Re-Post: This is a great LFO design.

[ExpAnonColin]

Very nice integration of your average dual OA LFO and the diode->sawtooth configuration that's less commonly used.  I'm going to build me one of these!  Still not perfectly amplitude stable, but at low frequencies you should be fine.  And, correct me if I'm wrong, but you could easily switch the +/-9v supply for a +/-4.5v, you'd just get lower P-P.

Thanks to charlie for posting the site with it and Ray Wilson for drawing it.

-Colin

[Jason Stout]

Is that Ray's drawing and circuit?

[travissk]

Yep, Colin mentioned it; it's hidden underneath the massive image  

Looks very cool, I might build one sometime in the future too

[mikeb]

Looks like it ....

Mike

[Paul Perry (Frostwave)]

Before anyone asks, it *MIGHT* work without a LF444..... but, it *WILL* work with a LF444.

[christian]

Why is ramp called ramp and sawtooth called sawtooth??
Have you tried with just variable resistors in series with the diodes? I don´t know if it works with 3-tapped pots as level pots(some voltage flaw?), but you´ll get separate rise and fall settings. That´s neat!

[ExpAnonColin]

Paul-I vote yes!  I'll probably try this tonight.

-Colin

[puretube]

these kinda circuits work with LM324,
and single supply.....   :wink:

[Mark Hammer]

Why is ramp called ramp and sawtooth called sawtooth??

In truth, they essentially the same wave form, just bumped over a half cycle, the same way a 90% duty cycle and 10% duty cycle pulse wave are also the same sort of audible waveform.  Where is starts to make a difference, though is when the waveform is synchronized with something else that has the same "starting point" (e.g., two synced VCO's) or if the waveform is produced in a one-shot manner.  For instance, look in issue 2 of DEVICE at my site and you'll see some designs for envelope generators where the envelope voltage produced either descends OR ascends (sawtooth vs ramp).  In that context, the sawtooth vs ramp distinction makes sense since the one would produce a sharp attack with drawn out decay and the other would produce a slow attack with fast decay.

[puretube]

I prefer the terms "ramp up" and "ramp down", or
"saw up" & "saw dwn"...

[ExpAnonColin]

I prefer the terms "ramp up" and "ramp down", or
"saw up" & "saw dwn"...

Tomato/tomato?

-Colin

[puretube]

ahh, yes - I understand...

[christian]

that was just a *wink-wink* question. saw the ?

Speaking of ramps, I don´t remember what forum it was, but there was quite heavy debate(I think it even went to a personal level!) about the fact that can you hear a difference between ramp up/down sawforms when they are running in audio range(50Hz-XKhz). That was amusing to read.

I prefer ramp-up and ramp-down too. It´s a ramp if goes down and ramp if it goes up and it´s sawtooth whatever way it is, so adding the word up/down clears things a little.

[puretube]

that makes the standing

two to tomato

:lol: