Creating a 90 Degree Phase Shift with a Sine Wave

[edmondng]

I have a sine wave. i want to make it 90 degrees out of phase. if i remember correctly i could use a capacitor to create a phase lag of 90 degrees (like on of those motors where they put a capacitor to create the offset so it starts to turn)

Do you put the capacitor in series? What value? putting the cap would just make it ac coupled not sure if would do the lag
If not, how can i create a 90 degrees phase shift

edit: i guess a differentiator would work. any other simpler way through circuit? my op amp is configured non-inverting input

Thanks

 

[berkeman]

To get a -90 degree phase shift in voltage, you can run your voltage source signal through an inductor and then a resistor to ground. Well above the LR breakpoint frequency, the current through the inductor will lag the voltage across it by 90 degrees, and so the output voltage across the resistor will also lag the input voltage by 90 degrees.

 

[ravenprp]

for sharing your question and thoughts on creating a 90 degree phase shift with a sine wave. You are correct in thinking that a capacitor can be used to create a phase shift in a sine wave. However, the placement and value of the capacitor will depend on the specific circuit and components being used.

In general, to create a 90 degree phase shift, the capacitor should be placed in series with the input signal. The value of the capacitor will depend on the frequency of the input signal. The formula for calculating the required capacitance is C = 1/(2πfR), where C is the capacitance in farads, f is the frequency in hertz, and R is the resistance in ohms. For example, if your input signal has a frequency of 1kHz and you want a 90 degree phase shift, you would need a capacitor with a value of approximately 159 nF (C = 1/(2π * 1000 * 1) = 159 nF).

Using a differentiator circuit, as you mentioned, is also a viable option. This type of circuit uses a resistor and a capacitor to create a phase shift in the input signal. Again, the values of the resistor and capacitor will depend on the frequency of the input signal.

Overall, the best way to create a 90 degree phase shift will depend on the specific circuit and components being used. It may be helpful to consult a circuit designer or do some research to find the most effective method for your particular setup. I hope this helps and good luck with your project!