First off, why do you want a 0.48 ohm?, it's a really strange value - next, how accurate does it have to be? - both 0.47 and 0.5 are within 5%, which is probably as good a tolerance as you're going to get.
He wants the 0.48Ω resistor for the same reason I do. I accidentally overloaded the 500 mA ammeter portion of my Micronta VOM this evening. This shunt resistor turned to crispy charcoal bits in about 3 seconds.
The closest I could find was here:
www . surplussales . com / Resistors / WireWound / WW0015-1 . html
They have a 0.47Ω 1% 0.5W
and a 0.487Ω 1% 20W (pretty darn close -- but with that power rating will be physically too big).
Our power is only .12 W so 0.5 W should be enough.
Jim C.
PS - board posting restrictions prevent me from posting proper URL. You guys will have to cut/paste and knock out all the spaces.
I'd suggest you to put in a 0.51 ohm (or two one ohm resistors in parallel) resistor in your VOM and then connect your VOM in series with a known good ammeter to check it's calibration. With a 0.51 ohmmer, you WILL get a too sensitive ammeter with your VOM. You'll have to add another resistor in parallel (PICasm suggests 8.2 ohms, try 8.2, 9.1 and 7.5 ohms) to fine-tune your VOM.