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1MΩ Voltage controlled resistor?

Is there any good way to hook up a fairly wide range voltage controlled resistor circuit? So far, I've considered FETs and OTAs. I only have chopper FETs on hand and the datasheet does not list the Pinchoff Voltage. The OTA resistor setup still seems confusing to me. 

These will be used in a Voltage Controlled Oscillator circuit. 

Any ideas? Am I on the right track?

The FETs a classic, and simple method. Just use a standard Jfet. This is one of the best references I know. http://www.qsl.net/n4xy/PDFs/Semiconductor_Application_Notes/Vishay-Silcnx_FET_VoltCntrlRES_AN105.pdf

You COULD mung somehting from an LDR and an LED as well

Steve