Teaching in the STEM field based on the simulation is the necessary for students to understand the concepts and materials that have been given. This paper presents a simulation performed using IC Timer to generate a square signal using a virtual laboratory circuit wizard simulation software. In conducting the simulation, there are stages that will be given to students. There are 10 stages that will be explained in the lab experiments section. The method used consists of design for simulation. With this paper, it is expected that future teachers can provide simulated teaching to their students well. The results obtained in the simulation using this IC Timer are square signals that can be generated by the IC Timer circuit, and the results of frequency calculations, both through theoretical calculations and calculations with an oscilloscope do not show significant results. Teachers can provide teaching to students through simulation with a virtual laboratory first before carrying out practice directly, so students can use real devices properly and can reduce the risk of damage.