Re:load is low cost adjustable constant-current load with self-powered (passive). The circuit is simple and easy to build. It uses BTS117 FET as main pass element. The FET has built in ESD, overcurrent, overvoltage, and over temperature protection, making them ideally suited for a dummy load. MCP6002 op-amp is used in this project because it can handle input voltages near the ground rail, provide output voltages near the positive rail, and have low offset voltage for accurate operation.
The dummy load operates with 3.3 to 30V at 0-3A and dissipates up to 12 watts continuously at room temperature. Nick Johnson said that this dummy load is virtually indestructable as long as your input doesn’t exceed 30V. If you are interested to build this cheap dummy load, you can check the schematic here.