erm... pwm ??

[1878]

Hello Everyone...

Bit of a strange question here, but I've got to ask it. I've recently finished Tim E's PWM without the LFO, but I've got a bit of a problem... I don't know what it's supposed to sound like !?!? Basically, It's ended up as a really nice fuzz with a 'sweepy' tone control. Is this correct ??

Correct or not, I really like it so I'm not gonna change it, but I've got enough parts to build another if I've bollo***ed this one up 

Thanks.

[bluesdevil]

You've got it right. I have some clips posted on the Basic Audio site sound page, but there's a mistake in the description.... there wasn't any distortion added outside of what the pedal produces, a very thick fuzz. Also I recommend the LFO add on 'cause it really brings it to life!!

[1878]

Thanks for the reply...

I'd make the LFO switchable if I added it 'cos I can see a problem, which is, at the most extreme setting of the frequency pot, the sound disappears completely !! I've used the correct parts and values throughout, so again, I don't know if this is a characteristic of my build or the effect itself. If the LFO sweeps through the full frequency range, it'll cut out at the extreme 'high-end' making almost a tremelo effect.

Cheers.

[SonicVI]

That's what it's supposed to do, almost like a thru-zero flange sound.  That's the point at which the width of the pulse (rectangle wave) is getting narrower and narrower so that it effectively disappears.

[Dragonfly]

Not verified, but looks correct.....let me know if you spot any errors

[bluesdevil]

 Has anyone seen a layout for the added LFO version? I remember having a hard time putting it together, might be good for newbies like I was back then.

[johnadon]

An expression pedal is totally awesome with this circuit as well. It sounds like an alien wah pedal. You do have to put a limiting resistor in series with the resistance in the expression pedal because of exactly what you mentioned: at the extremes of the pulse width modulation the sounds disappears. I actually added a pot rather than a fixed resistor to vary the the limiting so I could change the range of the pwm. Tim Escobedo's circuits are crazy fun!

[1878]

Has anyone seen a layout for the added LFO version? I remember having a hard time putting it together, might be good for newbies like I was back then.

That would be very useful indeed if anyone's got it !!