I built CD4047 IC based inverter circuit earlier. Here I will show how you can use online CD4047 frequency or resistor calculator making the design process easier.
The following is the circuit diagram of the CD4047 inverter circuit that I designed earlier.
In the circuit the value of resistor RV1 and capacitor C1 can be calculated using the online CD4047 calculator. The calculator is showing 45.45 kΩ because it is solving the formula for 50 Hz final inverter output.
The Math Behind the 45.45 kΩ
The calculator uses the official datasheet formula for the CD4047 in astable mode:
When you enter 50 Hz as your target value, the calculator performs the following steps:
Targeting the Output: Since the CD4047 divides the internal oscillator frequency by two to create the complementary $Q$ and $\bar{Q}$ signals for your MOSFETs, a "Target Value" of 50 Hz in this specific calculator implies the final inverter output frequency.
Calculating for 100 Hz: To get that 50 Hz output, the internal oscillator must run at 100 Hz.
Solving for R: Using $C = 0.1\mu\text{F}$ ($1 \times 10^{-7}\text{F}$), the math is:
$$R = \frac{1}{4.4 \cdot 50\text{Hz} \cdot 0.1\mu\text{F}} = \frac{1}{0.000022} = \mathbf{45,454.5\Omega}$$Result: This rounds exactly to the 45.45 kΩ
Now see the image below, the RV1 is a 100 kΩ potentiometer which is set to as 45.45 kΩ shown below.
