Looking for a part that will vary resistance levels

Is there an electronic part that will act as a resistor, supplying an amount of resistance across two terminals that vary with respect to a changing amount of electricity passing though another two terminals? Or, does what I am trying to describe have to be made as a circuit of more than one electronic part? Where can I learn about the easiest way to obtain or build a device that will perform this function?

You can use an ldr and led connected together with black shrink tubing or you can do something like this:
**broken link removed**

The nearest simple part that can do this is a JUGFET but the problem is it isn't very consistant.

You haven't given much information, what's the voltage controlled resistor going to be used for?

I started designing a voltage controlled resitor for a programmable load that was going to be used in a project at work but it got cancelled. My idea was to use a MOSFET, current sense resistor, potential divider and analogue multiplier IC (connected as a divider) in a feedback loop. Unfortunately I only got as far as the block diagram so I can't post the schematic which probably would've been too complicated for what you need.

Hero999 said:

...what's the voltage controlled resistor going to be used for?

Click to expand...

I am still researching the value of the max. and min. voltage level that I want to drop between ground on a USB plug and a pin on one of Cypress’ microchips at **broken link removed**. I would like to experiment with voltage levels - that will determine the varying resistance levels, that are about the same as those produced by a speaker on a cassette recorder that plays the types of cassettes at http://en.wikipedia.org/wiki/Compact_cassette.

I don’t want to make this sound confusing – just the name of the part or the location of a schematic would be helpful. Though, I would appreciate specific help.

Sounds like a voltage controlled resistor. Try this link.
https://www.electro-tech-online.com/custompdfs/2008/10/Vishay-Silcnx_FET_VoltCntrlRES_AN105.pdf

What about a log potentiometer?

I remember someone saying something about a potentiometer. Is a logarithmic potentiometer just like a regular potentiometer except that the resistance level is tapered? I can’t figure out how to use a potentiometer to connect input and output pins – for a total of four pins, in two different circuits having two different voltage supplies. Could you provide or describe a schematic for this option?

a FET can also be used as a VCR.ofcourse dont know whetehr it suits you aplication or not.