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BOSS CE1 PROJECT: MN3002 or TDA1022P: DOC UPLOADED

Started by drog_trog, March 14, 2018, 06:09:54 AM

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skeeter

I built ver2 and followed the diagram not connecting an extra wire to the chorus depth pot ,when I eventually connected the extra wire there was hum ,Ihave built the TDA version .With a switchmode PS there is hum with a regulated supply just a little but as was mentioned here mine sound more like a tremelo with low end thump in chorus more vibe mode is great Earlier in the year Scruffie pointed out that the voltage requirement of the respective BBD's is very close but not identical. In most cases it would be fine, but due to the slight variance in tolerance from one chip to the next from the same batch (similar to how a batch of 100uf capacitors can measure anywhere from 80 to 120 or the hfe of transistors vary from one to the next), there may be rare instances where one particular chip may sound like it isn't quite tuned in well enough (& no trimpot in the CE1 design to tune in the BBD). Simply swapping it for another chip would likely sort it out as it would only rarely happen within the extreme end of the range. Ideally a resistor or two could possibly be replaced with a trimpot to better take care of it so it never happens at all.
I think this  circuit does need a trim pot !!!!with a 25k intensity pot  it helps but not  a perfect chorus         


skyled

Quote from: DrBen_GE on August 27, 2020, 09:10:47 AM
My chorus   :)

How does your PCB differ from drog_trog's? I think the weak part of his is the goofy and expensive Recom power supply. I've never gotten my build to work properly. I was kind of hoping madbean would release a reliable build someday...

Ricotjuh

Now I come across this video: https://youtu.be/PCz9JyEh4Go
The same pedal can be seen here. Here too I hear a lot of noise. Is that with you too? Still troubleshooting but can't find the problem yet.

Ricotjuh

I have now taken up this project again.
I started measuring with the audio probe, but I quickly picked up noise within the pedal. And after the BBD, this noise is merged with the "effect" and you can finally hear that.
So first find out where that noise comes from. And then I immediately come to the next point that I have my doubts about.
There is an amplifier circuit around IC2. However, I am measuring a very high gain here. Namely 1.5Vpp on the input (Pin 3). And almost 30Vpp on the output (pin 1). This is a gain of 20x. This seems like a lot to me. Or is this actually necessary to get the sometimes mentioned headroom? I can also imagine that every bit of noise that is there is also greatly amplified ..
I'd love to hear what you think about it.


Ricotjuh

The gain in previous post seems to be correct.

Just took another measurement, and then you can clearly see that the supply voltages dance with the chorus / vibrato effect.
In this video is measured on Pin 8 of IC2. This is the + 14V. This is the AC voltage on the 14V. You can clearly see that the AC signal responds to the effect.
https://youtu.be/c_w-dd6nEAw

In the next video I have drawn out the time base and zoomed in further on the signal.
The yellow channel is -14V (pin 4) and the blue channel is + 14V (pin 8)
I have yet to find out where this came from. All help and tips are of course welcome.
https://youtu.be/bbjNENkb53w

RDL68

My goodness. This shrine to the origin of chorii thread is back.

Ricotjuh, after checking out that vid you found of someone selling their clone, the noise there seemed to disappear when his hands were on the strings & reappeared when he wasn't touching the strings, ie reaching for the pedal controls. It could be caused from anything from his guitar cord to his amp & anything else. I've never had that problem related to the CE1. It's a different kind of grounding problem & different noise to using the wrong type of power supply.

I recall the earlier vid you made of yours a year ago (or whenever it was) was indeed a different kind of noise & sounded exactly like the noise I was getting when I tried a dozen or so typical power supplies, including more than one which was advertised as "isolated". Only that product I mentioned I'd bought that was specifically designed to provide multiple isolated power outs for effects got rid of it for mine. Sorry I haven't been much help.

Ricotjuh

Hello .. thanks for your response.
My feeling says it is a grounding problem after all. But I don't measure crazy things in that area.
As for the power supply, I now also test with a 9V battery (2 parallel). And even then the problem continues to arise. And I can't get a cleaner power supply.

Ricotjuh

I now have new BBD chips. Also ordered PCB V2.0. I expect to receive it this week. Then rebuild the whole again. And then test again. To be continued.

mwelch

Where can I find a PCB or transfer file for this?  The build document link is dead.

JackSkellington

Indeed, I'm interesting, too.
I'd like to see the final schematic with the TDA1022.
Thanks. :)
«Just because I cannot see it doesn't mean I can't believe it»

skyled

Here's my folder with all my collected CE1 build docs and schematics. It has everything you guys are asking for and more. Just don't expect me to be able to help you since mine doesn't work right either...

https://mega.nz/file/hZsEFYZI#Upbq0Nk_dnao3xVAQvflUTQlZ5edU5aBVQXRekpmZtI

Ricotjuh

Okay, I received V2.0 yesterday.
What I experienced during my first test with V1.0 is the number of wires that need to be soldered to the potentiometers. All this has to be concealed in the rather tight housing. So I made a piggyback board that slides onto the main PCB.
I made 2 versions. V1.0 is for my own fabricated PCB. This only consists of 4 potentiometers like the original from V1.0.
But because this PCB differs slightly in terms of component placement compared to the DFX print, I also made a version 2.0.
This fits completely on the DFX print and makes it possible to apply 4 buttons, or the modified version of 5 buttons. (extra chorus depth knob). If you do not want to use this option, place the level button on the most right position and only transfer Jumpers 1.
If you do want to use the 5 button mode, then make all Jumper 2 connections and then the level knob moves down and the chorus depth knob comes to the far right.
The trim pot is still accessible.
The only wires you need to solder are the input and output jack and the 9V jack.
When I receive these, I will continue testing.

Ricotjuh

Most parts are on it. Just wait for the Bourns potentiometer and some jumpers, and then the testing can begin.