12v to 3v

[Terryc]

Maxamillion wrote:

Can somebody please give me assistance with a circuit to power from 12v a
variable 1.5 to 3v circuit. Presently the small fan is powered by 2 x D
cells and runs for around 6 hours. I would like to have a potentiometer
that goes from 1.5 to 3.0v.
The fan will be finally powered from a 12v SLA battery charged from a solar
panel.

In that case, look at replacing the fan with a 12 volt version as they
come in all sorts of sizes.

Otherwise, loo at a 7805 regulator circuit, then burn up the excess
voltage in a resistor. Simple calc.