You can use 390Ω and 100Ω resistors, both standard values, in series to create 490Ω resistance.
---/\/\/\390Ω/\/\/\---/\/\/\100Ω/\/\/\--- = 490Ω
This line is used to supply initial power to the field coils, then once the generator begins producing current it is self-exciting. At that point the regulator supplies near 1/2 the regulated output to the light green/red wire, which keeps the indicator lamp off.
If the generator output voltage falls below its proper value the voltage delivered to the lg/rd wire falls, turning the indicator on...
- 2003 GT, UPR X, FRPP 24lb/h, Magnaflow, PP 70mm TB & plenum,
Delta Force tuned, Steeda UDPs, Ralco flywheel,
RAM HDX clutch, 3.73s, 262 rwHP/305 lb-ft.
New ride (7/1/2013) 1998 Mercedes SL500-5.0L 32V VVT 326/347 HP/tq
Engineering is, at its base, making what you want from what you have.
At its extreme it is making what you want from what you can get.