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Led powered by 9v Answered

Hi all. I am new to this forum and need some help. I want to mount an led strip to the bottom of a roller skate. Everything I find already made up requires 12v. I need to keep the setup as small as possible for mounting reasons. How could I go about making a 12vdc led circuit work off a 9v battery or how could I wire up some led's on a flexible strip powered by a battery. I am thinking 9v because I can purchase a rechargeable set without draining the bank account each time. Any suggestions are welcomed. I have about 6" in length to mount the strip to. I would like multi color led but one solid color would also be fine. Thanks again for any suggestions.

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kadris3 (author)2007-09-03

ultra bright LEDs can be had fm unclecytheledguy.com. with 9 volts (rechargables are usually 8.4vdc and 7.2 for the cheaper ones) u can series up two LEDs w a droping resistor. use ohms law to figure resistance.
supply voltage -6.8(forward vdc of two series leds) =left over voltage/.02=resistance in ohms. 8.4-6.8=1.6/.02=80 ohms. series and parallel these two until you have the desired effect. each string draws 20 miliamps.
an 8.4 batt has about 150ma or so total. certainly less than 200. if u need more info or clarification feel free to contact me . good luck w ur project. lite the world.

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Patrick Pending (author)kadris32007-09-03

Are you on commission kadris3? I only ask because you seem to mention the same supplier on most of your posts.

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kadris3 (author)Patrick Pending2007-09-03

no, just helping out a friend. he's lower than most of the highly tooted suppliers to whom people refer. in some cases welton and others toot their own horn. most readers can filter. i actually use the url less than 24 % so your 100% is unfounded. i teach electronics so most of my stuff is instructional in nature. many are new and lack my 50+ years of electronics experience. if you are unhappy, feel free to avoid my posts. good luck. lite the world.

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Patrick Pending (author)kadris32007-09-04

You are not being truthful there are you?

Anybody who knows how to use a search engine properly can find out that:

- Kadris3 buys job lots (1000's) of LEDs from e-Bay Hong Kong

- Kadris3 has the same HAM radio callsign (K1tes) as Uncle Cy.

- Kadris3 username is similar to Cyrus III

- Kadris3 has the exact same hobbies as Uncle Cy

- KADRIS3 is UNCLE Cyrus!

There is a lot more evidence and it is all out there for anyone to see.

The 24% advertising that you say you do is in breach of the Instructables Terms of Service and so is pretending not to be Uncle Cy

Extract from the Instructables TOS

You agree to NOT use the Service to:

c. Impersonate any person or entity, including, but not limited to, a Instructables staff member or volunteer, or falsely state or otherwise misrepresent your affiliation with a person or entity;

g. Upload, post or otherwise transmit any unsolicited or unauthorized advertising, promotional materials, "junk mail," "spam," "chain letters," "pyramid schemes," or any other form of solicitation;

BTW: I'm not unhappy -you made me smile ;-) <Big Thanks>

As for "lite the world" - just why would I want to do that exactly?

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One more thing... Do a who.is lookup on www.unclecytheledguy.com I had an ear to ear grin when I read it :-P

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Yep, that explains where he got his user name. Cheers, Pat. Pending

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rsfaze (author)Patrick Pending2007-09-04

why hijack my thread to talk about this?

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Patrick Pending (author)rsfaze2007-09-04

Very sorry rsfaze but it's here that he posted his advertisement and here that it needs to be addressed. If the commercial spammers aren't brought to task then the whole site will suffer not just your thread. I am sure your thread will survive and people will continue to give you advice if you need it (hopefully advertisement free!). Cheers, Pat. Pending

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rsfaze (author)Patrick Pending2007-09-04

I understand and do thank all of you for your advice. I found a few sites on this site that I will be ordering. I have to break out my soldering gun and start practicing. Its been awhile and the kits I ordered do not come assembled.

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Patrick Pending (author)rsfaze2007-09-04

There are a number of soldering instructable on this site if you need some pointers. Will the LED's be visible from the side of the skate or will they be on the bottom of the skate and be visible when you lift it ? Ultraviolet LEDs would be really cool as they would cause the ice around the skate to fluoresce giving a (perceived) floating effect. I don't think these would work in bright light conditions though. Another thing that might be worth considering is to use laser diodes projecting down onto the ice. The lasers would trace out the motion of the skates onto the ice. Cheers, Pat Pending

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rsfaze (author)Patrick Pending2007-09-04

the kits I found would be facing down. I am talking about roller skating not ice skating or the UV would be awesome. I found a couple of kits although all the same color LED kits some with a chasing effect. My ideal thing I found would be a flashing cellphone battery that has multiple led's with flashing and chasing effects. Maybe I will learn enough here to make something like that.

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whatsisface (author)rsfaze2007-09-04

This is something that needs to be said, sadly.

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kadris3 (author)whatsisface2007-09-03

same comment. see post above. i was only trying to help those w less experience. if u find someone cheaper please let me know. i'm always looking for a bargin. good luck. lite the world.

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rsfaze (author)2007-09-08

everyone has been of such great help I have another question for you guys. I ordered the 9v kit and its on its way. I am going to try this but I think I found something even better. Check this out http://www.oznium.com/thin-led-strip. My question is it says it need 12v. Anyways I could power this would something else that would be portable for skating. I know since they require more power the battery will need to be larger but given the light these give off I think it would be worth it. Please let me know if this is possible. Thanks again

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Patrick Pending (author)2007-09-01

The Electroluminescent wire (glow wire) Kiteman suggests is really cool stuff. I bought a unit for my daughter and she loved it. - I just noticed while I was typing this that you have tried it already.

If you want to use LEDs then 4 in series across a 9V battery (with or without a limiting resistor) see this post here.

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Goodhart (author)Patrick Pending2007-09-04

This is fine as long as one remembers that unmatched LEDs may give you light (for awhile) out of some, and nothing out of others. So you can put LEDs in series with only one resistor for the whole series string. Just add up the voltages of all the LEDs in the series string. This should not exceed 80 % of the supply voltage if you want good stability and predictable current consumption. The dropped voltage will then be the supply voltage minus the total voltage of the LEDs in the series string. Also do not put LEDs in parallel with each other. Although this can work, it is not reliable. LEDs become more conductive as they warm up, which may lead to unstable current distribution through paralleled LEDs. LEDs in parallel need their own individual dropping resistors. Series strings can be paralleled if each string has its own dropping resistor.

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Patrick Pending (author)Goodhart2007-09-04

"This is fine as long as one remembers that unmatched LEDs may give you light (for awhile) out of some, and nothing out of others." Are you talking about series or parallel here?

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Goodhart (author)Patrick Pending2007-09-04

In series, unmatched LED's can cause trouble. If all are matched, ignore my first comment...sorry I wasn't clear, I was in a rush earlier.

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Patrick Pending (author)Goodhart2007-09-05

What condition other than operating close to the gap-point would give you light out of some but not out of others?

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Goodhart (author)Patrick Pending2007-09-05

Ah fiddle sticks, sorry about that. I WAS speaking of parallel configurations ( haven't fooled around with this stuff for a number of years now, so I forgot) If you mix colors in parallel, say if you paralleled a red (~2.3V) and two blue (~3.5V), the blue LEDs would not light. Why's this? Because the electricity is going to take the easiest path it can to complete the circuit and in this scenario the red LED requires less energy, leaving the two blue unpowered and lonely. To fix this you would need to stick a resistor onto the leg of each LED to 'equalize' all of the LEDs. My bad.

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rsfaze (author)2007-09-03

I am trying to come up with something like this http://www.goldmine-elec-products.com/prodinfo.asp?number=C6829.

I want some led prefer them in some pattern lighting sequence. I am mounting them to the bottom of speed skates so very limited in room. I am looking for something that will run at least 3-4 off a charge. Sorry if i wasnt clear in what I wanted to achieve. I appreciate all the input from you guys

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Patrick Pending (author)rsfaze2007-09-03

For speed skating I would imagine the weight and bulk of the battery on the skate would be an issue. Why not buy one or two of the kits, mount the PCB somewhere convenient on the skate then simply run wires from the PCB to the LEDs then you can place the LED's in the right location for best effect. You could have a single battery on a belt clip and wire down to each skate plugging the wires into sockets wired to the PCB. The leg wires can be concealed in a number of ways. BTW: The C4431 circuit also looked like it might fit the bill.

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rsfaze (author)Patrick Pending2007-09-03

good idea about mounting the PCB away from the skate. I actually would have the room for the 9v battery on the plate of my skate. I want to try and keep everything under the skate to keep any wires from being seen. I am going to order a couple of these kits. I forgot to mention I want to run colors so the C4431 seems to come with all red leds. I guess I could switch them out with color ones for the same requirements.

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rsfaze (author)rsfaze2007-09-03

of course the link doesnt work. if you go here http://www.goldmine-elec-products.com than look under
Home > Kits > Flashing LED Kits. This is what I want. I may just buy this kit although its been years since ive solder'ed something

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rsfaze (author)2007-09-03

another direction maybe.. what size are the LED's that are used in a flashing cell phone battery. This would be good because it could be its own source for power. Could I use more led's if using these very small led's?

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Patrick Pending (author)rsfaze2007-09-03

I am not sure that you have grasped the advice that has been given (I might be wrong). Maybe, If you explained exactly what you were trying to achieve we could also be more specific with our help.

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Kiteman (author)2007-09-01

If you're after running lights, have you thought about electroluminescent wire? I can run off rechargeable AA batteries in small power packs.

Try this UK based supplier.

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Patrick Pending (author)Kiteman2007-09-01

Do you have a mains adapter as well?

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Kiteman (author)Patrick Pending2007-09-01

...I won't tell you where it gets plugged in, though.

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Kiteman (author)Kiteman2007-09-01
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rsfaze (author)2007-09-01

I have already purchased and ran the el wire that runs off a aaa battery. For the application this does not give off enough light. I skate in some rinks that are not very dark so I need something pretty bright like an LED.

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