How Do I Generate Quarter Sine Waves?

In summary, Dave is trying to generate a quarter sine wave with a good function generator. He suggests a simple circuit with a phase shifter and diodes to select the quadrant. He also mentions using a μprocessor and D/A to generate the waveform.
  • #1
forex10
27
1
Hello,
I need to find out how to generate a standing sine wave, or a quarter sine wave. I had no trouble finding out how to create a full or half wave rectifier, but very little generating a quarter wave, & that info mostly dealt with sound waves. I am doing this for experimental purposes. Please not I have a good function generator. Thanks for any help!
 
Engineering news on Phys.org
  • #2
You didn't specify the frequency, so maybe a relay.
 
  • #3
Correction: Please note I have a good function generator.
 
  • #4
Almost always 100K.
 
  • #5
Which quadrant do you want?
Draw the waveform you require. Post it as an attachment.
 
  • #6
If you have a good function generator, you have an advantage, for generating sine wave. What I would do is generate a square wave of duty cycle 75 percent(there are circuits in 555 which enable you to do)...Then, I would connect both this sine wave(amplitude is so low) and the square wave to a bjt transistor network. This network ensures that only quarter of the wave is passed( any quarter section of the full wave)
For the bjt network(use some bias if needed), use the sine wave as small signal...connect the sine wave to the base(through capacitor). The emitter can be grounded. The large signal is the square wave and you must connect it to the base through a resistor. Take the output from collector or emitter depending on the circuit.
 
  • #7
forex10 said:
Hello,
I need to find out how to generate a standing sine wave, or a quarter sine wave. I had no trouble finding out how to create a full or half wave rectifier, but very little generating a quarter wave, & that info mostly dealt with sound waves. I am doing this for experimental purposes. Please not I have a good function generator. Thanks for any help!

anorlunda said:
You didn't specify the frequency, so maybe a relay.

the freq is probably irrelevant

a standing wave ISNT going to come from your generator ... standing waves are generated on a transmission line when
the transmitted signal hits an impedance mismatch. At that time a reflection of the signal will occur and be reflected back
towards the transmitter ( generator) and standing waves with be generated when the forward and reflected signals interact

a 1/2 wave generator is just removing the other 1/2 of the cycle as said with a diode

the only easy way I could see to produce what looks like a 1/4 sine wave would be to generate a non-linear ramp voltage

quarterwave.GIF
maybe you should tell us more about what you are trying to achievecheers
Dave
 
  • #8
A simple quarter of a sine wave is probably a single quadrant. That suggests both a removal of one polarity and a time dependent elimination of one half of the “pulse”. To split the pulse in two requires a time dependent function. One way to generate that is with a phase shift of 90°. A low or high pass filter will do that. Then the quadrant of the sine wave must be selected based on the polarity of the phase shifted signal.
Attached is a circuit modeled with LTspice that attempts to do that without integrated components.
Only R, C and diodes are used. The R1C1 is the phase shifter.
The diodes form the quadrant data selector. The gate control must be higher than the signal so as to give a steep switching edge.
Quadrant.png
 
  • Like
Likes Tom.G and jim hardy
  • #9
I like Balun's thought process - analog phase control.
I was about to suggest a thyristor lamp dimmer
http://www.littelfuse.com/~/media/e...rol_using_thyristors_application_note.pdf.pdf

same phase control principles could be applied at a signal level using precision analog switches like DG614
https://www.vishay.com/docs/70050/dg411.pdf

Nowadays one can brute force it - use a μprocessor and D/A to output any function as a stream of numbers from memory...

[ moderator note: media link removed ]
 

1. What is a quarter sine wave?

A quarter sine wave is a type of periodic wave that oscillates between two values in a quarter period or one-fourth of a full cycle. It is commonly used in electronics and signal processing applications.

2. How do I generate a quarter sine wave?

To generate a quarter sine wave, you can use a function generator or a software program that has a built-in quarter sine wave function. Alternatively, you can also use a simple circuit with a resistor, capacitor, and voltage source to produce a quarter sine wave.

3. What is the mathematical formula for a quarter sine wave?

The mathematical formula for a quarter sine wave is y(t) = A sin(2πft), where A is the amplitude, f is the frequency, and t is the time. The amplitude and frequency can be adjusted to generate different shapes and sizes of quarter sine waves.

4. What are the applications of quarter sine waves?

Quarter sine waves are commonly used in audio and video equipment, such as speakers and televisions, to produce smooth and continuous sound and image signals. They are also used in communication systems, data transmission, and image processing applications.

5. How accurate are quarter sine waves compared to full sine waves?

Quarter sine waves have the same shape and frequency as full sine waves, but they only cover a quarter of a full cycle. Therefore, they are not as accurate as full sine waves in terms of representing a complete waveform. However, they can still provide a good approximation and are often used in practical applications due to their simplicity and easy generation process.

Similar threads

Replies
16
Views
1K
Replies
38
Views
3K
Replies
15
Views
2K
Replies
78
Views
3K
Replies
14
Views
2K
  • Classical Physics
Replies
7
Views
1K
  • Electrical Engineering
Replies
21
Views
1K
  • Electrical Engineering
Replies
2
Views
2K
  • Electrical Engineering
2
Replies
39
Views
2K
  • Electrical Engineering
Replies
4
Views
2K
Back
Top