ErikMiller-is your audio test oscillator amplitude stable?

[ExpAnonColin]

I just finished building an XR2206-based function generator, but I tried a few mods as I went along.  It looks similiar to yours-so I was wondering if you have the same problems as I do.
1) How high are the peaks of your triangle/sine output?  I'm only getting about .2v.
2) Is yours amplitude stable at all?  Mine is only .2v at the highest frequency and goed down to tiny voltages as I lower the frequency.  (not too low to see it move around, though, so I am measuring the peaks)
3) Does the amplitude control work sort of funky on yours?  My peaks get all messed up when I use it, it's more of a trim to get a perfect signal than a working amplitude controller.

Thanks,
Colin

[toneman]

Colin,
this shouldn't happen with 2206, 8038, or 556 or the MAX038.
the amplitude should remain constant.
R U driving something directly from the 8038 outs?

i usually buffer all the outs with an opamp, that way i can
add gain, since the harmonics are different with each waveform.

what schemo R U using?

tone

[ErikMiller]

Colin,

I'm looking at it right now, and powered with a 9V battery, I'm getting about 3.5V p-p before the peaks start to deform.

It's amplitude and frequency solid, that is, if you adjust the amplitude, the freq. doesn't move, and you can sweep the frequency and the amplitude stays the same. It would be much less useful to me were this not the case, as I wanted it for frequency response measurements.

The amplitude knob works well, you can go from an output that the scope can't detect all the way to 3.5 p-p with a very smooth-looking sine wave.

I didn't enable any of the triangle wave functionality, so I cannot speak for that.

Mine's pretty closely based on the app notes; I'm assuming you have those? Do you have the paper they wrote on building your own generator? It goes into greater detail. It's a separate download from the app notes.

[ExpAnonColin]

Colin,

I'm looking at it right now, and powered with a 9V battery, I'm getting about 3.5V p-p before the peaks start to deform.

It's amplitude and frequency solid, that is, if you adjust the amplitude, the freq. doesn't move, and you can sweep the frequency and the amplitude stays the same. It would be much less useful to me were this not the case, as I wanted it for frequency response measurements.

The amplitude knob works well, you can go from an output that the scope can't detect all the way to 3.5 p-p with a very smooth-looking sine wave.

I didn't enable any of the triangle wave functionality, so I cannot speak for that.

Mine's pretty closely based on the app notes; I'm assuming you have those? Do you have the paper they wrote on building your own generator? It goes into greater detail. It's a separate download from the app notes.

Ah, sounds like something is going wrong for sure then, I'm getting very low off of a 9v and it's not amplitude stable at all.  Where'd you get ahold of the building-your-own notes?

-Colin

[toneman]

PM me 4 the pdf.
U want just 2206?
tone

[ExpAnonColin]

PM me 4 the pdf.
U want just 2206?
tone

Sure, could you email it to me @ colin@experimentalistsanonymous.com ?

-Colin

[ExpAnonColin]

Thanks, Erik, for the sheet... I was trying to do it so that I could get a sine, triangle, square, and sawtooth, but I'm thinking no dice.  It seemed to be based on the datasheet that you get a saw by connecting pins 9 and 11, but it sure wasn't working for me.  Not sure why.

-Colin

[ErikMiller]

I was trying to do it so that I could get a sine, triangle, square, and sawtooth, but I'm thinking no dice.  It seemed to be based on the datasheet that you get a saw by connecting pins 9 and 11, but it sure wasn't working for me.  Not sure why.
-Colin

Ah, the circuit on page 10 of the app notes. What did you use for R1 on pin 7? The wording is confusing enough that I'd also try putting the same thing on pin 8 if you're trying to get the saw. Or vice-versa, depending on how you have it now. :-)

I'd try the sine/triangle and square/saw parts separately for debugging purposes.