chamilackjm,
Audioguru says "The PNP transistor in the transmitter is
drawn upside-down". I questioned the orientation of this
transistor when I wired up the circuit. Seems like the
emitter should be the other way around in order to forward
bias the diode.
I tried it both ways and the signal going to the diode was
exactly the same and the IR reciever didn't care either.
Maybe the transistor is in Saturation Mode one way and Forward
Active Mode the other way. I'm not sure, maybe audiogugu can
wade in on this.