A few years ago, I bought an FM transmitter that ran on batteries and plugs into the headphone port of an mp3 player to play through the car stereo, It had been rattling around in a drawer for a few years, Until I came up with this.
It still rattles around in the drawer, but I get more use out of it. Repurposed in the opposite direction by transmitting from my PC and or TV to an mp3 player with an FM tuner.
I can wander about and still hear my music or movies without disturbing others.
Great for late nights in the laboratory!
Step 1: What you will need...
1. Maxell FMT-1 - FM transmitter
2. USB cord (Will be cutting)
1. Soldering Iron
3. Wire Clippers
4. Wire Strippers (I sometimes use cigarette lighter)
5. Some form of Glue ( I used hot glue)
6. Phillips head Screw Driver
7. Exacto/Box Knife or Hobby Knife or other form of cutting tool.
Step 2: Let's get down to business...
Okay, first thing, get you soldering iron set and warming up.
Now, the next thing to tackle will be the USB cord.
For this you will need the wire cutters and strippers
Find the male end and cut the cord about 3 inches from it.
Once you have it cut - remove the wire casing from the whole 3" of USB cord - take your hobby knife and cut the plastic/rubber from the plug itself as well, when you're done you should just have a metal USB plug with 4 wires protruding from the end.
( Red,Black, Green and Yellow )
Cut the green and yellow wires completely off, those are for USB data and are not needed.
Strip the tips of the red and black wires, expose enough for soldering.
Step 3: The Transmitter
Open the battery compartment, remove the two screws holding it in and pull it out carefully.
Next, remove all the battery terminals from the plastic, they should slide up out of the slots they're in. (Mine came out easy after applying some heat to them with the soldering iron).
Once you have that done, Unsolder the wire from the negative terminal and desolder the diode from the positive terminal.(Be sure to keep the diode attached to the positive wire.)
Replace the battery box and begin cutting out a slot for the usb.
You will have to cut part of the battery case and the outer case of the transmitter and it helps to have the battery box in while doing this. (Pictures)
Step 4: Solder & Glue
Start by tinning (applying solder to) all of the exposed wires and the diode on the transmitter and USB Cord.
Once you have everything tinned, begin soldering the negative to negative and do the same with the Positive USB wire and the diode on the transmitter.
Soldering all done? Good.
Now adjust the usb plug so that it protrudes far enough from the transmitter and plugs in properly to an extension cord or usb port of a PC/TV. Once you have it properly in place glue it in and wait for it to dry.
Replace your battery box cover and enjoy the Semi-Freedom!