I noticed in the diagram for building a serial IR blaster, a 3300 Ohm Resistor is necessary along with the LED, etc...

I have a few of the Phono Jack IR Blasters from the DTV and TiVo boxes I bought over the years. I am wondering if I can cut the end off of one and solder the two wires to the correct pins on a serial plug and have it work? Do these phono IR blasters have the right resistors and whatnot on them so the blaster doesn't try to pull too much current from the serial port and burn it out?

I am guessing it will be fine, but would like to make sure with somebody who would know or has done it.

Thanks for any answers.

You will in any case not burn the serial port, they are supposed to be designed to be short circuit proof. The resistor is there to protect the LED in the blaster.

Probably the blasters do not have the right resistor för use on the serial port. The serial port most likely have a higher voltage than the phono jacks used on the other devices.