People quickly find out that I am a dork, and their next question typically is “why do you own that old as dirt dumb phone?”. Well to be honest, I don’t like phones. After a decade of Palm Pilots and Windows CE devices, I really don’t like touch screens either (fat man fingers and a bad habit of chewing nails does not help). I also do not like that in order to get a fancy PDA with a radio you usually have to sign up for a data plan, or pay for the thing in full.
Now get off my lawn! Seriously though, I really only need my phone to do two things, make phone calls, and send SMS messages. If I had a wishlist the only other things I would like is mass storage for MP3 files, and Bluetooth. Naturally when I started my new day job I found the geek in the department and shortly there after I got asked about my basic LG flip phone.
After a few days of interrogation I jokingly snapped back with “well since you are so worried about it why don’t you give me a better phone!” With a little hinting around and a bribe of a “Swiss Roll” at lunch, I was given an old HTC phone with Windows Mobile 5.
While it is not exactly an iPhone or an Android, it is much more featured than what I had, and it has a mini SD card slot and Bluetooth! The only catch was, he could not find the charger. We did not know if the thing even worked (he had never seen the thing turned on) , or what condition the battery was in.
As a good little hacker I took it anyway, join me after the break to see me get it fired up and save a quite a bit of change in the process.
The phone in question is a Cingular 2125 (yea Cingular so its about 5-6 years old, but so is my flip phone) which is marked as HTC innovation under the battery. It seems like every page on HTC’s website includes the word “innovation”. It could go by a few other names such as Wizard 1xx and Faraday, but no matter the most useful information comes from the cingular page.
On that page it states that the phone can be charged from 5-9 volts via the mini USB port. You can charge with a standard USB cable, but if the battery is below a certain level you are required to use the wall charger. Since this phone probably has not seen a charger in at least 4 years it is safe to say the battery is flat.
I googled around for a while but never really found anything about the charger, other than their cost, One can pick up a generic USB charger for a few dollars, but I doubt that would do any good because if it would charge off of a 2 wire USB connection, it would have been charging on my computer just as well. The official charger however is 29.99 + shipping, and frankly there is no way I am paying that, and waiting a week for a phone that I don’t even know works.
Going on one of my trademarked “guess and whims” I decided to wire up a USB plug the same way a lot of Motorola phones are using a drawing found with the Adafruit minty boost discussion (and who cares if I fry it) . First up is to find a male mini USB plug, digging around I found the totally useless USB cord that came with my TI lauchpad. Using a utility knife I scored down the side of the plug slowly cutting the plastic boot, quickly removing the plug from its housing.
After removing the plastic boot, I de-soldered the 4 wires connecting to the USB plug and soldered on some long lengths of ribbon cable. Naturally one of the pins I would need was clipped off, they often do this to keep unskilled workers from making incorrect connections, but its highly freaking annoying.
In order to get around that I just used my soldering iron to scoop out the plastic around the pin, and cleaned out all the melted gunk with a knife, leaving enough metal for me to get a good solder connection. Once wires are solder on I soldered the other end to a set of pin headers so it could plug into my breadboard. Hooked it up turned it on and the phone started charging, and after a couple hours it was half charged.
I let it finish overnight on a computer USB port, and though the weekend I made a few calls, many text messages and beat “Super Mario Bothers” using a NES emulator. The battery, after all of that was sill roughly 75% of its full charge. so I know the phone works and the battery is still good at this point.
I could have left it at that, but if I ever let the battery discharge below its USB only threshold I would be doing it all over again, in order to prevent that I decided to move my 3 wires and resistor from the breadboard on to a proper power source and make my own charger.
While the breadboard was still hooked up I measured the phones current, using that setup the phone would draw just under 700ma (678 to be exact) , which is enough to screw up USB ports but low enough I have to question the intentions of HTC as they really could have dropped that.
Anyway, I rummaged around my junk box and got out an LG charger for a phone which I have never seen before, rated for 5 volts 800 milliamp, which is perfect. Now its just a matter of attaching the charger to the USB port with the 2 pins pulled down appropriately.
Cutting the cord to the LG charger I was presented with 4 wires, and since the 24(?) pin connector on the end was just held together with screws I popped it open and compared it to pinouts on google. Strangely enough red is 5 volts, green and black are ground, and yellow is an ID line (similar resistor setup I imagine except it seems backwards to what I need).
It never fails, if I look up the pinouts the wires will match logically, if I don’t look them up then its all kinds of crazy.Its just worth looking them up or probing them out, because color of wires means nothing in most situations, then you have to look them up anyway.
I clipped the green and yellow wires since I did not need them, and to prevent the ends from shorting out I took my wire clippers and tugged at the insulation a bit so the wire was back inside the insulation. Then I put a drop of liquid super glue on the ends so they would not poke back out.
Meanwhile on the USB plug I soldered a 220K ohm resistor bridging pins 2 and 4 together, and connecting the other end to ground. Finally I connected power and ground to pins 1 and 5 of the USB plug, in order to tighten things up a little I pulled on the outside jacket of the power supply cord which hides the 2 cut wires.
Now I have a proper wall wart for this phone, but it iss pretty fragile. There is really nothing holding the metal USB shield in place and there is no strain relief on the solder points. To solve the shield problem I just simply used a thin layer of gel superglue.There is a little bump in it so the boot will hold it. To solve the boot problem I pulled out my favourite little hack tool, putty epoxy. All I have to do is mark off where I don’t want the putty to go, then tape it off so it does not squish inside the plug.
If you have never used putty epoxy before its just epoxy resin and hardener in a putty form. All you have to do is kneed them together into a uniform color (mine is blue and white so it makes a purple color) and apply. You can get this stuff at different strengths with different additives, but I just use cheap “5 minute brand” from Wal-Mart. Since this stuff hardens fast you have to move quick, kneed it together to a uniform color and apply.
Once you have it blobbed on you may want to smooth the surface, since you will have fingerprints, or little spikes where the epoxy sticks to epoxy stuck to your fingers (even wearing latex gloves). The best way to do this is to wet your fingers with some plain old vegetable oil and smooth it out. It will never be 100% perfect but it will be darn good enough.
Finally before it sets up I need to trim the plug end so its not covered in rock hard gunk where it needs to be plugged in. Using a utility knife with the blade wiped down in vegetable oil simply make cuts down until you hit metal and angle away a bit so you pop the cut parts off. At this point the epoxy is starting to set hard so it will feel less like putty and more like sand, just keep making small cuts and eventually when you start seeing the tape move a bit since your now prying at the edge of it, you have gone far enough.
Now I am all set for another half decade and instead of getting grilled on “why are you using that dirt old dumb phone”, I will be getting grilled on “why are you using that dirt old smart phone … oh it plays zelda? Well OK, that’s cool then”
Sounds good to me.