How to build a USB IR blaster

My biggest gripe with using Windows as the OS for the VCR Project is the fact that my SIIG MCE IR receiver requires an infrared “signal” to activate before I’m able to initialize the service that controls its commands. As it stands, in order to use an IR remote with the VCR, I must boot the system, wait for Windows to start, press a button on the remote control, restart the AlternateMCEIR service, then load Kodi. EventGhost can handle almost all of that–except the button press. What I need is a way to hit the IR receiver with a burst of IR light automatically, so I can eliminate any physical intervention during startup. What I need is a USB IR blaster.

The vast majority of USB IR blasters on the market are extremely expensive and of dubious quality, so after quite a bit of research, I figured out how to build my own from a handful of parts that I picked up at my local Micro Center.

Gathering supplies for your homebrew USB IR blaster

You’ll need a few ingredients and tools to build your blaster, but out the door, you should be able to build the item for around $15. The most expensive part will be the USB control board, which (at time of publication) Micro Center sells for $9.99. I’m using the Inland FT232 USB to RS232 adapter. The adapter uses the FTDI driver to emulate a serial COM port.

FT232, the heart of our USB IR blasterNow, in order to send IR signals, we will need an IR light source. You would be surprised exactly how difficult it is to find an inexpensive IR emitter off the shelf. All the units I was able to find were in the neighbourhood of $10 (or more), but then I found this:

USB IR blasters need an IR light source
Time to void some warranties!

In addition to these big necessities, you’ll also need the following:

  • 220 Ohm resistor
  • wire
  • USB micro cable
  • crimp-on header pins/jacks
  • soldering iron
  • warranty voiding tools
Obtaining the IRLED

Assuming you found a cheap remote control (check thrift stores; they’ll usually have about 12.3 million of them in stock), you’ll need to crack open the casing to expose the PCB inside. Soldered onto the PCB will be your holy grail LED. Hopefully, there will be a diagram to illustrate the polarity of the LED (saving time and effort later). Considering the light emitted is invisible, it will be rather hard to test for the correct polarity later, so go ahead and mark the leads while the diode is still soldered into the PCB.

USB IR blaster needs IR to workUse your soldering iron to melt the attachment points and carefully remove the LED from the remote control’s board.

Depending on your setup, you may need to run wire from the FT232 to the LED. I’m going to assume you know how to crimp wire and all that, so I’m not going to describe that process. I have a short length of wire running from the FT232 to the IRLED so that it will easily sit next to the receiver plugged into a front USB port.

No matter how you have the leads connected to the FT232, you’ll want the anode plugged into the DTR jack and the cathode is plugged into the TXD jack. Make sure that you wire the 220 Ohm resistor into one of the leads so you don’t end up “popping” the LED by over-volting.

Plug the FT232 into an available USB port and install the FTDI driver according to their instructions. In Windows, the device should appear as “USB Serial Port” in the Device Manager. Now that we’re assembled and installed, we can send IR signals to any device!

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