Step-Up Transformer for LEDs / Small Switches - RC Groups
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Jan 27, 2008, 06:43 PM
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Step-Up Transformer for LEDs / Small Switches


Does anyone know of a circuit that can be used to step up the voltage of a single cell (1/2 AAA size) to the 2.4V - 3V range? Either that or a light-weight step-up tranformer? I would like to be able to power my on-board LEDs with a single cell.

Currently, I am powering them with 2 non-rechargeable button cells (L44). This works fine, but they are throw -aways.

The light system that was just reviewed sounds great, but I would like to utilize several LEDs that I already have. I would also like the power to be separate from the power pack for a number of reasons.

Also, I am looking for a source for small, light-weight switches SPST to use as power switches for my LEDs. The size I am looking for is like the on-board power switches used in the Air Hogs Aero Aces and the Havok Helis.

Thanks, ahead of time for your help.
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Jan 31, 2008, 11:21 PM
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castlebravo's Avatar
Why not use a small single cell LiPo? If you have an old cell phone around you probably already have one. Single cell LiPo's are 3.7vdc nominal.

Chris Elliott
OMAS
Feb 02, 2008, 07:22 PM
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Thanks, for your input, Castlebravo. I am hoping to stay light-weight. 2 LR44 cells are nice and small and I even use smaller button cells, if I happen to scavenge some from some of my kid's broken dollar toys. This has also been a source for some LEDs too.

Part of my question is to see if anyone out there knows how to step up the voltage from 1.2V to the 2.4 - 3V range cheaply and lightly. There has to be someone that browses here that can point me to a simple circuit.

I'm just not sure if it can be done small enough and light enough.
Feb 03, 2008, 01:38 AM
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castlebravo's Avatar
Quote:
Originally Posted by Frankenator
Thanks, for your input, Castlebravo. I am hoping to stay light-weight. 2 LR44 cells are nice and small and I even use smaller button cells, if I happen to scavenge some from some of my kid's broken dollar toys. This has also been a source for some LEDs too.

Part of my question is to see if anyone out there knows how to step up the voltage from 1.2V to the 2.4 - 3V range cheaply and lightly. There has to be someone that browses here that can point me to a simple circuit.

I'm just not sure if it can be done small enough and light enough.
I know its not quite what your looking for but they make a Non-rechargable Lithium cell in a button package called the CR2032 (I believe). I used to use them to drive the LED's in my rotor blades for my helicopter. The cells are a little smaller than a quarter and wiegh about as much. They're also very common and you can get them anywhere you can buy batteries usually.
Anyway, hopefully someone will come up with a circuit for you. You might try looking for a DC to DC converter. They're similar to voltage regulators but will step up voltage also.

CHris Elliott
OMAS
Feb 05, 2008, 05:39 PM
Proud to eat Kraut ;-)
Julez's Avatar
http://www.dealextreme.com/products.dx/category.917

Browse through the category, and you will find various mini PCBs with various input and output voltages and currents.
Feb 05, 2008, 08:36 PM
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castlebravo's Avatar
Quote:
Originally Posted by Julez
http://www.dealextreme.com/products.dx/category.917

Browse through the category, and you will find various mini PCBs with various input and output voltages and currents.
Very cool site! Might have to use it for a lighting system for my Extra. Thanks Julez
Feb 08, 2008, 08:25 AM
Registered User

Cool Site


Julez,

Thanks! I think this is what I am looking for:

http://www.dealextreme.com/details.dx/sku.4735
Feb 09, 2008, 10:02 AM
Registered User

tiny lipo


i use the lipo from a havoc that was slightly chewed by my friends dog. (didn't think he could jump that high!) weighs next to nothing, and will run 10 led light tubes with no problem. even if the battery is "tired", running lights takes far less current than any motor. also, I read that those boards are drawing 1 amp from the batteries? they are talking about using them with aa alkalines/nimh, a 1/2aaa nimh would not have the power to run it. if you use a havoc/etc. battery, just use the switch from it. otherwise, discarded electronics are a great source for switches/led's/cap's/transistors/connectors/etc. for battery connectors, i used the terminals from the smallest pc board connector i have, soldered and heatshrunk to the battery tabs, and the male ends are just the led/resistor leads. works great, and its the lightest setup ive made yet. a 10" extension weighs .08g, with male and female connectors, and 3?g mag wire.
Feb 13, 2008, 02:06 PM
Registered User

Havoc Battery or Similar


Quote:
Originally Posted by roundeye04092

i use the lipo from a havoc that was slightly chewed by my friends dog. (didn't think he could jump that high!) weighs next to nothing, and will run 10 led light tubes with no problem. even if the battery is "tired", running lights takes far less current than any motor. also, I read that those boards are drawing 1 amp from the batteries? they are talking about using them with aa alkalines/nimh, a 1/2aaa nimh would not have the power to run it. if you use a havoc/etc. battery, just use the switch from it. otherwise, discarded electronics are a great source for switches/led's/cap's/transistors/connectors/etc. for battery connectors, i used the terminals from the smallest pc board connector i have, soldered and heatshrunk to the battery tabs, and the male ends are just the led/resistor leads. works great, and its the lightest setup ive made yet. a 10" extension weighs .08g, with male and female connectors, and 3?g mag wire.
I didn't realize about the current draw . . . Wow! That's way too much. Do you know where one can obtain the lipo you speak of?
Mar 03, 2008, 01:44 AM
New guy on the block
If you still want to build your own circuit, here is one that is extremely simple and lite, granted I don't think it will power more than one led per circuit (maybe two). But with them being so dirt cheap to make, I don't think its much of an issue.
Mar 11, 2008, 01:17 PM
Registered User
Quote:
Originally Posted by Frankenator
Thanks, for your input, Castlebravo. I am hoping to stay light-weight. 2 LR44 cells are nice and small and I even use smaller button cells, if I happen to scavenge some from some of my kid's broken dollar toys. ...

A single cell 100mah lipo only weighs 3.4g grams and costs less than $6 with shipping.
http://www.hobbycity.com/hobbycity/s...idProduct=4355

That might work?

If 100mah isn't enough they have some bigger ones
135mah - 4g
180mah - 5.1g
200mah - 6.2g
Mar 16, 2008, 02:56 AM
New guy on the block
I had some spare time on my hands tonight so I decided to build one of the Joule Thiefs I linked to earlier. Here are the results:

click me^


I wound the coils around a small ferrite core I salvaged from a disposable camera. I also salvaged the transistor out of it for the project. It's pretty bright considering that I am using a dead battery to power it, it could also be made much much smaller but I was just using scrap parts I had lying around.
Mar 16, 2008, 07:51 PM
Registered User
Thats awesome!
Jun 20, 2008, 07:13 PM
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Pete K's Avatar
I was gonna make the same suggestion as 'Shadow.
This link is along the same lines. Works fine with a single button cell.....

http://www.pm.keirle.com/joule/joule.htm


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