Stainless Steel Reaction Time Tester, Usage Application: Hospital at Arduino based Reaction Time Tester freetronicsblog Make It: Advanced Reaction Time Tester Project (javascript reaction Figure 2 from Portable Reaction Time Measurement Device: Prototype Reaction Time Tester Engineering Kit with Circuit Diagram (No Soldering Required) Circuit design Reaction Time Tinkercad. The Reaction Tester is based around the 555 timer IC. The kit is designed to test and expand one's sense of timing. The students need to synchronize their reaction time to press the button in time to keep the LED lit or else it goes out. Note: Step by step instructions are not included use the included parts list to identify the components and assemble according to the included circuit diagram. Jumper wire not included (breadboard accepts 21 to 26 AWG wire).