NEW PROTOTYPE: USB Infrared Toy v2

Use a remote control with your computer, view infrared signals on a logic analyzer, or capture and replay remote control buttons. USB Infrared Toy v2 has higher-power infrared transmitter and several new features.

Read the full design documentation.

  • NEW: 100mA constant current IR transmitter with improved range
  • NEW: Infrared frequency measurement
  • NEW: Pin breakout area
  • Infrared remote control decoder (RC5)
  • Infrared signal logic analyzer
  • Capture and replay infrared signals
  • USB connection
  • USB bootloader for easy updates
  • Supported in WinLIRC
  • Open source (CC-BY-SA)

USB Infrared Toy v2.0 has arrived. Read the full design documentation.

Get one for $19.50.


There’s lots of interesting infrared projects on the web. Serial port infrared PC remote control decoders have been popular for years, Ian published a USB version at Hack a Day. The TV-B-Gone is a popular kit that turns most TVs off by transmitting POWER codes with infrared LEDs. The IR Toy combines all these projects into an upgradable USB dongle, with some extra functions, like a simple logic analyzer that visualizes remote control signals.

IR Toy v2 has three updates that were not in the original hardware:

  • Transmit range is increased by using a 100mA constant current driver circuit
  • Infrared frequency measurement helps to identify remote control protocols, and to clone remotes with odd frequencies
  • Extra pins and infrared signals are brought to a breakout area. Extent the IR Toy with extra receivers, transmitters, and other parts

The added cost of new parts, and the increased cost of PIC 18F2550 chips, made v2 about $2 more expensive than v1.

IR Toy v2 overview:

  1. USB MINI-B connector
  2. Indicator LED, blinks on receive and indicates other functions depending on mode
  3. Infrared transmitter LED
  4. Infrared demodulator
  5. Infrared frequency detector
  6. PIC programming header pins
  7. Serial UART pins, can be used as a USB->serial converter
  8. Access to the infrared transmitter and demodulator signals
  9. Unused pins, including +5volt supply from USB

Infrared frequency detector

While 36-38kHz is the most common frequency for remote controls, some operate at 56kHz, or even more exotic frequencies. The new infrared frequency detector (RX2) measures raw infrared signals.

The extra sensor data can be used to measure the carrier frequency. It might even be possible to record signals in frequency ranges that don’t work with the 38kHz demodulator.

Infrared transmitter

IR Toy v2 uses a new constant current driver circuit to give the transmitter LED more power. It’s way better than the single resistor in the older IR Toy designs. The LEDs get a constant 100mA no matter the supply voltage. The USB power supply varies between 4.5 and 5.5volts, the new design ensures maximum current at all voltages.

More importantly, we don’t rely on a huge current limiting resistor. Previous designs burned excess current in the typical LED current limiting resistor circuit. The resistor needs a minimum power rating of 0.34watts for 100mA IR LED, way out of the range of common surface mount resistors (<0.125watts). The constant current driver doesn’t rely on the current limiting resistor nearly as much. High currents are possible using standard SMD parts, but just in case we used a beefy 1206 resistor.

Breakout area

Unused pins and the main IR signals are brought to a breakout area. Digital and analog pins are available for experimenting.


Get IR Toy v2 for $19.50 at Seeed Studio. Worldwide shipping is only $2.85 more.

Join the Conversation


  1. Just placed my order. I’ve been wanting one of these for a while but have been waiting for v2. The improvements in v2 look like they justify the wait.

  2. It looks pretty well. I’m glad you found the 2 diode current source useful and decided to implement it. Good Job!

    1. Thanks for commenting. I couldn’t find our emails for proper credit. I added it to the wiki article.

      1. ?

        Being an early adopter of the USB IR Toy, I originally suggested the constant current source on Mar 1, 2010 in a topic titled “emitter follower” based on San Bergmans’ circuit, and provided resistor values on April 22.

        I have no particular issue with the details, it’s just a little strange seeing someone else take credit for an idea that I pushed for over a year.

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