Have an old television lying around and a weekend to spare? Turn it into an awesome portable amplifier for your phone, computer, or guitar! All the parts you need are contained in the television itself.
Check out this instructional video before you get started!
Step 1: The Parts
You will need:
1x CRT television (the old, bulky type... the smaller the better)
1x box (I got my plastic box from a thrift store for $0.80)
1x propane blowtorch (for removing components)
Various wires or tape
Any other standard tools that will help you through the following steps
CRT televisions contain a flyback transformer (the suction cup) that can hold a LETHAL charge. Please follow the steps to discharge the transformer before you touch any components inside the television. If you are unclear about any of the steps, please do your own research because you are not ready for this project. I take no responsibility for any injury that occurs during the building of this circuit.
With that out of the way, let's proceed to taking apart the television.
Step 2: Disassemble the TV
Start by removing the screws on the back of your television. Once they are removed, carefully pull the back off of the television.
Do NOT touch any of the internal circuitry just yet. Refer to the pictures if you need further guidance.
Attach an alligator jumper to the metal strand of wire that is stretched across the back of the tube. Attach the other end of this jumper to the metal tip of an insulated screwdriver.
Next, locate the suction cup on the back of the tube. Push the screwdriver up and under the suction cup until it pops out. Then touch the screwdriver to the metal "anode" pin in the center of the suction cup. The flyback transformer is now discharged.
Just to be safe, touch the screwdriver to the back of the heating element circuit board on the very back of the tube. Now it is save to carefully pull this board off the back of the tube.
Start disconnecting any wires keeping the main board attached to the picture tube. The goal is to remove this board completely.
Step 3: Locate the Audio Amplifier IC
Now you need to do a bit of detective work. You are looking for the audio amplifier chip on your television board. Here are some tips to help you find it:
1. It will most likely not be a long 24+ pin flat chip. Those are usually for driving the display.
2. It might be vertically aligned and attached to a heatsink, having anywhere from 7-15 pins.
3. It might be a small 8-pin dip chip like mine was.
4. It will most likely have electrolytic capacitors around it, because audio circuits usually involve these capacitors.
5. The code on the chip will most likely start with KA, LA, or TDA and have three to four numbers following the letters.
Once you think you found it, google the datasheet and see if you were correct. Remember, you are looking for an audio amplifier. Next, locate the schematic on the datasheet. This is the circuit that you are going to build. Write down the parts that are contained in the circuit. All of these parts can be found on your television board.
Tip: Don't be afraid to approximate! If you need a 330 ohm resistor, and all you can find is a 220 ohm resistor, use that instead. It won't make a significant difference.
Step 4: Removing the Components
Take your blow torch and circuit board outside. Locate your IC chip and either grip it with some pliers or wedge a screwdriver underneath it. Apply the blowtorch to the underside of the board where the leads of the IC are located. Hold it about 4 inches away for six to eight seconds. Them wiggle your screwdriver or pliers until the chip comes out. Do this for all the components that you need to remove.
Don't hold the blowtorch on the board for too long! It will catch on fire and produce toxic smoke.
Step 5: Build the Circuit!
Not much to say here, just put your circuit together! Use whatever audio jacks that were on your television to use as the audio input. Be sure to choose a power supply within the voltage range of your chip (check the datasheet). I was able to use a 9v battery. I also added an LED, a switch, and I used the speaker from my television.
Step 6: Rock It Out!
Flip the switch, plug in your music, and hit the streets with your portable audio amplifier. My favorite thing is to re-purpose old electronics into new, interesting gadgets. Something that you would throw onto your front lawn on garbage day is now something useful that you can use for entertainment just about anywhere. Share with me your take on this project and what you would do differently.
Thanks for viewing and happy building!