Ultra TV-B-Gone

Step 5 Complete the circuit

If you are looking at the flat side of a 2N3904 with the pins down the pins are called Emitter, Base, and Collector from left to right. Attach the Collector and the LED- connection from the TV-B-Gone PCB to the negative side of the LED array. Then connect the Base to the LED+ wire. Next connect the emitter to ground on the circuit board.

Now wire the positive side of the LED array to the 9V supply. Finally connect the ground and 9V wires from the PCB to the 9v Battery clip. Attach the LED array and PCB to the battery clip. You can use anything from around, duct tape will work nicely. I had some double stick foam so I used that. The End.

Comments

[putty1cat]

My tv b gone is different but I went ahead and tried to mod it. I get nothing out of it. I am clueless. Can someone brainy, please, have a look and tell me what I've done wrong? This is only my second soldering project. The chip is the SE02 500 A3A3 if that is any help.

[d60Dave]

Hi,

Perhaps my TV B Gone unit is different but as standard the IR LED positive terminal is connected to the positive of the battery and it appears to be the negative side of the IR LED that is switched to turn it on and off.

If as you suggest the positive side of the IR LED is connected to the base of a 2N3904 (npn transisotor) with the emitter connected to 0V there willl be 9V across the base-emitter junction. It will therefore be on all the time or at least until it blows which shoudn't take long as a typical npn can only support about 0.7V (one diode drop) across the base-emitter.

Am I missing something??

Dave.

[Pepsiman]

(removed by author or community request)

[DarkStar851]

Err... it's not a lamp. x] TV-B-Gone is basically a Television Remote, it just has more Infared Lights in it. Infared can only be seen by Cameras or Infared Sensors, :]

[maestro8]

Using a transistor as a switch in the manner you are suggesting is quite inefficient. The base-emitter junction saturates at <0.85V (from 3904 spec sheet), where you're applying ~3V. This will cause the transistor to draw excessive amounts of current, shortening the life of the button cell. The simplest fix would be to insert a 1-2kOhm resistor inbetween the LED+ wire and the base of the 3904. A 1/10 watt resistor will do, and it's small enough as to not effect your configuration of components.