Favorite 9v powered LFOs? For Escobedo's PWM

[spectraljulian]

I've tried a couple more LFOs out, all based around a dual op-amp, and nothing's giving me the kind of sine I want.  I'm thinking maybe instead of having a control voltage LFO, it might be better to have an LED/LDR resistance driven LFO. 

Suggestions?

The tremulus lune looks good, but it's got about three too many controls.  Of course I could hard wire them though.

The tremulus bear looks interesting as well. 

[Top Top]

What is the actual issue with the sound of the LFOs you have tried? I am wondering if it is something to do with the PWM's response to the voltage more than the actual shape of the LFO.

[soggybag]

wire the top Pulse Width pot and the bottom one the same, unless you want each pot to have the opposite sweep.  

You could use a dual pot for them, but then you couldn't set them in two unique positions.  Well, technically you could wire the terminals so they'd be opposite, but that wouldn't give you the full spectrum.  

The phase could also be replaced by a resistor at whatever value you like best.

Of course, breadboard it before you commit, and breadboard the original design.  Sometimes simplicity is best.  

I've wanted to give this a try for a while. It's a pretty simple project. Your idea looks intriguing.

Why not use a dual op-amp and make an active mixer? Seems it would take up the same space, and wouldn't really add more parts.

Not sure but, I bet you could trade the 386 and the TL081 for a dual op-amp and have what you have here with one less chip.

[spectraljulian]

What is the actual issue with the sound of the LFOs you have tried? I am wondering if it is something to do with the PWM's response to the voltage more than the actual shape of the LFO.

That's exactly what I'm thinking, which is why I want to try a resistance based.  I need to order some 500k LDRs from futurlec now. 

[spectraljulian]

wire the top Pulse Width pot and the bottom one the same, unless you want each pot to have the opposite sweep.  

You could use a dual pot for them, but then you couldn't set them in two unique positions.  Well, technically you could wire the terminals so they'd be opposite, but that wouldn't give you the full spectrum.  

The phase could also be replaced by a resistor at whatever value you like best.

Of course, breadboard it before you commit, and breadboard the original design.  Sometimes simplicity is best.  

I've wanted to give this a try for a while. It's a pretty simple project. Your idea looks intriguing.

Why not use a dual op-amp and make an active mixer? Seems it would take up the same space, and wouldn't really add more parts.

Not sure but, I bet you could trade the 386 and the TL081 for a dual op-amp and have what you have here with one less chip.

I don't really see the point in actively mixing the outputs because I'm not really worried about the cons of passively mixing the two.

But adding a dual op-amp to take over the functions of the 386 and TL081 make sense.  I guess I need to know more about these common op-amps though, so I would know what dual op-amp would best replace the two. 

[soggybag]

The 386 in this configuration has a gain of about 200. You could easily get this much gain from two op-amps.