Homebrew Serial Receiver Mod Help

[Zacc D. <zac...@gm...>]

Hi!

A am building an IR receiver based on the simple circuit from
http://www.lirc.org/receivers.html
I want to drop out the '78L05, 100mA, voltage regulator' and use +5v from
USB instead, but I am not great with electronics...

Can someone please advise me of what a suitable value for R1 (pulldown
resistor) would be?
Also, would I be safe to remove D1, as there will be no risk of negative
voltage?
Would there be any other part of the Circuit that would need to change for
it to work properly?

Zacc D