Free circuit schematics - wiparat.com

This 555 timer based PWM controller features almost 0..100% pulse width regulation using R1, while keeping the oscillator frequency relatively stable. The frequency is dependent on values of R1 and C1, values shown will give a frequency range from about 170 to 200 Hz. Any 555 chip will do, CMOS is fine as well. Diodes [...]

The following diagram is for the main circuit of the motor driver. A testing version is shown later on this page. The testing circuit is laid out differently and shows the SN7474 in logic block form and LED’s are used to indicate the motor coils being switched. [....]
Read more : Basic Stepper Motor Driver [...]