voltage to resistance convertor?

If I have a source of variable voltage ( a sweep generator for example),
is there any way to create a source of varying resistance in proportion to
the voltage?

About the only way I can think of off the top of my head is a light/LDR
combination, but I doubt that would be very efficient or accurate.

Anyone have any better ideas? Preferably simpler ones, even if it is
slightly less accurate. Or maybe someone knows of a resistance sweep
generator...

Thanks
Andrew Howard


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