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Step 7: The Process: Rapid Prototyping

In reality, what I did was look through the Digikey catalog, where I only found the DN7418 inductor (the other one was somewhat hidden in the RF inductor section). And it showed up before the Mouser box, so I spent an hour or two making up a prototype.

The circuit itself is simple, I want one large electrolytic cap for low frequency smoothing on the battery, and an output cap pair (electrolytic and one ceramic cap for high freq. smoothing). I also need the chip, a reference voltage capacitor, the inductor and a schottky diode to finish off the boost regulator. I happen to have some 1N5818's, which are often used as schottky diodes in boost regulators. I also need a USB type A female jack, of course, and two holes to solder the battery pack into. You can compare the schematic to the topology diagram in step #3 keeping in mind that this chip has an internal transistor switch.

All these parts must fit into the space left over from the battery pack. I make EagleCAD library parts for the inductor and chip (the rest are already there) and lay out the board. I'm not going to detail making library parts in eagle or pcb layout, others have done so already. Use whichever software you want, I like Eagle because there's a free version available for download if you're just making small PCBs.

Since I am know this is just a prototype version, I make the PCB single sided -- for easy etching. I also make the traces really large. I print out a paper version of the PCB and punch the parts through to verify that they're the right shape/package.

I get my etching setup together, turn on the heater for the etching tank, and print out a bunch of tiled PCB layouts on toner transfer. I transfer the toner onto a single sided PCB and etch it in the tank

Then I clean off the toner transfer, drill the holes with a dremel drill-press with carbide drill bits, and cut out the shape.

Then I solder the parts in, and fit it into the case with the battery pack, using double-sided foam sticky tape to hold down both the battery holder and the PCB without shorting the PCB to the metal tin.

OK, done!

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<p>Would this project work better with a 9 Volt battery, instead of the 2 AA?</p>
<p>good idea thank you</p>
<p>does anyone know if you HAVE to solder the wires? And why mine burns up before I even plug in the USB??</p>
I made this from the kit but on my iPhone 5s it charges for about 20-30 mins then it says &quot;This accessory may not be supported&quot; and stops charging. Any advice?
<p>can i use a coiled inductor of 22 mH? Its hard to find the one mentioned in the project!</p><p>please reply soon</p>
It will probably be fine. I'm pretty sure the inductor is just an AC choke, but you'll probably experience some efficiency loss due to the higher DC resistance.
<p>how long does that battery normally last?</p>
<p>Could I stumbleupon http://www.umi-zero.com/</p>
<p>A nice effort and I salute your spirit for <br>developing such a nice product. Well, I even purchased one from Amazon <a href="http://amzn.to/1BrwTY9" rel="nofollow">http://amzn.to/1BrwTY9</a> <br>that can charge up to 6 devices including the latest iPhone 6/6 plus, Galaxy <br>Note 4, Nexus 6, iPad Air 2 simultaneously in just 2 hours with its unique auto <br>detection feature. Currently the charger is under 20% discount after applying <br>this coupon code: 20OFFANU</p>
Where are the parts? No idea which caps i should us if I do make one... It is genius. My 9V battery charger lasts for a few minutes.
<p>The parts are in the .sch</p>
<p>This is very well-done and sexy! I want to make something very similar, and I was thinking it would be cool to use rechargeable batteries AND a small solar panel. The thing could be left on a car dashboard (assuming the sun isn't too bad for the batteries) and it would slowly charge the rechargeable batteries. THEN you could take it along and use it as an emergency power-source for phones. No expensive battery replacement, and no worrying about whether the sun is powerful enough. <br><br>Also: I'm not the most perceptive person, so correct me if I'm wrong: but why on earth do they not sell things like this in stores? People whose phones are dying are a pretty damn big demographic (and a desperate one at that!) They should sell these things pre-loaded with batteries at airports, supermarket checkout lanes, etc. What's going on with that?</p>
<p>I found solar-battery chargers on Amazon... check out PowerAdd and Levin SolStar to name a couple. they're about $20-$30 and work fine for me (when I RTM). I don't remember seeing chargers that take AA batteries though. </p>
Mine heats up a lot got any suggestions?
&nbsp;do any of u know how to add a switch and led to this kit
<p>a switch you would just wire directly onto the red cable coming formt he battery, the LED you would want to place right behindm the switch, probaply you would need a resistor to make sure the LED doesn't get a too high voltage.</p>
<p>indian not max ic max ic equivalent ?</p>
<p>just wonderful..a detailed project...</p>
<p>Great innovation!! But I still prefers the usual <a href="http://www.sfcable.com/portable-power-bank.html" rel="nofollow">power banks</a> because of some reasons that is it is not gonna last for a long time, and these batteries can't be able to charge my i phone even to 80%...</p>
<p>u could also use 2 dc batteries and put them in a watch case or can but the same idea just alittel more work needed to make.</p>
<p>Could I use hot glue instead of foam tape? Also, would this work? </p><p><a href="http://www.amazon.com/DROK-Power-Converter-Module-Charge/dp/B00C93Z8JY" rel="nofollow">http://www.amazon.com/DROK-Power-Converter-Module-...</a></p><p>Thanks.</p>
<p>can i use 4x aa batteries?? thanks..</p>
Hi..I am a student pursuing my third year in engineering..i have taken minty booster as my project..i have successfully implemented this circuit on the breadboard and got the output..but in the PCB m not being able to get the output..it would b really helpful if i get the layout of PCB..thanking you!
Did the popcorn come with the stuff? if it did what site do you order from that's good customer service!
when will u make a solar powered one
Hey Can dis circuit be used for a 4-volt input battery(18650 kind li-ion cell,,2400mAh)???? <br>coz i got six of dem from a laptop battrey..... <br>It would be great if you would help.......thanks
i don't know for sure, but oh my god! Use proper english! its not that hard to type an extra 3 or 4 keys on your keyboard is it?
Only as hard as hitting the shift key to capitalize your sentences. Also, Yes, This can be used with a 18650 Laptop cell. Got a 3AH one hooked up to mine and used a cheap gutted 18650 charger and a 6V solar panel to charge mine. No issues for the past 7-8 months.
I was looking through the instructable and decided that I wanted to add in the low battery LED. I found the circuit diagram in the version 2 schematic showing how to wire it. <br> <br>My question is regarding R3, the value is not mentioned? Also why is it neccessary if your using two 1.2V cells in series since it gives you 2.4V then while the LED that I want to use has a max forward voltage of 2.4V. This falls within the rating? <br> <br>Or is the resistor used for when your using 1.5V batteries i.e. 3V? Anyways was just wondering if someone could help me out with the value? Thanks in advance. <br> <br>Really enjoyed this instructable, still busy with it, but thanks LadyYada for this instructable.
what is he using to hold the pcb? id love to know what type of vice that is
She* <br>Not certain on the exact name, but i have one very similar i bought at a electronics store called a PCB vise...
Hi, great project. Does anyone by any chance know the name of this components in Spanish?<br>Thanks a lot.
Products still tend to be sold under their english names... however the part numbers should at least be usable..
If I wanted 2 parallel banks of 2 AA's to increase charger time, would your circuit work still?
if you have 2 sets of 2 AA's in series, and these sets in paralell (i.e. so the voltage is still 3V ) then yes it will work, you can also use AA or C or D size batteries.. <br> <br>:)
This is one of the best idea I have never seen &quot;IF&quot; I saw this design 5 years ago. <br> <br>No disrespect at all, but, I had my first 2G iPhone back to 2007 and I already bought this product in the market 5 years ago for my iPhone. <br> <br>You didn't mention this is the original design, but if there is any product similar to yours. Why pay more for your product? All the big brand such as GP. Their retails price is even lower than yours. <br> <br>Good luck mate.

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