So you get in from a long day, all you want to do is sit down and watch that new tv show / movie that you downloaded last night, so you pick up your mediacenter's wireless keyboard and hit space to wake it, nothing, you hit it again, still nothing. It's dead. Oh joy, now you need to wait 5 hours for those batteries to charge, wouldn't it be grate if you could charge it in 20 seconds and be done with it? yes? well now you can.
This is a very simple mod that will add a super capacitor into your wireless keyboard (i chose to leave the battery compartment in so i can use batteries if i want), there is a few things to consider before you do this mod, firstley if you keyboard is very power hungry this may not be for you (but don't let that put you off, it can never hurt trying just hooking one to the battery contacts for awhile) and if you use your keyboard allot it may have the same effect as if it was very power hungry.
A note on safety:
Remember these capacitors hold allot of charge, because of the low voltage you are unlikely to get a shock of it unless you lick it (I know it's tempting, but try to avoid it) but nevertheless, be careful and always discharge the capacitor before working on it.
Also it should be noted that super capacitors don't like being charged at more than the rated voltage, this is why we charge it with a voltage regulator.
Step 1: Gather Materials
What you will need:
-Super Capacitor (I used a 10F one) (I got it here )
-Some sort of socket (I used a phono one)
-A plug to fit your socket
-Wire (I used some scavenged from some cat5e cable)
-A 2.5v regulator (TS1084CZ-2.5) (I got it here )
-2x Small Capacitors (Optional) (I used 2 10uF ones)
-A small piece of stripboard / protoboard / PCB
Step 2: Crack Open That Keyboard
After you have tested that your keyboard will run sucessfully of a super capacitor you are ready to start, grab a screwdriver and that keyboard and get started!
Step 3: Decide Where to Put the Super Capacitor
Find a good place to put the super capacitor, you could put it in the battery compartment, but then you can never use battery's again. I was originally going to put the super capacitor at the top of the keyboard, but the keys and PCB where in my way, but i found it fits nicely in the parmrest.
Step 4: Install Your Super Capacitor
Start by dremeling off any unnecessary plastic around where your super capacitor is going to go, then solder a different color wire to each lead of the capacitor, insulate with tape or heatshrink if needed ( i used a pice of plastic in the keyboard to separate the leads so this wasn't nessery). Now hot glue the super capacitor into place and root the cable coming off it to the keyboards PCB (or to the battery holder) and solder the negative cable to the appropriate point on the board.
Step 5: Add Charge Socket and Super Capacitor Isolator Switch
Grab your drill and the bits required to drill the hole for you charging port and switch and drill the holes, install your charging port.
Now how you install the switch depends on what one you have, if you have one which the toggle can go through the plastic of the keyboard and still be moveable grate, mount it on the underside of the hole (inside the case). If you have a small switch (like me) solder 2 lengths of wire to it, now carefully thread the wires through the hole, turn the keyboard over and inject liberal amounts of hot glue into the hole
Step 6: Connect It All Up
This is very simple, just connect it up according to this diagram. (i know no one is gonna need this, but here it is anyway)
Step 7: Put It Back Together
Start by tapeing the the excess wires out of the way of all the keyboard buttons, make sure all electrical joints are insulated and then reassemble the keyboard.
Step 8: The Charger
Now unless what you charging from is the same voltage that the super capacitor is rated for (typically 2.5v) you will need to have a step down regulator to safely charge your keyboard, you could build this into the keyboard, but as i am going to convert my mouse at the weekend i needed it to be separate. anyways this is a very simple circit (Note the 2 small caps are not essential, but they grantee a smooth output)
Step 9: Your Done!
Now you never need to wait hours for batteries to charge.
Enjoy your fast charging Super Capacitor keyboard :-).