Albert Einstein He developed the general theory of relativity, one of the two pillars of modern physics (alongside quantum mechanics).

The first integrated circuit invented by the engeneer Jack S. Kilby1 (1923-2005) contained only a few transistors. Texas Instruments.

Full part list (Arduino based RPM meter)

IR LED and senosr: LINK
Arduino NANO: LINK
LM324 amplifier: LINK
Push button: LINK
Slide button: LINK
OLED screen: LINK
30AWG wire: LINK
Cheap lser diode: LINK
9V battery connector: LINK
9V battery: LINK
drilled PCB: LINK

Arduino rpm meter full parts