While building a robot or some gadget that moves you may need dc digital servo motors.Servo motors are in general motors with low moment of inertia that can produce high torque and generally used for position control systems (eg.Radar antenna alignment etc),but what is used in say robotics is a small dc geared motor accompanied by digital circuitry that takes supply with respect to a ground potential and driven by pulses of specified pulse-width.
 |
| Hitec servo |
 |
| servo driver using 555 timer |
For moving a servo you need to generate pulses of 0.8ms to 2.5 ms. The above circuit uses astable multivibrator configuration with IC 555. The variable pot resistor and the capacitors are so chosen that their combination produces the necessary duty-cycle with the necessary pulse width.
If I get time I may upload the simulated oscilloscope snapshots. Let me know if it worked for you.
PS: This is a must for all hobbyists who are entering tech fests like Kshitij in IIT or building robots just for fun. But this circuit is only for beginners who does not yet know how to use a micro-controller or dont want to build that costly a circuit. This entire circuit will cost about 50 Rs or 1$.
