Design Challenge #2

[fig]

Spice component models are mostly text files with component parameters and specs that can be edited. Mouser and others include Spice model documents along with the normal data sheet.
If you place the file in your library include path, it should find it as a listed component.

Here is a link to the SPICE model for the CD4049UB from Mouser. Hope it helps!

http://www.ti.com/litv/zip/schm019

 

[rankot]

Spice component models are mostly text files with component parameters and specs that can be edited. Mouser and others include Spice model documents along with the normal data sheet.
If you place the file in your library include path, it should find it as a listed component.

Here is a link to the SPICE model for the CD4049UB from Mouser. Hope it helps!

http://www.ti.com/litv/zip/schm019

This lib is for logic behavior of CD4049UB, and that is now what we need for audio simulation.

 

[Chuck D. Bones]

"now"? I think you mean "not"

I agree, those models won't work for analog simulation.

There are analog models for the N and P devices in the CD4007 and CD4049. I use those in my sims. Pretty close match to breadboard test data.

 

[slammer88]

I have some CD4007UBE's at hand and I had no idea what to do with them, then after some research, I found that they can be used for an overdrive, even distortion circuit.

I've traced the following vero layout, made some changes, and made my first breadboard circuit.

https://www.parasitstudio.se/stripboard-layouts/nut-cruncher

It worked! It's a true beast, when entered a clean channel of the amp, it sounds much like a child of HM-2 & Muff, and when on the dirty channel, it becomes a true monster. I've also added a modified BMP tone circuit with a heavy mid-boost, and it also works great. Also, when the 4.7uf output cap's positive side is connected to the 13th lug instead of 12, the overall output gain drops and the circuit acts like an overdrive pedal, sort of a booster maybe. I plan to add a switch for that. I also want to play around with other parts more to see their capabilities and how they affect the sound. It's also quite silent... But;

There's this slight yet weird problem.

The gain pot works as it should be, but during its range movement, it hums a bit; it is more like a grounding issue, but everything is grounded, and when the gain is set to full, it's working quite normally, no hum or buzz or nothing at all, but when I move the pot, it's humming a bit during its travel. I tried several different tapered pots with different values, but no luck. Connecting a single resistor works indeed, but then I don't have any adjustable gain setting.

What would be the cause do you think? I tried directly grounding the 1st lug of the Drive pot, but still no go.

One rule I read yesterday -which I also violated here- is that no pins should be left floating on any CMOS chips, but in my case, pin 3 of the chip (Gate 2) became unused and I could not find it anywhere to connect. Any ideas are most welcome. This is my first experience for;

- Breadboarding a circuit,
- Modifying a circuit,
- Working with CD- chips,
- Drawing a schematic from a Veroboard,

So please don't go harsh on me

Attached is the schematic I've prepared according to the layout then modified.

 

[Chuck D. Bones]

Why would you leave pin 3 floating? Take a good look at your schematic, because as-drawn it has problems.

You may have noticed that I draw the CD4007 as 6 MOSFETs so it is easy to see what's going on. An IC drawn as a rectangle with 14 pins makes it much harder to visualize the circuit.

This not a troubleshooting thread for your circuit, so I'd appreciate it if you started a new thread.

Thanks,

- Chuck