BAJA Korg CX3 Rotary Effect  [documentation]

Original effects with schematics, layouts and instructions, freely contributed by members or found in publications. Cannot be used for commercial purposes without the consent of the owners of the copyright.
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Reachahighernoon
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Post by Reachahighernoon »

So I decided to try and draw my own version of the schematic that uses 3207 chips

Any glaring issues that you guys are spotting?
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Schematic_BAJA CX3_2021-08-04.png

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poulto
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Post by poulto »

Does anything like this exist on the market? I'm looking for this exact effect - it looks like it's pretty much a BBD chorus pedal that spilts the highs and lows and gives a similar effect to a Leslie speaker... And I want it this way because I want to plug it into a guitar or bass amplifier, as opposed to using it as a speaker sim itself.
Is anyone offering these or anything like them commercially?

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Reachahighernoon
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Post by Reachahighernoon »

poulto wrote: 03 Apr 2022, 07:47 Does anything like this exist on the market? I'm looking for this exact effect - it looks like it's pretty much a BBD chorus pedal that spilts the highs and lows and gives a similar effect to a Leslie speaker... And I want it this way because I want to plug it into a guitar or bass amplifier, as opposed to using it as a speaker sim itself.
Is anyone offering these or anything like them commercially?
I searched high and lo for an existing PCB for this type of effect and I have found nothing so far, sorry

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Maximus
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Post by Maximus »

Hi, long time that I´ve been here.

I breadboarded this, very nice, but I'm getting a lot of noise. Sounds like intermodulation between the two LFO's, hi frequency so I guess from the 4046's.
Have any of the people that made it had the same problem?
While thinking about it, I've noticed something odd in the schematic: R30, bias resistor for Q5/6 is taking power from the power node number 3, that feeds the lo frequency MN chip and its associated 4046. Seems odd, and a possible point of noise injection.
Will try feeding it from another power node to see what happens. Report soon.

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bmxguitarsbmx
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Post by bmxguitarsbmx »

Hey Maximus. Noise is probably going from the digital section to the analog section through power supply and ground. Its tough when breadboarding, but try to isolate the digital from the analog section, then join the two grounds at one point only.

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Maximus
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Post by Maximus »

OK, tried isolating the grounds of the 4046's with resistors up to 1K, upping the lopass filters of the power, and a few other things. No sucess yet. I heard some demos that someone made and posted in this thread, and it seems to be working well for the poster. And I guess for Bajaman too.
So, what's wrong with mine?
I used CD4046, while the layout mentions HEF4046's. Might that be the problem? Hmm.

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Maximus
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Post by Maximus »

I´m using MN3007, not MN3004, but it should be no problem...

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Post by bmxguitarsbmx »

Maximus wrote: 20 Feb 2024, 23:09 OK, tried isolating the grounds of the 4046's with resistors up to 1K, upping the lopass filters of the power, and a few other things. No sucess yet. I heard some demos that someone made and posted in this thread, and it seems to be working well for the poster. And I guess for Bajaman too.
So, what's wrong with mine?
I used CD4046, while the layout mentions HEF4046's. Might that be the problem? Hmm.
Is it possible too tie all your digital grounds together, including the filter capacitors for the digital supply, then make one connection to signal ground? You may not get 100% elimination of clock signal with breadboard, but it would be interesting if you could reduce it greatly.

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box
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Post by box »

Reachahighernoon wrote: 03 Apr 2022, 08:33
poulto wrote: 03 Apr 2022, 07:47 Does anything like this exist on the market? I'm looking for this exact effect - it looks like it's pretty much a BBD chorus pedal that spilts the highs and lows and gives a similar effect to a Leslie speaker... And I want it this way because I want to plug it into a guitar or bass amplifier, as opposed to using it as a speaker sim itself.
Is anyone offering these or anything like them commercially?
I searched high and lo for an existing PCB for this type of effect and I have found nothing so far, sorry
Hi,
I did like this effect,




and choral just for fun:

Best regards,
box

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