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.

The easiest way to turn a simple dc/dc converter into a constant-current source is to use a sense resistor to convert the output current to a voltage and use that voltage as the feedback.

This device has four feedback loops to regulate the input current/voltage, along with the output current/voltage. The input current and voltage feedback loops can prevent overloading of solar cells.

In his video [Afroman] describes how the LM317 can be used to regulate current rather than voltage to provide a constant current source under varying load.

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.

Demand for voltage-controlled current sources (VCCSs) and multipliers in a wide spectrum of electronics and communication devices always seems to exist. The multipliers employed in circuits like ...

It also had low saturation voltages capable of handling large collector-emitter currents with almost zero gate current drive. In 1997, the first experimental voltage source converter (VSC) HVDC system ...