4049 wah?

[thomas2]

http://www.geocities.com/munkydiy/4049wah.jpg
this looks interesting to me.. i have a few 4049's lying around anyway..
i'm just wondering why there's no component values in the schem?
does someone know what they should be?
:shock:

[thomas2]

oh.. if the link doesn't work, just go to the munkydiy site and look for it

[gez]

It's a sketch that Ansil got together.  Doesn't look as though it would work though.  

You can use CMOS for a wah circuit though.  The whole crybaby circuit can be lifted and re-done using a 4007.  (inverter as the amp with AC feedback de-coupled, one MOSFET for the follower and another for a buffer).

I didn't have a proper inductor when I did this and had to use an output transformer, but it sounded exactly the same as the tranny circuit with the same transformer in it, so it might sound good with the real thing in there (output transformer resulted in a pretty poor wah).  

The 4007 meant that the parts count was slightly lower (just as noisy mind).

[R.G.]

From a look at the circuit, I don't think it would work as shown. There needs to be at least a DC blocking capacitor in the path leading from the inductor through a resistor back to the input of the first inverter.

It can probably be made to work. Almost any gain stage works instead of the first transistor in the classical wah circuit, and almost any follower works instead of the second transistor. I show a design of an opamp based inductor wah in "The Technology of Wah Pedals" at GEO, using a common opamp to replace those transistors.

[Tim Escobedo]

I'm wondering if it'll work without another inverter to invert the "feedback" signal driving LCR network. Also, CMOS inverter outputs tend to be fairly high impedance, possibly reducing the efficiency of the LCR network. Perhaps a bit of gain could make up for such losses?

[thomas2]

i have no idea what you just said  :lol:
read from below what this McGyver doesn't know

[Nasse]

Also, CMOS inverter outputs tend to be fairly high impedance, possibly reducing the efficiency of the LCR network. Perhaps a bit of gain could make up for such losses?

I posted an old "hi-fi" circuit few days ago, that has a bipolar transistor connected as emitter follower directly at output of inverter stage. Quess that cures the high impedance problem, but dunno if that ruins inverter tubeyish sound :roll:

[puretube]

free information sucks...