In operation, the circuit is a straightforward DC summing amplifier of the type that op-amps were designed for and at which they excel.

He used this knowledge to design a device called Op Art which generates Spirograph shapes on your oscilloscope using just a handful of op amps.

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.