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what are you missing? load impedance,
you wont get a load stable voltage even if the divider or series resistor is fed from a regulated 18v supply, the higher the divider network impedances the more it will drop under load,
using high wattage resistors of lower impedance should make it less load sensitive but it also loads the supply far more wasting energy as heat in the divider and supply,
if your load is dynamic or anything but very low current / high load impedance you would be much better off using a 3 terminal regulator,

try a 7815 or at a push a 7812 with a resistor between the middle leg and ground to pull the voltage up to where you want it under load,

good luck.

[QUOTE="bob85, post: 151814, member: 18"] what are you missing? load impedance, you wont get a load stable voltage even if the divider or series resistor is fed from a regulated 18v supply, the higher the divider network impedances the more it will drop under load, using high wattage resistors of lower impedance should make it less load sensitive but it also loads the supply far more wasting energy as heat in the divider and supply, if your load is dynamic or anything but very low current / high load impedance you would be much better off using a 3 terminal regulator, try a 7815 or at a push a 7812 with a resistor between the middle leg and ground to pull the voltage up to where you want it under load, good luck. [/QUOTE]

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