Possible to have variable resistor controlled via current or voltage?

[excetara2]

I want to control a variable resistor externally. I was wondering if this was possible. I was going to have labVIEW software that controlled via the output of the daq a variable resistor. So I was wondering if it was possible to externally control. Any ideas would be awesome.

Jeff

 

[jpanhalt]

Look up digital potentiometers. John

 

[HS3]

I want to control a variable resistor externally. I was wondering if this was possible. I was going to have labVIEW software that controlled via the output of the daq a variable resistor. So I was wondering if it was possible to externally control. Any ideas would be awesome.

Yes, it is called a Transistor and there are many types, including FETs.

You need to be more specific. Variable resistor? For what ranges of voltages, currents, etc? What application? It may well be there are ready-made components you can use or you may need to design your own solution.

 

[excetara2]

Biologically implementing a single cell model. I was going to have the resistors controlled by the output of a DAQ. I could change range of voltages. I was going to use 0 to 1 volt. The computer is going to control the differential equations. I was going to have the DAQ output a voltage corresponding that I wanted to control the resistance to model the voltage across the membrane. I will probably have to tweak the output of the DAQ. Let me know if you have any tips.

 

[crutschow]

Seems like you could eliminate the DAQ and just use a digital potentiometer. What is the resistance range you need?

 

[excetara2]

It has to be externally controlled. Resistance range is yet to be determined. I want it to model the spiking of a cell so not sure. It depends on all other resistances. I would say 20-500. I am not sure yet. It can't be controlled by hand.

 

[crutschow]

Analog Devices sells numerous digitally controlled resistors. For example, the AD5254 has 256 steps (8-bits) and is available in a 1K ohm version. If that resolution is adequate, it might do what you want.