CIRCUITS
1. 2 milliseconds on-time
1.0 milliseconds off-time
7. 1 milliseconds on-time
27. 8 milliseconds off-time
1. 2 milliseconds on-time
1.0 milliseconds off-time
7. 1 milliseconds on-time
A B
Fig. A: On/off infrared blink sequence for JVC brand
TV remote controls.
FFigig..BA::Pull wire-wrap wire through the cap’s
fabric to connect the switch on top.
How TV-B-Gone Works
TV remote controls all work the same way: by
transmitting coded patterns of 940nm wavelength
infrared to the television’s remote control receiver,
somewhat like sending Morse code with a flashlight.
The receiver watches for blinking IR, and when it
sees patterns it recognizes, performs the corresponding functions on the TV. To avoid accidental
triggering by reflected light in the room, receivers
only respond to IR light that pulses at a specific
carrier frequency.
For our TV-B-Gone, we don’t care about couch-surfing functionality; all we need is the code for
turning a TV off. (Because remotes have just one
on/off button, this is the same as the code to turn
it on, and the TV’s current state determines which
new state to toggle to.)
For example, to turn off a JVC TV, you blink the
pattern shown in Figure A using a carrier frequency
of 54kHz. The entire sequence lasts only a tiny fraction of a second, so there’s no perceivable delay.
Different manufacturers’ IR standards vary, but
they all use rapid blinking of an even faster carrier
frequency. TV-B-Gone transmits the on/off button
codes for most TVs, one right after the other. So it
works like other remotes, but with just one button.
1. Assemble the kit.
First I built the TV-B-Gone kit itself. I already knew
how to do this, but you can follow the excellent
instructions at ladyada.net/make/tvbgone.
170 Make: Volume 13
2. Install the switch.
Take out the batteries and unsolder the battery
leads from the board. Then bend the 4 legs of the
tactile switch apart so they’re flat, and hot-glue the
switch to the button on top of the cap (Figure B).
Use needlenose pliers to push some of the wire-wrap wire through the hat fabric near the button.
Pull enough wire through on the underside of the
hat to reach the end of the visor. Repeat using a
second piece of wire, then solder the wires to 2
of the switch’s legs on the same side, clip off the
other 2 legs, and cover the soldered joints with
5" heat-shrink tubing.
If you use a lighter, be careful not to place the
tubing (or the hat) directly in the flame. Hold the
flame just above the tubing and move it around
slowly until it’s fully shrunk.
Use a needle and thread to sew the 2 wires to the
inside of the hat. I used 5 loops for each, tying them
off with a square knot (Figure C). Alternatively, you
can also use hot glue.
Position the assembled TV-B-Gone at the edge of
the visor of the hat, with the IR emitters just inside
the brim, pointing outward. Cut the wires from the
hat-top switch so they extend just past the switch
button on the circuit board (Figure D).
3. Install the battery pack.
Center the battery pack under the cap’s dome with
its 2 wires facing forward, toward the visor. Hot-glue
the battery pack in place, then sew (or hot-glue) its
wires to follow the same paths as the switch wires.
