what to do with 100's of nine volts

L

lozaning

2[H]4U
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Mar 30, 2005
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any one have any interesting ideas of what i can do nine volts. i have like prolly around 200 at around 3/4 charge. i need to find seomthing usefull(halfways usefull atleast) as making big sparks and shorting them out so they exlpoad got old
 
ValeX said:
attach them all to a couple wires and lick it
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I licked a 300 volt battery once to see if it was good (they used to be called "B" batteries). WHOA! various psychodelic colors were seen before I almost blacked out.
 
Fenris_Ulf said:
Make some super multi-LED throwies.
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QFT. Great idea. Put a nice NIB magnet on there, find a hard-to-reach steel something-or-other (underside of a bridge, skywalk, whatever works), and go nuts. I also like the UPS idea, but that would be a bit more complicated.

 
those LED Throwies are cool...how long do they last? In terms of hours?
 
Frank4d said:
I licked a 300 volt battery once to see if it was good (they used to be called "B" batteries). WHOA! various psychodelic colors were seen before I almost blacked out.
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Where did you find a 300-volt B+ battery? The highest voltage I've seen is 90, and 67.5 was more common.
 
Make them into one huge 1800V battery and short it out :D

Yeah yeah I know there's too much internal resistance to do anything with that long of a string.
 
98EXL said:
those LED Throwies are cool...how long do they last? In terms of hours?
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Depends. Some people say 5-6 hours, some weeks. It mostly depends on the LEDs you use.
 
lozaning said:
folks i think we have a winner
any one know what kinda caps i would need to get to get the right voltage for leds?
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No capacitor would give you the right voltage. Capacitors block direct current.

A resistor is a useful device for limiting current. Divide 9 by the forward current shown on your LED's data sheet. For a typical LED, 15 mA is a safe forward current. 9 / 0.015 == 600 ohms.

You need to use a quarter-watt resistor; an eighth-watt resistor is too small.

A more interesting challenge is figuring out how big your magnet will need to be in order to make the throwie stick with the comparatively heavy 9v battery attached to it.

98EXL said:
those LED Throwies are cool...how long do they last? In terms of hours?
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CR3032 batteries are typically rated at 500 mAh, which means we can expect them to drive a 15 mA LED for about 33 hours. mAh rating for batteries isn't very standardized, so the empirical result will depend on where the manufacturer draws the voltage drop cutoff line and the minimum forward voltage of the LED you've chosen.
 
Frank4d said:
I licked a 300 volt battery once to see if it was good (they used to be called "B" batteries). WHOA! various psychodelic colors were seen before I almost blacked out.
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LOL!!!!!!!!!!!!....

you know.. mutimeters aren't that expensive these days...
 
mikeblas said:
No capacitor would give you the right voltage. Capacitors block direct current.

A resistor is a useful device for limiting current. Divide 9 by the forward current shown on your LED's data sheet. For a typical LED, 15 mA is a safe forward current. 9 / 0.015 == 600 ohms.

You need to use a quarter-watt resistor; an eighth-watt resistor is too small.

A more interesting challenge is figuring out how big your magnet will need to be in order to make the throwie stick with the comparatively heavy 9v battery attached to it.

CR3032 batteries are typically rated at 500 mAh, which means we can expect them to drive a 15 mA LED for about 33 hours. mAh rating for batteries isn't very standardized, so the empirical result will depend on where the manufacturer draws the voltage drop cutoff line and the minimum forward voltage of the LED you've chosen.
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as you can eassily tell i not that good when it comes to this kinda thing, so a link to what i would need would be very apreciated
 
lozaning said:
as you can eassily tell i not that good when it comes to this kinda thing, so a link to what i would need would be very apreciated
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I'm not sure I understand your question. What you need has already been provided; others have linked to instructions, and I've told you how to do the math to get the correct resistor value. What's missing?
 
I'd use two or three LEDs in series - more light with less wasted power on the resistor and you could use a 1/8 watt resistor. Also, the dropping voltage of the battery will reduce the current draw of the LED, allowing it to last longer than what just the battery ratings and LED specs would seem to indicate.
 
mikeblas said:
I'm not sure I understand your question. What you need has already been provided; others have linked to instructions, and I've told you how to do the math to get the correct resistor value. What's missing?
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i guess what i am asking is will these work?
http://www.radioshack.com/product/i...&cp=2032058.2032230.2032267&parentPage=family

and i know how to make the led throwies form those directions but as far as hooking them up to a nine volt a wire diagram would be apreciated ;)

edit http://www.lsdiodes.com/shop/index.php?main_page=page_4
i think im going to try making some in series and some using resistorsm i'll be sure to post pictures when im done
 
lozaning said:
i guess what i am asking is will these work?
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I don't know; it depends on your LED. Some of the lower values should work, but you only get a few because you're buying an assortment and not a bunch of the same value.

Thinking of common LED parameters, the 470 ohm version is the most likely to work. (Did you do the math, or are you expecting me to do it for you?) But you only get 8 in that set.

The 1000 ohm resistors will work, but the LED will be pretty dim. You get ten of those.

Code: 
Battery +  ----resistor----\
                            LED
Battery -  ----------------/

I'd proceed by getting the LED, then soldering your resistor to one leg. Then, you should be able to touch the unfastened resistor leg to one terminal of the battery, and the unfastened LED lead to the other terminal of the battery.

If the LED glows, you're ready. Make a note of which polarity you have; did the resistor go to the + side of the battery, or the - side?

If the LED didn't glow, you should reverse it; touch the lead you have on + to -, and the lead you have on - to +.

Bingo, you're done.
 
mikeblas said:
(Did you do the math, or are you expecting me to do it for you?) .
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well i just wanted some help.

i baught the 10megohm resistors and those dont seam to work, but after messing around and burning around 5 leds up, i figured out that 4 is the magic number for running in parralel. so now i have 3 led flashies. pictures coming soon
 
lozaning said:
well i just wanted some help.
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Do you think I've not helped you enough?

lozaning said:
i baught [sic] the 10megohm resistors and those dont seam [sic] to work,
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Had you done the math, you would've known why.
 
could we get a picture of what you have made showing the wiring and all that stuff or a very detailed diagram
 
mikeblas said:
Do you think I've not helped you enough?

Had you done the math, you would've known why.
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but i dont know how to do the math.
anyways, thank you for the help you gave me, it is very much appreciated
 
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so um does anyone know how to do the math for how many leds you could hook up to a car battery?
 
The math depends on several factors such as how many LEDs, what color, what current, the battery, how long you want the LEDs to run, whether the battery is being charged.

Let's say I want to connect 600 blue LEDs, and each LED is going to draw 20 mA. The battery is initially about 12.6 volts (not charging). And blue LEDs have a forward voltage of 3.5 volts.

I would make 200 strings of 3 LEDs, each with a resistor. For each string the resistor should be R= (12.6 - 3 x 3.5)/.020, or 105 ohms. Lets use a standard 100 ohm resistor, so the current for each string will actually be I = (12.6 - 3 x 3.5)/100 = 21 mA

Then connect the 200 strings to the battery all in parallel. The total current for 600 LEDs is 600 X 21 mA = 12.6 Amps. A car battery rated 200 AH (amp hours) should power 600 LEDs for 200AH/12.6A = 15.87 hours. Actually less since the battery voltage will decrease over time.
 
Frank4d said:
A car battery rated 200 AH (amp hours) should power 600 LEDs for 200AH/12.6A = 15.87 hours. Actually less since the battery voltage will decrease over time.
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Amazingly enough, it's actually the reverse. What happens is that as the battery gets discharged, its voltage decreases, but the LEDs drop the same amount of voltage. Which means that less voltage is dropped across the resistors, and so (I=V/R) the current decreases. And as the current decreases, the battery discharges more slowly. The LEDs will be dimmer, but they'll still be lit for far longer than 15 hours.
 
True. But I already wasted 15 minutes on my previous thread and didn't want to any more math. :D
 
Skaterpunk said:
so 600 blue LEDs. 200 strands of 3 each with a resistor would work on a car battery?
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According to the other posts, yes, this should theoretically work. However, it's not adviseable.

Let's say you make a mistake when you connect one of the LEDs (reverse it perhaps), or everything is wired correctly and LED dies. You then have a string of 200 LEDs which won't light up, meaning you'll have to use a multimeter to check for continuitiy between each and every one in order to find the dead component.
 
Stuey83 said:
According to the other posts, yes, this should theoretically work. However, it's not adviseable.

Let's say you make a mistake when you connect one of the LEDs (reverse it perhaps), or everything is wired correctly and LED dies. You then have a string of 200 LEDs which won't light up, meaning you'll have to use a multimeter to check for continuitiy between each and every one in order to find the dead component.
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Actually, 3 LEDs wouldn't light up, the 200 strings are in parallell.

If you were using these in a car, you would have to deal with the voltage variance between the battery by itself and the alternator charging it. That can be between 9 and 13.8 volts. Two LEDs in series is about right - three in series means that the voltage drop across the resistor can vary to a great degree which means the current varies a great deal. I found this out when building LED turn signals and brake lights for my motorcycle. I had to re-do them from series strings of 5 LEDs to two strings of two and three LEDs.
 
Fenris_Ulf said:
Actually, 3 LEDs wouldn't light up, the 200 strings are in parallell.
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LOL, for some reason I read and reread the posts and still thought that they were referring to 3 strings of 200 LEDs. I kept thinking that noway it could even work at all, but I figured maybe you guys knew something that I didn't. LoL, THAT'll teach me to post after a sleepless night.
 
Stuey83 said:
LOL, for some reason I read and reread the posts and still thought that they were referring to 3 strings of 200 LEDs. I kept thinking that noway it could even work at all, but I figured maybe you guys knew something that I didn't. LoL, THAT'll teach me to post after a sleepless night.
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The problem here is that you haven't had enough beers today. If you re-read my post above... I said:
I would make 200 strings of 3 LEDs, each with a resistor.
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ValeX said:
attach them all to a couple wires and lick it
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someone taught me as a kid a good way to test a 9v is to lick it.. then as i got older i was about to lick one to check it and i was like WHAT THE F*** am I licking a battery for?! hehe so that was an easy habit to break :p
 
i got my throwies made but the magnets i have dont hold them up to things very well, and throwing them long distences and having them stick is very hard. so i still have at least 180 somthing nine volts left, any more ideas? any type of cool cercut type thing i can make that would run of nine volts and ammuse me for a while
 
LoL, I have this visualization of you actually throwing the 9 volt batteries. With the momentum a flying 9 volt has, I would be VERY surprised if it stuck to anything even with moderate strength magnets.
 
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