This is a 555 timer in Astable mode which can generate a frequency with a low duty cycle in order to control a single Servo motor (90+-). By changing the resistance value of POT1 you can change the duty cycle of the timer roughly within the same frequency (19Hz) which in turn will change the position of the servo motor arm.
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Below you will find the circuit schematics and list of parts for this setup, and also a video showing step by step how to build the circuit on breadboard.
Components list:
IC1 – 555 Timer
R1 – 56K
R2 – 3.3M
POT1 –100KΩ
D1 – 1N4148
C1 – 22nF
Step by step video guide on how to build the circuit according to the schematic above