Random Thoughts Part 4 - Split Thread

[fresh_42]

You should call it being eccentric and humorous.

I find sophisticated not that bad, esp. in its slang meaning.

 

[rootone]

Isn't it cheaper over the long run to buy these and recharge them? Sorry, just curious, don't mean to tell you what to do.

I'm fairly sure that does work out to be economically favourable in the long run, although rechargeables are initially more expensive, and don't last forever

 

[fresh_42]

I'm fairly sure that does work out to be economically favourable in the long run, although rechargeables are initially more expensive, and don't last forever

Here you can buy a dozen of AAA in 99 Ct shops. My rechargeable ones are all broken. So, unfortunately, as long as one doesn't have especially high consumption, the one-way solution is far cheaper.

 

[zoobyshoe]

Isn't it cheaper over the long run to buy these and recharge them? Sorry, just curious, don't mean to tell you what to do.

You may be right. I just haven't looked into it.

 

[zoobyshoe]

Here you can buy a dozen of AAA in 99 Ct shops. My rechargeable ones are all broken. So, unfortunately, as long as one doesn't have especially high consumption, the one-way solution is far cheaper.

99 cent store batteries are really low quality and don't last nearly as long as the better brands. That's a situation where the joule thief is handy: you can use those cheap batteries much longer (if you're lighting LED's).

 

[collinsmark]

Holy carp. I forgot to like, come here and post for a year or so.

Welcome back, @dkotschessaa!

 

[collinsmark]

If you're an electronic tinkerer, and want to make a very efficient LED lamp, I suggest playing around with modern LED driver, integrated circuits (ICs).
https://www.google.com/search?q=LED+driver+circuit&ie=utf-8&oe=utf-8

The minimum voltage for these circuits might be higher than a single cell (e.g., 3 V is a typical minimum voltage for many of these circuits), but that can be managed easily enough by putting a few battery cells in series.

In simple terms, these circuits operate as a constant current source, dynamically outputting whatever voltage is necessary to produce the desired current. This is particularly advantageous to LEDs, since the LED's brightness varies more linearly with current rather than voltage. Like the Joule thief, they operate by "switching" circuits and can output a DC current (well, sort of a DC current) at a voltage higher (or lower if need-be) than the battery voltage, and without introducing a large amount of IR loss.

Advantages are:

• Wide range of input (battery) voltages. Without changing circuit components, you could connect three, four, five, whatever within reason, battery cells in series and it will not alter the individual brightness of each of the LEDs, nor will it greatly impact efficiency.
  
• Wide range of output (load) voltages. This means that you can connect one, two, three, whatever within reason, LEDs together in series, and it will not significantly affect the brightness of any given LED. The circuit will automatically adjust the output voltage such that the current through the LED chain is the desired current. [Edit: meaning you can adjust (reduce) the brightness of the lamp by merely shorting together some the output LEDs in the chain. The driver circuit will automatically compensate, and without significant loss of efficiency. (So long as the the LEDs are capable of handling a small transient in voltage, which they usually are.)]
  
• Usually requires a simple inductor rather than the transformer that the Joule thief requires.
  
• The desired current (usually the rated LED current) is simple matter of resistor value selection in the circuit design.
• Very efficient.

Similar to the Joule thief, when using these circuits ensure that the load (e.g., the string of LEDs) is connected to the circuit whenever powered on. Leaving the output open* can damage the circuit components just like what might happen with the Joule thief.

*[This might seem counter-intuitive if you're used to working with voltage sources. But with a constant current source, it's actually "safer" on the electronic circuity to short the output closed than it is to leave it open.]

 

[WWGD]

I think I had a bad trip from NyQuil. Could barely stay awake for like 3 days, together with feeling weird and depressed. Will look for something else to get a good night's sleep next time.

 

[fresh_42]

I think I had a bad trip from NyQuil. Could barely stay awake for like 3 days, together with feeling weird and depressed. Will look for something else to get a good night's sleep next time.

I know something that at least works well for me, but it's not OTC.

 

[WWGD]

I know something that at least works well for me, but it's not OTC.

I'll be sticking to my non-hard-core Chamomile compresses for a while now. Putting on my skin so they go directly to the bloodstream, I got scared straight.

 

[jim hardy]

Home Depot sells a blinding 6 volt LED lantern for $5.
http://www.homedepot.com/catalog/productImages/400/dc/dc658fb1-fd34-4106-839c-26b9897ebe5c_400.jpg
but it's kinda nerdy for the coffee shop scene.
i wonder what alternative battery you could fit in base of that lamp you pictured?

I put a rechargeable battery in my non-LED lantern , and added a charging jack behind the switch. Made it lots lighter.
3.6AH 6 volt NIMH camcorder battery cost a dollar at thrift shop , another buck bought a suitable car charger..
but the NIMH battery gave shorter bulb life -
Found this LED lamp at Walmart, works just fine now.

maybe an alternative battery would help Zooby...old jim

 

[WWGD]

I find sophisticated not that bad, esp. in its slang meaning.

Do you mean like complaining about wine? The other day I was offered a bottle of wine from 1978. The nerve! I complained right
away: This wine is old, I want some fresh wine! Isn't that sophisticated*?

* Ripped off from Steve Martin's " The Jerk".

 

[jim hardy]

I once found an empty Lafitte Rothschild wine bottle , took it home and used it for my barbecue sauce.
A friend dubbed it "The Baron's Own Blend" .

old jim

 

[fresh_42]

I'll be sticking to my non-hard-core Chamomile compresses for a while now. Putting on my skin so they go directly to the bloodstream, I got scared straight.

Mine is non-hardcore either and it doesn't get you addicted. However it passes the blood-brain-barrier, so ... Chamomile is at least no failure. If it's a cold people here use to say it'll last a fourteen days without a doctor and two weeks with. Hope it's not a flu. In each case: get well soon!

 

[WWGD]

I once found an empty Lafitte Rothschild wine bottle , took it home and used it for my barbecue sauce.
A friend dubbed it "The Baron's Own Blend" .

old jim

Did you drink to " Lafitte don't fail me now"?

 

[fresh_42]

I once found an empty Lafitte Rothschild wine bottle , took it home and used it for my barbecue sauce.
A friend dubbed it "The Baron's Own Blend" .

old jim

Cooool! Pretending to marinate your BBQ with Lafitte Rothschild! Guess that can be called sophisticated.

 

[collinsmark]

maybe an alternative battery would help Zooby...

Now that's an idea!

Rather than re-invent the wheel, maybe just power the existing lamp (or perhaps a similar lamp) using a portable, rechargeable power supply.

Although overkill, something like this comes to mind:
http://static.bhphoto.com/images/images500x500/Celestron_18777_Power_Tank_17_12_Volt_1405525891000_320348.jpg
http://www.bhphotovideo.com/c/buy/Computerized-Accessories/ci/3405/N/4069497395

Ignore the huge, built-in lamp. Rather what's of interest here is the dual, 12-volt output jacks (compatible with automotive, cigarette lighter adapters) and the other output jacks (in this case, 3, 6, and 9 volt outputs).

As another option, portable USB chargers will supply 5 volts, although I can't confirm if the electrical current limitations are suitable for the desk lamp.

I have something similar to what's pictured above (albeit a smaller, simpler version) that's used to power telescope motors and astronomical equipment.

 

[jim hardy]

Thanks, guys---

Did you drink to " Lafitte don't fail me now"?

In my circles it'd more likely be "Bubba Shot the Jukebox" .

Cooool! Pretending to marinate your BBQ with Lafitte Rothschild! Guess that can be called sophisticated.

hmm... perhaps "using class to abstraction" ?

 

[zoobyshoe]

Home Depot sells a blinding 6 volt LED lantern for $5.

but it's kinda nerdy for the coffee shop scene.

The criteria for the drawing lamp are that it should be small, lightweight, bright, and battery operated. Additionally, it has to have "lamp" configuration, meaning it sits on the table and the light can be conveniently directed downward at the drawing without blinding other customers. I already have three "blinding" LED flashlights of different make that are certainly bright enough, they just aren't made to direct the light downward. I can't hold the light and draw at the same time, either.

i wonder what alternative battery you could fit in base of that lamp you pictured?

It would actually be a cinch to bypass the AA battery clips add a 9v battery clip. Last night, using jumpers, I powered one with a 9v and it worked great, doubling the brightness. Still, it wasn't as bright as one of those flashlights with 30 LED's cause it only has 6 LEDs. Regardless, the idea of doing it this way and using rechargeable 9volt batteries is an improvement over the present way. The great thing about those lamps in my photos is that they are practically weightless and fold up to a small bundle. Very convenient for toting around in the backpack. They just need more and brighter LED's. Last week I ordered a crapload of LED's to experiment with, so I may be able to replace the 6 LED module in these lamps with a module of my own making that has many more packed into it.

What I've mostly been using lately is an old plug-in reading lamp from the 1960's that uses a 12 volt bulb, the same bulb used many places in cars. This particular one folds up, but is still too bulky for my taste, and the fact it must be plugged in limits where I can sit in the coffee houses. Everyone goes for the tables near wall outlets first, so often there's nowhere to sit where I could plug it in.

The other thing I've been working on is the idea of dismantling one of those really good flashlights and putting its guts into a folding lamp of my own design. What's been holding me up is that I'm really only conversant with fabricating in wood and a lamp like that ought to be sheet metal or plastic for durability and lightness.

 

[jim hardy]

Rather than re-invent the wheel, maybe just power the existing lamp (or perhaps a similar lamp) using a portable, rechargeable power supply.

i don't mess with cellphones but have seen batteries for them under $10 new.
https://www.amazon.com/dp/B00DD6LCQY/?tag=pfamazon01-20
3.8 volts sounds about right to replace 3 AA's.
Alkalines fade to around 1.3 volts at midlife, X3 = 3.9 volts

http://batteryuniversity.com/learn/article/choices_of_primary_batteries

Perhaps one could get a second battery for his cellphone, that way he could recharge it safely.. Modify the lamp to physically accept it. -

old jim

 

[jim hardy]

What's been holding me up is that I'm really only conversant with fabricating in wood and a lamp like that ought to be sheet metal or plastic for durability and lightness.

varnished oak or walnut would be a chick magnet

http://www.lokalart.com/media/catalog/product/cache/1/image/1102x472/9df78eab33525d08d6e5fb8d27136e95/l/o/lokalart-product1-/Fold-&-Hold-Lamp-|-Folding-Lamp-cum-Pen-stand-Mango-Wood-36.jpg

 

[zoobyshoe]

varnished oak or walnut would be a chick magnet

http://www.lokalart.com/media/catalog/product/cache/1/image/1102x472/9df78eab33525d08d6e5fb8d27136e95/l/o/lokalart-product1-/Fold-&-Hold-Lamp-|-Folding-Lamp-cum-Pen-stand-Mango-Wood-36.jpg

Wow, that's more than a little bit awesome. Great design!

 

[collinsmark]

i don't mess with cellphones but have seen batteries for them under $10 new.
[...]
Perhaps one could get a second battery for his cellphone, that way he could recharge it safely.. Modify the lamp to physically accept it. -

I recommend against lithium ion for this project.

It's not just the charging (if one overcharges a lithium ion battery, very bad things can happen such as fire and explosions) but also the requirements of the lamp. The lamp would need some sort of "smarts" to it such that it did not over drain the battery. If you deplete a lithium ion battery 100% it won't work again.

 

[zoobyshoe]

The great thing about those lamps in my photos is that they are practically weightless and fold up to a small bundle. Very convenient for toting around in the backpack. They just need more and brighter LED's.

The other thing I've been working on is the idea of dismantling one of those really good flashlights and putting its guts into a folding lamp of my own design.

I realized I have everything I need for a hybrid of these two ideas. I found I had a kind of hockey-puck shaped LED light that was very bright (tucked away in a drawer and forgotten about).

I removed its guts, and attached is a photo showing how the size is pretty much perfect for transplantation into one of the 6-LED lamps.

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?

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?

 

[jim hardy]

I recommend against lithium ion for this project.

It's not just the charging (if one overcharges a lithium ion battery, very bad things can happen such as fire and explosions) but also the requirements of the lamp. The lamp would need some sort of "smarts" to it such that it did not over drain the battery. If you deplete a lithium ion battery 100% it won't work again.

Thanks Colinsmark - i did not know about that feature of Li-ion.

I'm very happy with the NiMh in my flashlight - is has withstood considerable abuse.

http://data.energizer.com/PDFs/nickelmetalhydride_appman.pdf

Can NiMH batteries be substituted for alkaline batteries even though they are only 1.2 volts?Yes, for most high drain electronic applications NiMH batteries are ideal substitutes and you needn't worry about the apparent voltage differences. Even though alkaline batteries are rated at a nominal 1.5 volts, they only deliver 1.5 volts when they are fully charged. As they begin to discharge the voltage of alkaline batteries continuously drops. In fact, over the course of their discharge, alkaline batteries actually average about 1.2 volts. That's very close to the 1.2 volts of a NiMH battery. The main difference is that an alkaline battery starts at 1.5 volts and gradually drops to less than 1.0 volts. NiMH batteries stay at about 1.2 volts for most of their discharge cycle.There are a couple of cases where their actual voltage difference may be important to you. In the case of a device like a radio, where a higher voltage can mean a stronger signal, a fresh alkaline battery may be more desirable - but more expensive - than a rechargeable NiMH battery. This is also true for a flashlight, which will be brighter with the initial higher voltage of alkaline cells. This minor difference may not be important to you and is probably offset by the much lower cost of operating NiMH batteries. And keep in mind that the alkaline battery only has a higher voltage when it is fully charged. Once it gets to 50% capacity or less, it will be delivering a lower voltage than a NiMH battery.The one time when the voltage difference of the two is important would be in the case of a device that checks the voltage of a battery to estimate the amount of charge left on the battery. Because the voltage of an alkaline battery drops at a very predictable rate it's possible to estimate the amount of capacity left in an alkaline battery based solely on its voltage. (1.5 volts - fully charged, 1.25 volts - 50% charged, 1.0 volts - almost fully discharged). But a NiMH (or NiCd) battery stays at about 1.2 volts until it is nearly completely discharged. This makes it almost impossible to know the amount of capacity left based on its voltage alone. When a device that's using NiMH batteries indicates the battery is low, it's time to change the batteries now!

Return to top of page

it was blind luck i found a NiMh instead of a Li-ion.old jim

 

[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.