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Most infrared remote controls operate at 40 khz. This circuit transmits a simple 40 khz squarewave. If done properly, it will effectively disable common household infrared remote controls.

Construction Notes:

  1. Multiple IR LEDs may be connected in parallel for more power output. This may be necessary for expensive Japanese equipment.
  2. Adjust the 10kΩ resistor until the frequency is just right and everything works. Alternatively, a frequency counter may be used. Then again, if you know what a frequency counter is and know how to use one, you can probably build this from a crystal and a gate.
  3. For maximum effectiveness, spend a lot of money on a high-capacity lithium battery, replace the push button switch with a toggle switch, and hide in a clever place.

                                       |                       
                                       |/|
             +---------+------------+--| |------/\/\----+
             |      +--+            |  |\|    50Ω 1/4W  |
             |      |  \            |  |                |
             |      +->/ 10kΩ 1/4W  |  IR LED           |
             \         \ Adjustable |                   |
 100kΩ 1/4W  /  2N4403 /            |                   |
             \      ---+            |          +--------+
             /    |/_  |            |      1μF |        |
             |   |/    |            |       + ---   + -----
             +---| PNP |            /         /-\      ---
             |   |\    |          |/ 2N4401    | 4.5V -----
             \     \---|---/\/\---|   NPN      |       ---
 150kΩ 1/4W  /         | 1kΩ 1/4W |\           |        |  
             \         |           _\|         |        |
             /        ---           |          |        |
             |        --- 10nF      |          |   o    |
             |         |            |          |  ---   |
             +---------+------------+----------+--- ----+
                                                         
                                              

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