analog function generator theory schematic

[walters]

Where can i find schematics for analog function generators and analog Arbitrary function generator schematics?

Whats the block diagram of a analog fucntion generator and a analog arbitrary function generator ?

Its like VCO>>>wave-generating functional blocks?

I'm trying to learn the Stages/blocks inside a function generator and a Arbitrary function generator what are they from each stage until the output?

 

[Thunderchild]

try looking up the 8038 IC it is quite useful in making a simple function generator

 

[panic mode]

chips like 8038 are not arbitrary function generators. they simply generate predefined functions using VFO and signal shaping/conditioning.

arbitrary function generators can produce any shape of signal user wants (programs it). simple approach is to have oscillator of variable frequency (clock) driving counter. counter outputs are used to address memory location (incrementing/decrementing). value from addresses memory location is converted to analog signal (DAC). memory can be (E)EPROM for example but this is not convenient way of changing program (wave shape). it is common to use MCU for example. this way MCU can communicate with computer to receive new programs.

 

[walters]

signal shaping/conditioning

Where do i find these circuits signal shaping or wave shaping circuits or stages

I can't find wave or signal shaping circuit schematics that are analog like in function generators

 

[mstechca]

signal shaping/conditioning

Where do i find these circuits signal shaping or wave shaping circuits or stages

I'm kinda confused.

but if you are looking for a circuit that produces a wave, you are looking for an oscillator, or anastable multivibrator.

Do a search on oscillator and you will get your answer.

 

[walters]

No not the oscillator or VCO part the waveshaping stage AFTER the VCO or oscillator because all a oscillator or VCO does is produce square,sine,triangle and then Waveshaping or signal shaping stages,circuits,blocks change it

 

[panic mode]

they only make basic changes (saw tooth, rectangle, etc.).
it is impossible to make analog device that will allow any desired signal shape on the output. this is why arbitrary function generators are using digital technology and lookup tables. you can make simple analog generator using oscilator, counter(s) such as 4017 and connect potentiometer to each output. connect all wipers through diode to comon point and amplify signal with an opamp for example. with each potetiometer you can adjust amplitude of the output signal for one single step. depending on number of steps you could have more or less complex output.

 

[walters]

So you saying to hook up like 4 function generators and get a Summing amp or mixer to sum or mix different sine/triangle/square waveforms to create complex waveforms?

 

[panic mode]

no,

do you understand concept of "lookup table"?

 

[2PAC Mafia]

Hello,

I made one using the I.C. XR2206 and I have sinoidal, triangle and rectangle. I have the schemes on a book...

 

[audioguru]

The schematics for the ICL8038, MAX038 and XR2206 function generator IC circuits are in their datsheets. Frequently an entire project is shown with parts lists having manufacturer's part numbers and even a pcb layout. They also describe how they work with good detail.

 

[mstechca]

I saw once on Harry's homebrew homepages that he uses an EPROM to create a customized wave. This may be similar to what you require.

Do a google search for "Harrys homebrew" and go to the projects, and then EEPROM circuits section.

 

[panic mode]

yep, that's a very simple one:
**broken link removed**

 

[audioguru]

Take a square wave, a perfect one from a digital divider, and feed it through an 8th-order switched-capacitor Butterworth lowpass filter IC and the resulting sinewave is nearly perfect with only about 0.05% distortion.

Take a clock frequency that is 10 times higher than the output and clock a CD4018 Johnson "walking-ring" Counter with 4 output resistors to make a stepped sinewave that is actually oversampled. Feed it through an 8th-order switched-capacitor Butterworth lowpass filter IC and the resulting sinewave is perfect with unmeasurable distortion, like I have in my audio generator. The counter and resistors perform like the ones in Harry's Eprom circuit. :lol: