Step 2: Parts and Tools

Step-up converter parts
The parts for the step-up circuit can be obtained from an electronics distributor such as Digikey.

U1 -- MAX756 3.3V/5V step-up DC-DC converter, 8-pin DIP package [Digikey# MAX756CPA+-ND]
C1 -- 0.33 F 5.5V capacitor, coin package [Digikey# 604-1024-ND]
C2,C3 -- 100 uF 6.3V aluminum electrolytic capacitor, mini radial [Digikey# P803-ND]
C4 -- 0.1 uF 25V ceramic general purpose capacitor, through-hole [Digikey# BC1148CT-ND]
L1 -- 22 uH RF choke, axial [Digikey# M8138CT-ND]
R1 -- 1k, 1/4W general purpose carbon film resistor, axial [Digikey# 1.0KQBK-ND]
D2 -- 1A 20V Schottky diode, axial [Digikey# 1N5817GOS-ND]
D3 -- If you are not able to recycle the original LEDs in the flashlight because the leads were clipped too short, you can use any 2 mA LED, round T1 3mm [e.g. Digikey# 475-1402-ND]

Dynamo keychain flashlight
I used a dynamo LED keychain flashlight which was marked as AIDvantage and made by LTA, Inc. (item# 02119) for this project. There are a variety of these sized flashlights on the market made by different manufacturers -- I've seen them at grocery stores (Giant on the East Coast) and computer stores (Microcenter). You can find them online by Googling: dynamo keychain flashlight. They usually cost less than $5.

I discovered there are some minor variations between flashlights made by different manufacturers. One flashlight I got at Microcenter did not have a circuit board for the LEDs -- the LEDs were just soldered directly to the battery. This LED circuit board is nice but not required. If you find that there's no separate circuit board for the LEDs, you can just solder the respective positive and negative leads of the LED+resistor combo and output cable together. A little hot glue inside the faceplate near the LED and output cable can give the assembly some mechanical strength. The other variation was that leads on the switch on this version were also soldered slightly differently to the battery. Otherwise, it was pretty much identical.

Output cable
I used a USB A male to mini-B USB male cable scavenged from a dead MP3 player as the output cable. I chose this cable because the mini-USB input is common for small circuits. Since there are 4 connections inside this cable, you have to figure out which wires are the positive & negative leads. However, you can use any output cable type you want if you know the polarity.

To test the circuit, you will also probably want to have the complementary jack available for the output adapter. I de-soldered the mini-B receptacle from the dead MP3 player and connected red and black wires to power 5V and ground pins, respectively.

You will need the following tools to build and test the modified dynamo:

-- wire stripper
-- soldering iron, solder, & flux (this Instructable assumes you have soldered before)
-- voltmeter & test leads
-- small Phillips screwdriver (for opening the flashlight case)
-- electrical tape
-- small wire cutters
-- small pliers
-- tweezers (optional, but recommended)
-- adjustable arms vise, third hand tool (optional, but recommended)
-- small flathead screwdriver (optional, but recommended)
-- hot glue gun (optional, but recommended)
-- hobby knife (optional, but recommended)
<p>Does the step up converter limit current? I have a single 10Ah 3.2V lifepo4 battery left over from an EV project and would love to turn it into a field charger for my andriod tablet</p>
<p>I like the idea but I am going to incease the size of the leds and as you fit a super capacitor to see what happens hopefully I should be able to get 10min of light </p>
Since I'm trying to create this Joule thief supply with no dynamo flashlight, I'd like to know the reference for the diode D1.
Very detailed tut, just what i was looking for, got a few of these from DX with the intent to make a hand cranked arduino project, and your sweet little circuit origami is just what i needed to give these babys a little extra kick :) im actually thinking of custom casing with 2 generators on 1 crank, and (if i manage to tweak the components and still get it to work) will prolly try rebuild your circuit with a bigger capacitator that can deliver more mA. <br> <br>I want there to be enough power for some cool things, was thinking of a small rgb pixel matrix and some buttons and joysticks to make a hand cranked little handheld game :D though its kinda far fetched looking at the needed power and what can be achieved with these hand crank units, even when beefed out with your circuit. <br> <br>Either way, thanks for the great ideas &amp; details! <br>
Wow, I really like your origami :-) I bought one of these keychains from dealextreme, and instead of simple coin cells they contain a 160mAh rechargeable battery ! (about the same dimensions as your 0.33F capacitor). Seems ideal for your project. I've got a question about the inductor you used, the datasheet specifies a much higher saturation inductor, did it work well anyway or did you have issues with the max. current or efficiency ?
Can you post a link to the keychain from dealextreme that had a 160 mAh battery? Did it include the actual charging circuit too? That could be an even better candidate for this project. I will do a test with the breadboarded version and a variable power supply and see if the efficiencies are close to the datasheet's.
This one : <a rel="nofollow" href="http://www.dealextreme.com/details.dx/sku.12932">http://www.dealextreme.com/details.dx/sku.12932</a><br/>Actually, it's 20mAh, and not 160mAh ... It's nearly identical to the keychain you used. It brings me another question : why didn't you use the battery that came in your keychain ?<br/>
or this<br> <a href="http://www.harborfreight.com/mini-dynamo-keychain-flashlight-99859.html" rel="nofollow">http://www.harborfreight.com/mini-dynamo-keychain-flashlight-99859.html</a><br>
I really like the origami, but isn't you motor producing over 5 volts? <br>(therefor shouldn't a step down switching regultor be used?)
Great tutorial : <br> <br>Stupid question, What would happen if you increased the size of the capactor?
Does the step up converter limit current? I have a single 10Ah 3.2V lifepo4 battery left over from an EV project and would love to turn it into a field charger for my andriod tablet
After reading on the data sheet I realize my question is vague. The datasheet shows 500mA in the setup I described, my real question is if I put a large load on this device will it limit current to the 500mA or will it deliver more and burn up?
this &quot;dead bug&quot; packaging is a work of art!
Agreed. I prefer a experiment card as it's easier for me to connect the leads. It seems that I don't have a talent for creating a dead bug!<br><br>Really impressive instructables, it's a piece of art. Thank a lot for that information about MAX756, it'll solve some of my problems about a good 5V source!!!!! :D
I built something like this a while back, but it was with a dead dynamo flashlight that had the little plug on the side for cellphones. I pulled the LED assembly out and hot glued a USB port in its place, soldering it to the pins on the power output on the side
Classic Radio Shack mini-multimeter! I got tired of replacing those coin batteries and modified it to work off three AAA batteries. I haven't replaced them in three years now! Haha.
Great instructable, very clear and well designed! Would any of the other maxim DC-DC converters work for this? The max856 looks like a good alternative.<br>
You know you can find little dynamo keychain things like this that actually have USB out on them. I've seen them on ebay for less than $5. It might be a lot easier to add a battery to one of those than to make a step up circuit.
well done i want that typ of flash light &gt;.&lt;
Really nicely done mate everything with pictures and stuff :D gonna ask around for a dynamo flashlight :P would love to charge everything :D
<p>I DONT GET WERE R1(1) GOES IN STEP 10 (C)</p>
&nbsp;If you look at the 2nd and 3rd picture, D3+ is the end that is being soldered to R1(1).
<p>I was&nbsp;struggling to put&nbsp;a similar max756 circuit&nbsp;with usb in the removable solar panel/battery pack of my&nbsp;<a href="http://www.ikea.com/us/en/catalog/products/90154371" rel="nofollow"><font color="#ff5200">Ikea Sunnan</font></a>&nbsp; lamp, to use it as an&nbsp;PDA-battery backup. <strong>Your origami idea&nbsp;is a very space efficient&nbsp;solution! </strong>( But I wont not solder directly on IC, too affraid to burn it).<br /> <br /> I also plan to hook the battery pack to a forced ventilation woodgas stove ( <a href="https://www.instructables.com/id/Easy-large-portable-woodgas-stove/" rel="nofollow">like this </a>) and use it on&nbsp;a trek in the Spanish Pyrenees.&nbsp;While I'm at it, I could even&nbsp;stick a peltier to the stove and use heat to recharge the battery pack&nbsp;a bit. If I ever get to making an instrucatble of it, I'll link to yours.<br /> <br /> Keep up the good work!<br /> <br /> &nbsp;</p>
Wow!<br /> This Is a very Professional Instructable.<br /> Wonderful Pictures By the Way!<br /> Well Done!<br /> 5 *<br />
great :)
Thank you, Bongmaster.
just got one off ebay and looked inside.. not much space to work with XD gonna see what i can come up with tho :) prolly wont be as compact as ures but i will be making it part of a permanent microcontroller project anyway :)
Hi Griswold Lighting - great Instructable, thank you! A couple of questions, with reference to the the MAX756 datasheet: - if I want the output to be 3.3V, I just need to tie pin 2 to the input voltage (high) by moving its connection to the other side of C3 (or even connecting it straight to pin 1)? - If I wasn't too worried about getting it all back into the case, what's the easiest way to upgrade the stored capacity? Can I just make C3 as big as I can get? I want to hook this to a micro wind turbine to power a small weather station (actually, mainly the XBee that's transmitting the data). Thanks in advance for you help.
- Yup, to get 3.3V you could just tie pins 1 and 2 together. The circuit would work with a micro wind turbine if the turbine is putting out between 0.7V and 3.3V. If the turbine is actually generating >3.3V, you might be able to just use a voltage regulator. - C1 stores most of the energy. If your volume isn't limited you could use a bigger cap for C1 as long as it was rated for at least 5.5V (if you're stepping to 5V) . The charging time will be proportionally longer.
I like the idea. Butttt if you did it with a bike dynamo you could get fit and charge battery. Just a though I think way to much.
A bike dynamo might be the next project. I chose this small size so I could potentially attach it to a development board.
Wow! Nice details and great pictures.
Thanks. I have an SD card filled with pictures of it.
That's fantastic!
Thank you.
is there a way to put an extra 325 ma on this
Not 'as-is' with this tiny motor and circuit...I'd guess the highest it can go is 100 mA. You could probably get 100's of mA with a design based on the larger flashlights.
Great solution!
Thanks NoodlesVA!
Nicely done. I want one!
Thank you. If you have the time it's a fun build.
Thank you very much.
All I need to do is recruit my army of hamsters and connect their wheels to this generator and I can RULE THE WORLD!
An even better reason to use the keychain-sized dynamos....
This is one of the better instructables I've read for procedural details and instructions... and good pictures. Thanks. I'll keep an eye out for the crank lights, sounds like a neat project. And I love the origami.
Thank you. It was a fun project to work on -- it took awhile to find a way to get the parts as compact as possible.
can i use the step up circuit with a 1.5v DC battery?

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