IR Transmitter & the AC Switch

Control household devices with littleBits!

Screen Shot 2014-11-22 at 10.07.31 AM

The IR transmitter and the AC switch make a powerful pair that lets you control your household power outlets with your littleBits circuits. Watch our video tutorial to learn how to set them up.

How The IR Transmitter Controls the AC Switch:

The IR transmitter controls the AC switch using a beam of infrared light. This IR signal is sent from the little IR LED on the transmitter and is received by the sensor on the AC Switch (the thing that looks like an eye on the end of the white wire).


closeup_IR_transmitter_NO_callouts clouseup_AC_switch_with_callouts


Infrared light isn’t visible to the human eye, but it still behaves a lot like visible light, so in order for the signal to travel from the transmitter to the switch, you will need to have a direct line of sight between the transmitter and the sensor.

 The transmitter sends out the IR signal in a 150 degree cone (see image below), so the line of sight from the transmitter is quite wide. In situations with a lot of IR interference the transmitter may only have a range of 15 feet, but under most conditions further distances will work just fine. The signal is strongest about 30 degrees out from the center, so if you are having trouble getting the range you want, try adjusting the position sensor.




How to Pair Your IR Transmitter With Your AC Switch:

The AC Switch can be controlled by a lot of different IR signals–we will need to pair it with the IR transmitter so it learns the correct signal. Before you begin, make sure that at least one of the little switches on the IR transmitter is set to the “on” position. Each little switch represents a channel broadcasted by the IR transmitter. Scroll down to learn more about how the channels work in the section called “Who are you Calling a Dipswitch?”.

To start the pairing process, plug in the AC Switch and wait for the LED on it to blink red (if the switch is already plugged in, you can just press the white button to put it in pairing mode). Once it is blinking, trigger your IR transmitter (with a button or any similar input). The IR Transmitter will now send its signal to the sensor on the AC Switch. When the AC Switch blinks rapidly and then turns off, you know the two have been paired.

Now you can plug your appliance into the AC switch. Make sure that you turn the appliance on when you plug it in.

 NOTE: You can control more than one AC Switch with a single transmitter. All you need to do is pair the transmitter with each one of the switches.


Channels: Controlling Multiple Switches:

The IR Transmitter can send out four different signals, so you can control four different groups of AC Switches separately. For example, you could turn some of the switches on, but not others, then turn the other ones on later. You can choose which channel you would like to send out by varying the voltage going into the IR Transmitter module.

Placing a number module before the IR transmitter will help you know which voltage you are sending into the transmitter. When the number module is set to value mode, the channels correspond as follows:

  • 10 – 25 will trigger channel 1

  • 30 – 45 will trigger channel 2

  • 50 – 65 will trigger channel 3

  • 70 – 85 will trigger channel 4

  • 90 – 99 will trigger all 4 channels at once


To pair an AC Switch with a particular channel, use the setup procedure above using your chosen channel.


Who Are You Calling A DIP switch?

You can also control which channel the IR Transmitter is sending out by using the DIP switches on the top of the module.




Each switch corresponds to a channel. If the switch is up (or ON) the transmitter can broadcast that channel. If the switch is down, that channel is blocked from transmission. If you only want to send channel 1, you can turn off the other channels by flipping their switches down. Now if you send the transmitter a full 5 volts, only channel 1 will be sent (because the others will be blocked).



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