Frequency Adjustable, Out of Phase sine wave Generator

[clone477]

Wanted to say hello to everyone,
This is a really informative forum, I have ben looking through it the last couple days, and decided to join.

I'm interested in pursuing a project dealing with rotating magnetic fields, same type used in AC motors. But I want to build a circuit that I can adjust the frequency of the circuit, from 60hz- to at least 12khz. I also want it to be able to deliever around 10amps, 12v. The thing is I need to build this circuit to create two sine waves, 90 degree out of phase, for my rotating magnetic field.

Ive been searching like mad for a DIY circuit I could build, but no luck, Im hoping someone could shed some light on this for me. My electronic skills are almost at the intermediate level, followed a circuit diagram to build a pulsed square wave generator with PW and frequenct adjust. Thanks in advanced for any help. Fern

 

[ccurtis]

I came across this simple µC solution from Electronics Design magazine. The two outputs from the PIC can be amplified with a 120 watt (min) stereo amplifier to meet your power output requirements.

A quadrature generator can be useful in a number of applications, such as motion control and signal processing. The idea presented here describes a very simple and inexpensive implementation of a quadrature generator using a single 8-pin IC, the Microchip PIC12C508 (See the figure).​

**broken link removed**

A few NCO or DDS chips (see Harris or Analog Device, for example) can generate the variable frequency quadrature signals, also. The chips are available with internal D/A converters to generate decent quality sinusoids directly.

 

[clone477]

Thanks for the reply, that site describes what I need pretty well. Would anyone be willing to put a schematic together with a frequency adjust option?? I have no problem paypaling someone some cash for there help.

 

[ccurtis]

https://focus.ti.com/lit/ds/symlink/4423.pdf

This is a single device solution with schematic shown. The frequency is resistor/capacitor programmable. The internal schematic of the device gives a clue as to how to do it with seperate op amps if you want to go that route.

Of course, you still need a powerful amplifier to deliver your power requirements.

Also, I see a number of simple quadrature audio range oscillators using a google search. Search on "quadrature oscillators"

 

[clone477]

Ccurtis,
You what is great about that, is that I actually understand it, its pretty simple. What would you reccomend to amplify the signal to feed my coils??

 

[ccurtis]

I had in mind an off-the-shelf 120 watt stereo audio amplifier. Look at the specifications to make sure it can meet your 60 Hz response. You don't want to build one of those do you? If so, you are talking about big power components and power supplies. Probably much cheaper to buy than make, and a whole lot easier.

 

[clone477]

I wanted to thank everyone thus far for there help. After all the appreciated suggestions, I decided on using signal generating software. It will produce sine, square and trianle and has adjustable frequency and phase between left and right channel. Exactly what I need. I need to feed this out of my soundcard to an amplifier. I have tried a audio amplifier, but it did not work properly. What can you guys suggest to use for ths, either built or purchased. I also realized that I dont need those high power ratings as I once though, so Im pretty open with that aspect. But I also realized I need atleaset 100KHZ, which my software can produce, but I dont think my aplifier can reproduce. So I need help amplifying this signal to continue. I hopping someone could suggest an amplifier that would be able to output tose high frequencies. Thank for any help guys. Fern

 

[clone477]

There was one other thing I forgot to ask. If I wanted to play with my benchtop signal generator in the meantime, how do I determine the capacitor needed to change the phase by 90 degrees. I'm thinking of taking the parellel outputs from my signal generator and running one set of terminals through a capacitor to alter the phase. I searched like crazy for this. Any ideas??