sculpture." But they don't tell you what the question is. Hmm. What sort of trivia question has the answer of "sculpture," I wonder.

In what form will my romanesque physique be preserved for future generations to ogle?

 

[Ibix]

A mate of mine does MMA. He was telling me about some "gecko-roman" wrestling that had happened in a bout. That gave me a very odd mental image until I figured out that he meant greco-roman.

 

[dkotschessaa]

A mate of mine does MMA. He was telling me about some "gecko-roman" wrestling that had happened in a bout. That gave me a very odd mental image until I figured out that he meant greco-roman.

There's lots of geckos roamin' here in Tampa.

In fact I caught a couple of them um..wrestling...
(NSFW if you are a gecko)

 

[WWGD]

A mate of mine does MMA. He was telling me about some "gecko-roman" wrestling that had happened in a bout. That gave me a very odd mental image until I figured out that he meant greco-roman.

I think your mate will be needing health insurance instead, hopefully not too much of it.

 

[WWGD]

When I hear people saying " I would not wish this on my worse enemies", I think these people have some pretty lame enemies.

Second time in few days I have accidentally sent a text to the wrong person. I will think twice
before texting " I love you" and others until I am more focused.

 

[fresh_42]

When I hear people saying " I would not wish this on my worse enemies", I think these people have some pretty lame enemies.

Second time in few days I have accidentally sent a text to the wrong person. I will think twice
before texting " I love you" and others until I am more focused.

Consider it from a Buddhist point of view: spreading love can never be wrong!

 

[OmCheeto]

There's lots of geckos roamin' here in Tampa.

In fact I caught a couple of them um..wrestling...
(NSFW if you are a gecko)

Oh! You've preemptively answered my next question; "Do you still live in Florida"?

I was going to offer to fly down and be your wife's personal manservant, as some kid in Nova Scotia claims that everyone one here is in dire straits.

​

It's nice to know that at least one Canadian is worried about us.

ps. Nova Scotia is 3000 miles away.
pps. That kid nailed it! I had record setting mud puddles all around my house yesterday. And a wind gust blew over my recycle bin! Oh, the humanity...

 

[PWiz]

These college applications are killing me

Maybe I can slip in some of my stormy night adventures at the physicsforums inn into those 40+ supplement essays

 

[fresh_42]

It's nice to know that at least one Canadian is worried about us.

I have a friend grown up in NM and she doesn't get tired saying Canadians are the better Americans

 

[dkotschessaa]

It's nice to know that at least one Canadian is worried about us.​

ps. Nova Scotia is 3000 miles away.
pps. That kid nailed it! I had record setting mud puddles all around my house yesterday. And a wind gust blew over my recycle bin! Oh, the humanity...

He has a future in 90s speed metal.

I suggest first playing this video in the background:


Then play:

 

[JorisL]

I chuckled at that.

 

[OmCheeto]

He has a future in 90s speed metal.

Having just yesterday, finished marathon watching all 413 Dr. Who episodes offered by Hulu, I think this is doable.

I suggest first playing this video in the background:


Then play:

Frankie's presentation was much less painful, than that of 90s speed metal, IMHO.

But I think this young gentleman has a future roll as a Dalek voiceover; "Emergency! Emergency! Have your cellphones charged! Have your laptops charged! ..."

​

ps. I had never heard of Frankie before the day before yesterday. I really like him. Apparently, he is an international weather reporter.
pps. He also inspires me, to inform people. For instance, does anyone else put their celery bunches from the store in a mug with water at the bottom? I've noticed that if I leave celery out, it drys up before I can eat it all. If I put it in the fridge, it doesn't fare much better. But if I put it in a mug, with water, it lasts for weeks. It even grows!

 

[fresh_42]

But if I put it in a mug, with water, it lasts for weeks. It even grows!

And if you clean your red radish before you put it with a paper towel in a tupperware box into the fridge, it won't fade either. (Just saying.)

 

[OmCheeto]

And if you clean your red radish before you put it with a paper towel in a tupperware box into the fridge, it won't fade either. (Just saying.)

I don't know that I've ever bought a radish, so, um, I don't care. SORRY!

But I did loogle "celery", and found a PF Christmas Chat from 2008. What a hoot!
Someone mentioned; [] 7:10 pm: i want some pimento cheese on celery sticks

I only like peanut butter on my celery sticks.
I also have never heard of "pimento cheese".
Must have been an east coast PFer.

 

[fresh_42]

Small or red radish. Those tiny red balls you can eat like mixed pickle or as a snack.

I only like peanut butter on my celery sticks.
I also have never heard of "pimento cheese".
Must have been an east coast PFer.

I'am always on the search what can be eaten to peanut butter beside jelly and Satay. I even tried the rumor about Elvis' favor for banana sandwiches. Honey fits, too. But celery? Wiki locates pimento cheese to the south but I truly doubt that's been a leftover of the French.

 

[dkotschessaa]

Peanut butter and celery combines my love of peanut butter with my love of things that I can put peanut butter on.

 

[Borg]

For instance, does anyone else put their celery bunches from the store in a mug with water at the bottom?

I do that with Romain lettuce but I still keep it in the fridge. The lettuce stays nice and crisp.

 

[OmCheeto]

I seem to have created some confusion.

1. I love peanut butter
2. Celery, in my humble taste bud's opinions, is a spice, and a nano-ounce is quite enough to flavor a soup.
3. There must be some chemical magic that allows peanut butter to turn a years worth of celery(one stick) into a quite tasty snack, of which I can eat many.

ps. I'm currently slow cooking a hamburger. I think I'll throw some PB on it.

 

[fresh_42]

I'm currently slow cooking a hamburger. I think I'll throw some PB on it.

Just maple syrup missing ...

 

[dkotschessaa]

I seem to have created some confusion.

1. I love peanut butter
2. Celery, in my humble taste bud's opinions, is a spice, and a nano-ounce is quite enough to flavor a soup.
3. There must be some chemical magic that allows peanut butter to turn a years worth of celery(one stick) into a quite tasty snack, of which I can eat many.

ps. I'm currently slow cooking a hamburger. I think I'll throw some PB on it.

Thai peanut sauce works :D

 

[OmCheeto]

Thai peanut sauce works :D

There is a peanut "sauce"?
hmmm...
Probably a good thing I did not know about this before, as I waited until this year, to become, Jabba the Om.