The previous oscillators that use gatesshown in this section, and the 4093 in the basic version, are symmetrical because fifty percent of the time the output is at the “'1" logic level, and the other fifty percent at the “0" logic level. We say that they are square wave generators or the duty cycle is 50 percent. If different duty cycles are needed, you can use other configurations. The duty cycle for this oscillator depends on the resistors R1 and R2. The mark depends on R1. The space depends on R2. The diode is any generaI-purpose unit, such as the 1N914 or 1IN41I48. With the values as shown here, operation frequency wiII be in the audio range.
Programming the Duty Cycle
