Author Mazi Hosseini describes a simple, low-cost, voltage-controlled current source using two op amps that provides a good range of current and maximum load.

Engineering labs are usually equipped with various power supplies, voltmeters, function generators, and oscilloscopes. One piece of equipment missing from many such labs, however, is a current source.

This Design Idea mates a precision current source IC with precision difference amp chips to create a programmable current source or sink. The resistor-programmable current source/sink in Figure 1 ...

A current source provides electrical energy with a constant current. The implication is that if the resistance of the load changes the current source will vary the voltage to compensate.

You can achieve accurate resistance-temperature-detector sensor measurements without having to resort to using a precision current source.