I show the behavior of a transistor multivibrator by changing the capacitor values. The first configuration is symmetrical with two 100 uF electrolytic capacitors. Next, I replace one of these with a 22 uF capacitor and the pulse becomes obviously asymmetric. Last, I remove a 100 uF capacitor and replace it with 47 uF. The pulse remains asymmetric but different than before. This is a simple, low-cost way to achieve different oscillating patterns. PS: Wow, my breadboard is dirty from 20 years of use/abuse.