Introduction: Portable 9V to 5V Battery

Step 1: Checklist, Parts and Tools.


- 9V battery (duh)
- 9V battery clip (duh again)
- 5V regulator ( L7805 ) sparkfun $0.85
- a piece of proto board
- 2x 1uF ceramic disk capacitor (this isnt really that exact, use about this value if you do not have it)
- an aluminium heat dispenser (not sure if its really needed, i added it just in case)
- some heatshrink if you mess something up like me (if you do it right, unlike me, you wont need it)

- a green status led (+150ish ohm resistor)
- a switch


- soldering iron
- dremel
- needle nosed pliers
- third hand (not really needed, but makes it all alot easyer)
- multi-meter (or osciloscope if ur rich...)
- hot glue gun (or just some glue sticks and a candle, if you broke your gun like i did)

there's also a schematic here.

Step 2: Prep It Up!

first up, if you do not have the aluminium heat dispenser, go look in some old electronics (radio's, TV, CRT monitors, old PC's, nearly anything bigger than your Iphone)
if you still dont have it, skip this step, i dont think it really matters.
please, if you have experiences without one and it doesnt matter, please send me a message!

now, to work my minion!

take the regulator, and put some heat paste on the backside of it, this will heat transfer from the regulator to the aluminium.
again, i dont really think its that important, and if you have experience in using this without the paste, contact me please.

then, screw on the regulator tight, if you used to much paste, it will come out so this is a good point to see if you used to much, for future use.

becouse my screw came out a bit to far, i drilled a small hole at the top of the proto board.

take the screwdriver, and bend the pins of the regulator in a 90degree angle, so that they stick out the back, but do not touch the aluminium.
then, insert the regulator and solder it.
dont hold your iron against it for too long, you can burn this thing!
just solder one pin within 5 seconds, then carefully feel how hot the regulator/aluminium is. as soon as its only slightly noticable that its a bit warm, then you can solder the next pin.

Step 3: Frisbee Anyone?

now, for the capacitors.
first, work the kinks out of the legs (sounds like a cheap horror movie to me!)
and then put them in next to the regulator

flip the board over and solder the capacitors. bend the pin closest to the regulator towards the outer pins, and solder them together.
then, bend the lowest pin of the capacitor to eachother, and solder them. then make a solder bridge to the middle pin of the regulator.
(picture is more clear probably)

Step 4: Optional: Led

i choose to add a led, becouse i wanted to make sure it worked, before i went using it.
of course, it will work without it, but it is functionall, looks good, and doesnt drain alot of power (really, i think with a full alkaline battery, it will keep light for about a month!)

so, i placed it to the left of the regulator, added a resistor, and soldered them to the 5V and ground pin of the regulator.
but, i placed the led the wrong way around, and had to use some heatshrinking tube to cover it up.
the pictures say it all ;)

Step 5: Connect the Battery

take the battery clip, and solder some wires to them if theyr not already in place, length isnt that important as we cut them to size later.
solder them to the right places on the regulator.
double check these connections!

then, test the device by putting in a fresh battery.
if the led lights up, congratulations!
if it doesnt, dont worry! take out the battery, and check every connection.
first, the led, is it inserted the right way?
then, take your multimeter, and measure the middle, and the two outer pins of the regulator.
one should say something from 7.5~9V, and the other +-5V

if it doesnt, go check everything, use your multimeter in a resistance test, and check if all solder bridges are OK, no cables are broken on the inside (i've had this!) and all that.

if all else fails, you probably burned your regulator, replace it and then it should work

Step 6: Making It Compact

first off, i forgot to put the 2 output wires in.
so, i had to remove some hot glue with my soldering iron, and install them later.
better to place them before (duh)
the one should go to ground, the middle pin of the regulator.
and the other to the (if looked from above) right pin of the regulator. (or left, if you look from the bottom)

then, to protect the circuit as much as possible i covered the bottom with hot glue, just a small layer, to cover up everything.

then, shorten the wired of the battery clip, so you can place the clip roughly like mine.

after that, just ad some hot glue to fix the clip.
test if the battery fits, if not, heat the glue, and reposition.

when its in a good position, add more glue so it will hold the force used to place the battery.
specially cover up the back really good, and make it go all the way around to the protoboard, dont go cheap on glue here!!!

Step 7: Finished!

this is the finished product.

i made this becouse i had a portable speaker set, but it required 4 AAA batterys, and i thought a 9V battery would be much easyer to use.
but, it can be used for nearly anything, if you ad an USB socket, you can charge your USB devices with it, mintyboost style.
or use it with your homemade electronics.
the list is virtually endless!

if you have any comments, dont be afraid to post 'm.

thanks for reading, and goodluck building it.