A variable frequency sine/triangle wave generator

[mister_e]

the beauty with mAX038 is that you don't have to care about the filtering. If you use a double integrator, you'll have big loss if you don't play with the R or C values.

Sure they are a bit expensive but they work good. Probably the best solution if some wants to do a bench Freq Generator.

EDIT: mmm seems i need an update... oups..

This product was manufactured for Maxim by an outside wafer foundry using a process that is no longer available. It is not recommended for new designs. For further information, contact us. The data sheet remains available for existing users.

forget me... i'll maybe in the deep shXX one day. i have thousands of those on the market now.. ARRGH! No i'm not going to sold the 500 i still have in stock...

 

[audioguru]

I have a Wien Bridge sine-wave generator whose amplitude bounces and bounces and bounces and ... whenever its frequency is changed.

I also have a phase-shift sine-wave generator that is tuned with a 3-stage pot.

I also have a very low distortion sine-wave generator that makes a fundamental with 10 digital steps and is smoothed with a pair of switched-capacitor lowpass filter ICs.

I used to have a sine-wave generator that made a crappy sine-wave out of a triangle wave using an ICL8038 IC.

 

[user1453]

Ok guys thanks for all the help I'll use a dual op amp setup ag audioguru suggersted, one op amp to generate a square wave, the other as an integrator

it will be like this

 

[peanutboy]

trying to build this

Hello,

very much a newbie at building electronic circuits.

I have some op-amps (386 and 741)

trying to make a triangle wave.

this schematic looks nice, though I am not sure what pins to use or which parts are represent.

any help available?

I do realize this thread is now a couple years old.

thanks in advance

 

[audioguru]

An LM386 is a small power amplifier, not an opamp.
A lousy old (40 years old) 741 opamp has trouble above only 9kHzand is noisy. Better opamps go well up to 100kHz and are low noise.

 

[peanutboy]

op amps

okay, but these are what I have to work with, is there any sort of tri or sine wave I could make wth these chips?

 

[audioguru]

You can make a low frequency triangle-wave with two 741 opamps.
The datasheet of the LM386 shows how to make a Wien Bridge sine-wave oscillator with a light bulb to stabilize the amplitude.

 

[peanutboy]

low freq tri wave

is there a schematic available for this low frequency triangle wave oscillator?


thanks much.

 

[audioguru]

is there a schematic available for this low frequency triangle wave oscillator?

5 or 6 posts above this post.

 

[peanutboy]

right, but as my original post in this thread stated, I am not sure which pins this schematic is referring to on the chip.

I am assuming the - represents pin 2 and the + pin 3? what pin is represented by the output? what type of caps and resistors hould I be using?

 

[audioguru]

Look in Google for Triange Wave Generator Circuit and you will find links that explain all about it.
Look at the datasheet for the uA741 or LM741 and the pins will be explained.

 

[peanutboy]

okay, I hooked it up and nothing is happening, I am getting some sort of sound, a harsh fuzz. doesn't sound like a triangle wave. I still found no advice on what capacitance and resistance to use. what does Rt as opposed to R1 and R2 represent?

 

[audioguru]

An opamp cannot drive a speaker. The oscillator can drive an LM386 power amp that can drive a speaker.
The oscillator cirrcuit uses a dual polarity supply.

The first link in Google has the details of the circuit: https://hobby_elec.piclist.com/e_ckt16.htm It uses a dual opamp so its pin numbers are different than the single 741 opamps.

 

[peanutboy]

building....

I was getting no sound even though I was using powered speakers.
I built according to the non labeled schematic in this thread using two 741s with the + and - pins corresponding to the 741 data sheet.

So... I do however need to be powering a non-powered speaker in the long run. It looks like my best bet is to build an oscillator with an on board amplifier. I have a nice schematic for an lm386 amplifier. perhaps I could just build it right in.

I did not realize how over my head this stuff was going to be when thinking up this project.

I prototyped all of this in software and am attempting to achieve the same results away from a computer in a relatively small package.

argh,

- peanutboy