That is like saying you need a car with wheels.
What frequency pulse ?
What duration ?
What ratio of high to low ?
If 555 schematics are too much, I really reccommend getting a Velman. Easy to solder, some are prebuilt.......
K8004: VELLEMAN INC.: Education & Hobby they list it as a Expert kit........
If you can use a knob this
QKits Electronic Kits: MX033, PWM DC Motor Speed Control Module will work. It is also possible to replace the variable resistor with your 0-5V signal.