The issue with the single power cable can be solved in two ways:
- You use a single supply but connect the grounds of the circuits only in one place (at the supply) and possibly insert some filters in each power rail (large capacitor + choke) to prevent any digital noise from getting into the pedals. Then you have only a single low voltage wire going into the box. That would be the preferred solution.
I must say that the idea of adding a filter every time I add a pedal discourages me a lot, but it does not guarantee me to solve the problem.
Anyway, a single power supply would be the solution I prefer in absolute and is what I currently do in this way
http://guitargearfinder.com/wp-content/uploads/2017/03/guitar-pedals-daisy-chain.jpg
and at the moment in the daisy chain above, I have ONLY the first cable with the + and - that connect to the board containing Arduino, while on the other connectors i removed the ground, significantly reducing the noise of ground loop: what remains is very normal.
Trying to put the first connector on an analog pedal and a cable with only the ground on Arduino, the noise becomes infernal
But, as I wrote, with the power supply above everything would be ok until the wah wah switch turned on, otherwise I have this sound ticking
https://instaud.io/_/1wlF.mp3
Instead, the power supply I use in this video consists of the two AC-DC converters and I show the noise generated as soon as the wah wah is inserted
https://streamable.com/hozsj
If would actually help if you could draw a diagram how is everything wired together because I am starting to suspect we may not be talking about the same thing.
Now i have the certitude that i will not use chinese bucks because i do not trust myself, so in alternative i would have:
1) https://ibb.co/d984kG
2) https://www.amazon.com/Truetone-NW1-1-Spot-Adapter/dp/B0002GZLZQ
The first, if i want to keep it together with the pedals, is fine if i put the mumetal under the wahwah as in the video of my first post or, without mumetal, if i keep it away from the pedals.
The second is sensitive to the TAC TAC TAC of Arduino and if with the mumetal also disappears the TAC TAC, then i prefer it to the first because at least it is certified since the first is a do-it-yourself. How do you suggest me to do?
If would actually help if you could draw a diagram how is everything wired together because I am starting to suspect we may not be talking about the same thing.
https://www.photobox.co.uk/my/photo/full?photo_id=500345703815
This diagram refers to the second power supply (1Spot). The ground only on the first pedal and the other the ground comes from the signal cables.
That link doesn't display - it redirects me straight to the Photobox front page.
I don't know your voltage and current requirements for the entire setup
.....
But if that Truetone adapter works, why not. On the other hand, they don't list any FCC/UL certifications, nor any specs whatsoever on their website, so their adapter could well be a cheap supply from Shenzen with a Truetone sticker on it ...
The mumetal shielding will certainly not fix that tap-tap noise - that is most likely being carried by the wiring, not radiated (which is the only thing that a metal sheet can fix). The video where the guy has used the mumetal sheet was fixing a mains hum from a 50/60Hz transformer under his pedal, not a digital noise.
- If the Arduino is still causing trouble, put it on a separate power rail - that could be simply a separate pair of wires to the power connector with a choke and a few capacitors next to the Arduino
- If you still can't solve the above and you want to use the linear supply with a transformer, try to find a toroidal one
2) https://www.amazon.com/Truetone-NW1-1-Spot-Adapter/dp/B0002GZLZQ
That link doesn't display - it redirects me straight to the Photobox front page.
Very strange, if I click on it works for me. Try this
but I would use it for the same reason as the video adopting the power supply https://ibb.co/d984kG, although I imagine it will not work with digital noise. I would put the mumetal sheet under the wahwah, in what sense do you speak of a shortcircuit ?
I powered Arduino separately in two ways:
Initially I did not think about the toroidal, otherwise I would have opted for that, but for now I do not want to spend any more money, and if I do not resolve in any way use this https://ibb.co/d984kG and keep it away from the pedals.
So you have decided to distribute only the +9V and the return path is over the shields of all that signal wiring
through the USB shield & the Arduino back to the power supply? And you are wondering why are you having weird noises in the signal? If you have used the star grounding system, each device would have its own power and ground wire back to the supply.
You definitely do need to rewire this...
However, I would still rather replace the supply with something that is hermetically sealed and professionally made, whether that TrueTone adapter of yours or another one. That homebuilt supply of yours is a problem waiting to happen. The linear voltage regulators will get hot in the plastic box...
If some drunkard gets fried because they have spilled beer in your kit ...
...using a good used bench power supply, like HP or Power Designs.
OP said he did not want to use a separate supply because he is afraid he would forget it.
If you have used the star grounding system, as not the source of the injury. In many countries you have no right to do anything with mains unless you are a licensed electrician.
I believe you are doing MIDI control of the Zoom G3 with the Arduino and MIDI happens to have an Active Sense message sent every 300ms to detect whether the device didn't get unplugged. Guess what is the period of those tap-tap noises in the MP3 file you have linked before. Yup, every ~300ms ...
If you have used the star grounding system, as not the source of the injury. In many countries you have no right to do anything with mains unless you are a licensed electrician.
To have a single point of reference for the ground, i could try to put in the mammut the grounds instead of the positive, that is to reverse the connections. What do you think about it ?
Let me understand, would Arduino send a periodic impulse that has a period of 300 ms? But with the software I can not inhibit it in sending this impulse? Change some libraries ?
Some time ago I had kept the home-made linear power supply switched on for more than 2 hours to check the temperatures with a thermometer on the two 7809 regulators and it did not exceed 45 ° C, if this is the problem.
...I am not quite sure what are you referring to as "mammut". Is that a slang for some sort of a terminal strip?
...For the signal cables between the devices - use a shielded cable and connect the shielding to ground only on one side.
...The way I would wire your setup:...
- The output to the amplifier needs to have both signal and ground connected because it needs to get the reference level - run a ground wire from the connector to your common grounding point again.
45C is okay, but the rest about your supply still applies. That's not a supply that will withstand the rigors of portable use.
yes, mammut is properly a terminal strip.
From what you write, if I understand correctly, I deduce that I can use two terminal strips, one for the positive reference and the other for the negative reference. But if the chassis on which the pedals are fixed is made of aluminum, like this https://cdn.marcmart.com/ebay/EC916/3.jpg, could not i drill a hole and make all the ground converge here ? Or do you say that there is some impropriety and better to use two terminal strips, one for the positive reference and one for the negative one ?
45C is okay, but the rest about your supply still applies. That's not a supply that will withstand the rigors of portable use.
Why do you say this ? what problems could I go to?
Today the postman gave me the sheets of mumetal and placing them under the wah wah the hum of 50 Hz or 100 Hz disappears. I remember that the hum is generated when I use the power supply with the transformer putting it under the pedalboard together with the pedals. Now I have to try the power supply of Truetone with the star connection of the grounds.
You don't have to drill a hole into chassis....Just make sure the chassis is insulated from the pedals...
You can still use two terminal strips, one affixed directly to the chassis for the ground and one for the 9V.
See my comments about the lack of any mechanical support for the components...
Then there is the issue of the mains wiring (lack of fuse), the possibility of water/liquid ingress due to the holes you have made, etc.
Yes, don't leave it like that, happy that the transformer hum is gone. The current wiring will certainly cause you problems in the future.
I do not know what you mean by mechanical support but the pcb is fixed on two wooden slats through 3 screws
I drilled the holes because I did not find an enclosure of adequate size with provision for ventilation, even if I would not use for more than 3 hours at most and the temperature does not exceed 50 ° C
By chance do you refer to the wiring without the star connection of the grounds ? In this case, if the star connection solves the problem, it means that I will use Truetone's power supply
What I mean is that the large components need to be mechanically secured to the PCB/box as well, not only soldered...
I mean the wiring you had in the hand-drawn diagram with the only ground connection through the Arduino and the USB shield.
What I mean is that the large components need to be mechanically secured to the PCB/box as well, not only soldered...
Ah ok, the regulators are fixed with a screw to the respective heatsink but often I have seen the heatsink anchored only to the pcb, like mine. To fix the big capacitors, actually some hot glue can put it. About the main wire, not finding a strain relief in my drawers, I opted for a tripolar panel plug like this https://tinyurl.com/y8wrdave but if everything works I'm going to get a smaller enclosure with ventilation and to add a strain relief.
I mean the wiring you had in the hand-drawn diagram with the only ground connection through the Arduino and the USB shield.
Anyway, in a few days I will dedicate myself to "the star", and I hope to resolve definitively
For the signal cables between the devices - use a shielded cable and connect the shielding to ground only on one side.
For the signal cables between the devices - use a shielded cable and connect the shielding to ground only on one side.
Inside each pedal effect the shielding of the signal is connected to the ground of the power supply, so to realize what you say I have to open the pedal and disconnect all these shielding from the ground of the power supply, leaving it connected only on the first or last pedal. Do you confirm this ?