DIY Electronic Kit Metal Sensing Detector MINI Handheld DIY Soldering Make It: Advanced Reaction Time Tester Project (javascript reaction Reaction Time Game Arduino Project Hub Make It: Advanced Reaction Time Tester Project (javascript reaction. 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).