LFO & Audio Oscillator: Same circuit diff. caps?

[D Wagner]

Hey Pedal Fiends,

I have been breadboarding and studying a lot of LFO's and audio oscillators.

While either can be built literally hundreds of ways, it seems to me that the basic difference is that the caps used put the circuit in different audio ranges.  

My primary reason for trying so may circuits is that I'd like an audio oscilator which can have it's frequency varied with a pot, AND be modulated with the LFO (tremolo).  The LFO has to do double duty, as it is also the LFO for a simple guitar synth.

Right now, I am using a dual opamp setup for the LFO (from the Jung book, I think) and a twin tee for the audio oscillator (again, textbook stuff.......simple but effective.  I have ordered a few 74LS04  Hex Inverters to experiment with.)

Any thoughts on compatibility between circuits, noise, ticking, etc?  (I abandoned the 555 oscillator due to the annoying tick that wouldn't go away.)  

Does anyone know of a circuit that can do double duty as both an LFO and audio oscillator, with a few cap changes?  (Two circuits, same PCB pattern)The breadboard is waiting. :wink:

Thanks in advance.

Derek

[Paul Perry (Frostwave)]

Thge only trouble I have seen in trying to 'downconvert' audio oscs to very low freq oscillators, is that sometimes you get an asymmetric waveform (the triangle is all over one side). This is I think a sign that the (very small) current beign integrated to make the triangle is being swamped by leakage, so you need low leakage op amps.
And also once you start uswing electrolytics to get big cap values, there is leakage right there..

[brett]

I abandoned the 555 oscillator due to the annoying tick

The CMOS 555 has lots less noise, and dummies like me like its simplicity.  I've also used the 40106(?) trigger at high frequencies and found it really useful.

cheers

[RedHouse]

I like to build on the XR2206 which works very well and doesn't get hot like the ICL8038, which both have multiple wave shapes available simultaniously.

(XR2206 freq range: .01Hz to 1MHz)

I'm going to convert my univibe clone to use the XR2206 soon.