Author Topic: Syntherrupter - A Feature-rich, Polyphonic Interrupter  (Read 7985 times)

Offline Max

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #80 on: August 30, 2020, 10:21:38 PM »
Good evening,


@Hydron: Thank you for the suggestion! I never really considered them but they do look quite powerful! Immediately ordered a couple.

Now considering my progress over the last days... I'm getting somewhere but I still do not like it. I have the feeling that I'm very far away from "KISS" and it hasn't got easier to debug. At the moment I have some kind of overflow issue when the Syntherrupter receives A LOT of MIDI data. Haven't found the reason yet.
I thought I'd create a more powerful code base but at least for now the "new possibilities" vs "complexity, efficiency" tradeoff does not look right to me. Considering efficiency: It bugs me that I can't do more in hardware; I feel like I'm not using the full potential of my microcontroller. At the moment I'm thinking about how I could use the tons of RAM this microcontroller has (256kB)... Does anyone know some good sources about synthesizer? There must be better ways to do it than what I'm currently doing...

Long story short it will be quite a while til the next update. Therefore I updated the first post in this topic, the GitHub Readme, and the v3.1.1 release notes with a big warning at the beginning. Maybe there will be a v3.1.2 disabling simple mode - just in case. What do you think?


Kind regards,
Max

Offline Max

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #81 on: September 01, 2020, 03:56:20 PM »
Admitted, that didn't take nearly as long as I thought.

What's the easies way to get rid of a bug? Rewrite from scratch. In this case I replaced the array of MIDI notes by a doubly-linked list. Note-array-related bug gone  8) (And efficiency inceased)

More interesting: I pretty much solved the issue with the audio quality. I thought I'd generate the tones in a smart way, but actually it didn't have any advantages over the most basic way to do it. Only the disadvantage of worse audio quality. Long story short: tone generation got simpler, faster, better  ;D
As TMaxElectronics commented: "now it sounds more like mine". Although you'd need at least six of those...

Since the code is stable enough to pass my MIDI torture tests, I'll verify the output signals with my scope in the next days; the final step before the next release. At least that's what I hope.

(The sceptical thoughts of the last post remain; I think quite a few things could be done better, just don't know how. But for now, we're back to "good enough" ;) )


Kind regards,
Max

Offline Max

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #82 on: September 03, 2020, 08:35:29 PM »
There's that stupid forum game, "how many posts can you write without someone else posting inbetween"...  ;D Just kidding, everything is fine. Before anyone feels criticized, I really appreciate the resonance I got here! I don't know if anyone remembers v1 but look how far we've come since then. That wouldn't have happened without your input, tank you!

But wait, there's more. The actual reason for my tripple post is the release of v4.0.0. Yes I do feel confident enough to release it. While I haven't found any new bugs, there might be a ton of them hidden in some dark corner... This code simply has not the tens of hours of testing and evolution behind itself as the old one but we'll get there.
Additionally, there's the issue with my scope... I wanted to verify the duty limiter and all I got was this. Long story short, I verified it via the average voltage function which looked like it worked correctly and actually with the brightness of the LED which is a pretty good indicator whether the duty changed or not. However I don't consider either one as truly reliable test. It looks like it works - no more, no less.

As always, the release notes contain all the changes I could remember, you should read them  :)

Edit: It helps to attach the scope pictures... Look what happens with the duty displayed in the bottom left corner. The signal is only slightly shifted such that the pulse at the left leaves the screen.

... the forum gives me an error because the pictures are ".jpeg" instead of ".jpg"? Really...? ??? Oh and, yes, when you get an error like this, anything you've written (or modified) is gone. If I'm already on this tangent, it would be nice if the forum was capable to upload pictures before posting instead of displaying "Invalid attachment" in the preview. Aaand the "(Insert Attachment x)" only inserts the text "[ attachment=x ]" without the "[ /attachment ]". After hitting "preview" it will be added at the end of your post instead (you might have seen this with some posts here, which have  or other bbcodes at the end).


Kind regards,
Max
« Last Edit: September 03, 2020, 09:25:53 PM by Max »

Offline Hydron

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #83 on: September 04, 2020, 01:30:41 PM »
I'll help break it up then :P

I wonder if the scope is looking at the duty cycle over a single period (as if it were a PWM signal) rather than the full screen, in this case probably the first full period from the left of the screen.
In the 4.7% case there is a big gap from the first pulse to the next, whereas in the 18.2% case the gap is pretty small in comparison. If the scope is looking at the width of the first pulse from the left then comparing it to the width of the following low period then you'd get wild variation in "duty cycle".

Offline Max

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #84 on: September 04, 2020, 03:36:02 PM »
@Hydron: That makes a lot of sense! Thank you.

(Rather) quick note about ADSR: there are still two features missing (a useful editor aside). First it is not possible to define a meaningful release datapoint if the previous datapoint has already a target of 0 (that's because the calculations base on the differences between two data points). For any other datapoint this is not a big deal; its target value has already been reached with the previous point (effectively will be skipped). However a release can occur at any time. Not a big issue, just letting you know I know it's there :) The other missing thing is defining whether a datapoint is affected by the note velocity or not. Currently the velocity is handled like volume and scales the whole curve, but that's not right. Will be an easy fix though.

I thought it would be helpful to create a diagram about what n-tau actually does. Here it is. You can see how it affects the curve and clearly you can see where the datapoints are ;)
Edit: This is btw real data from Syntherrupter, read with the debugger. "None of that CGI rubbish!"


Best regards,
Max
« Last Edit: September 04, 2020, 04:10:04 PM by Max »

Offline Max

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #85 on: September 07, 2020, 01:10:01 AM »
Good evening,


I got my ESP8266s convinced to organize themselves in a meaningful way such that the whole lightsaber thing will be pretty much plug&play. If you want x lightsabers you buy x+1 ESP8266s and flash them with the same firmware. One of them will be connected to Syntherrupter and act as receiver, the others will be sitting in the lightsabers and send data to the receiving ESP.
You'll have to assign a number to each of the sending ESPs so that Syntherrupter can distinguish the lightsabers and that you can select which lightsaber plays on which output. To do this you connect them to Syntherrupter instead of the receiving ESP, and set the number you want. The ESP will save the value in its flash.
After this initial setup it is as easy to use them as possible. Simply power them up; order doesn't matter. They'll find each other and connect. They'll also determine themselvers whether they are sender or receiver (since only senders are connected to an IMU).

So far so good I think. There's only one "issue" I'm not sure how to solve. I'd like you to be able to flash those ESPs without downloading the Arduino IDE and the whole Arduino ESP stuff. It's not difficult but I think it's a complete overkill for flashing binaries once (bugfixes aside, those things won't need any updates since the whole data processing happens on the Tiva microcontroller).
The Arduino IDE has the option to export the binary file so I thought there must be a way to flash this binary?

In case anyone is interested, here's the Arduino source.
It's been a loooong time since I did Arduino stuff the last time so there're likelythings that could be done better.

Edit: Ok I found out that there‘s a Python script from Espressif. This is already better than the whole Arduino IDE. If someone has a better option, please tell me. Oh and if a user already has to have Python installed, I could as well write a Python script for the Nextion firmware update. Then you wouldn‘t need the Nextion Editor.


Curious to hear your thoughts!
Max
« Last Edit: September 07, 2020, 10:05:48 AM by Max »

Online Mads Barnkob

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #86 on: September 07, 2020, 09:13:15 PM »
Hey Mads,
Yes i quickly designed it in EasyEDA. My previous interrupter was a mess, and i actually even fried it because of it. So i wanted a clean build with minimum wires, hence a PCB was born :)
I added some extra headers to connect some switches for safety and LEDs for indication.

Ordered from JLCPCB, it had arrived in a few days :)

I liked this idea so much that I wanted to use it on my own controller, with some more switches between regular analog interrupters and the syntherrupter and I also added the option to turn on a buzzer for no-tesla-coil-plugged-in-testing instead of just looking at LEDs.

Any apparent errors before I etch it?



I will go for fiber, despite the fine work Max is doing on bringing in a ESP8266 wifi module based solution, I want to keep this controller as failure proof as possible. Which is why it will also have analogue interrupters built in.
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Offline Max

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #87 on: September 08, 2020, 02:14:32 AM »
@Mads:
For <100mA a TO220 MOSFET seems like an overkill to me...? Or are they cheaper than standard TO92 BJTs? I somewhat doubt that since you’d need the logic level version of the MOSFETs.
I don‘t really get how the SW7-12 will be wired. Jumpers on the board...?
The buzzer header is connected via resistors to 3.3V. How/where do you connect the other end of the buzzers?

The ESPs were never intended for replacing the optical outputs. The idea was that you 3D-print yourself a nice Star Wars lightsaber, put a battery, IMU, ESP8266 in it and get the well known lightsaber sound from your tesla coil(s) when moving the lightsaber.

Here‘s a first „proof of concept“ video. Sound effect isn‘t great but that aside the new mode is already well integrated and works as expected. It is possible to connect up to 4 lightsabers to Syntherrutpter.
If anyone knows a reasonable „IMU to lightsaber effect“ code, I‘d love to hear about it! Code shown in the video cam be found here. It is pretty basic (ignore the stuff commented out).


Kind regards,
Max

Online Mads Barnkob

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #88 on: September 08, 2020, 08:27:32 PM »
@Mads:
For <100mA a TO220 MOSFET seems like an overkill to me...? Or are they cheaper than standard TO92 BJTs? I somewhat doubt that since you’d need the logic level version of the MOSFETs.
I don‘t really get how the SW7-12 will be wired. Jumpers on the board...?
The buzzer header is connected via resistors to 3.3V. How/where do you connect the other end of the buzzers?

The ESPs were never intended for replacing the optical outputs. The idea was that you 3D-print yourself a nice Star Wars lightsaber, put a battery, IMU, ESP8266 in it and get the well known lightsaber sound from your tesla coil(s) when moving the lightsaber.

Here‘s a first „proof of concept“ video. Sound effect isn‘t great but that aside the new mode is already well integrated and works as expected. It is possible to connect up to 4 lightsabers to Syntherrutpter.

I just use the same foot print for TO-220 and TO-92, they got plenty long legs to fit that width and its also to give myself some more room since I etch the boards myself, so there is no reason to go for thin as possible for me :)

The idea with SW7-12 headers is that this board just routes between the syntherrupter, the normal interrupter and the switches, so I can have it all put together with pin header plugs (to avoid that large spider web of soldered together boards). The switch would just be a NO-C-NO so the signal back to the optical board is on C and each interrupter on a NO.

The buzzer/speaker is driven along with the optical transmitter, the SW marking near it is the other end for the buzzer/speaker.

The light saber idea is brilliant! I mistook it for being a call-name for a wireless connection due to Hydron mentioning that :) 
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Offline Max

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #89 on: September 08, 2020, 11:20:43 PM »
Quote
I just use the same foot print for TO-220 and TO-92, they got plenty long legs to fit that width and its also to give myself some more room since I etch the boards myself, so there is no reason to go for thin as possible for me :)
Assumed something like that. The main reason for brining it up was that usually TO-92 pinout is CBE (SGD for MOSFET) instead of BCE/GDS for TO220.
Okay if the plugs make sense it's fine. I guess I'll have a better idea of it once you've build it.

Quote
The light saber idea is brilliant!
Remember, it's not from me but from Netzpfuscher :) But I agree 100%. I thought the same thing when he showed me his prototype.

Speaking of prototype, as my video in the last post showed, the Lightsaber feature already works. After a little bit more tweaking I thought you might want to play with it, too.
Here you go, a new beta to play with. Beside the lightsaber mode I also started to document the whole thing. While at the beginning Syntherrupter was made of two parts plus transmitters it is getting more and more complex.  For now the documentation contains schematics, lightsaber wiring diagram, lightsaber how-to and data sheets. I'll fill it more and more and in the end it will hopefully become a useful wiki.


Best regards,
Max

Online Mads Barnkob

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #90 on: September 10, 2020, 03:07:25 PM »
Quote
I just use the same foot print for TO-220 and TO-92, they got plenty long legs to fit that width and its also to give myself some more room since I etch the boards myself, so there is no reason to go for thin as possible for me :)
Assumed something like that. The main reason for brining it up was that usually TO-92 pinout is CBE (SGD for MOSFET) instead of BCE/GDS for TO220.
Okay if the plugs make sense it's fine. I guess I'll have a better idea of it once you've build it.

Thanks for reminding me, I could have fooled myself in the hurry there!
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Offline Max

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #91 on: September 21, 2020, 02:59:47 PM »
Hello everyone!


Finally I created an ADSR Editor. It is not the most user friendly but it does the job. Additionnally the new ADSR structure introduced with v4.0.0 allowed an easy yet powerful extension: loops! A random example of ADSR loops can be seen here (at 08:50): https://www.youtube.com/watch?v=1p675bxQwFg&t=8m50s
Edit: As a starting point for playing around, here are the values that (more or less) reproduce the sound from the video linked above. Note how step 3 links back to step 2, creating a loop.
Step  |  Next Step  |  Amplitude  |  Duration [ms]  |  n-tau
1
2
1.0
500
2.0
2
3
0.0
200
2.0
3
2
1.0
100
-2.0
8
8
0.0
100
2.0

Since editing envelopes with this editor is already hard enough, it would be good if you could save the curves, right? While programs 0-19 will always be the same at startup, programs 20-39 are stored in EEPROM. So you can create and save 20 custom programs. You can also edit the programs 40-63, but the changes will be gone after a reset or power cycle.

Third, minor change: increased ADSR step count to 8. Allows more complex envelopes

All of this has been released as v4.1.0-beta.2

Edit 2: Just a quick reminder: you can keep MIDI Live mode running in background while you have the ADSR Editor opened. This means you can listen to your modifications without leaving the ADSR editor 8)


Kind regards,
Max
« Last Edit: September 21, 2020, 09:27:25 PM by Max »

Online Mads Barnkob

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #92 on: September 25, 2020, 08:26:52 PM »
Forgive me for not knowing enough about MIDI or ADSR.

Is the purpose here that you can take any "simple" MIDI file with just plain notes and then these loops are added on each note or how does it really work?

I wish I had more free time on my hands, you get out revisions of the software faster than I can even get the hardware out of the box ;) (making videos out of projects does however slow down things a bit)

Keep up the great work!
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Offline Max

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #93 on: September 26, 2020, 01:14:47 AM »
Hi Mads,

I guess a simple google search would give you a faster and better answer but since you asked here I feel like I should try to explain. So MIDI is a digital format. It does not contain any analog information like waveforms. If you press a key on a keyboard it sends a "Note on" command, which contains thee informations: the channel, a number indicating what key you pressed, and a velocity that says how hard you pressed the key. That's it. If you release the key, same thing. "Note off" command, containing the note number that's turned off and how fast you released the key. So basically all the synthesizer gets during playback is when a note starts and when it ends. That's what i would call the "core" of MIDI. Almost all the other stuff is about giving the syntheziser more information about how it should form a meaningful sound. F.ex. the "Program" command tells the synth what instrument it should sound like. Program 0 is "Accoustic Grand Piano", Program 12 is "Vibraphone" etc. Again, this is just a number, not more. The actual sound still has to be generated by the synthesizer itself.
Now what are those MIDI "channels". Imagine you have not only one instrument, but 2, 3 or more. The guy with the drums doesn't want to sound like a vibraphone, right? So you have to distinguish them and that's what the "channel" indicates. Each instrument will be set to a different channel and the synthesizer will know what data belongs together and what not. So usually 1 channel is 1 independant instrument. MIDI supports up to 16 channels.

Now let's talk about ADSR. We know that the synth has to generate the sound from scratch since MIDI doesn't contain any actual sound. What characterises a sound is its amplitude and its frequencies. On an analog synth you would mix multiple waveforms together to get different harmonic content. This is what makes a piano sound different than a flute - even if both play the same note. Additionally there's the amplitude. If you look at an audio sample in a program like audacity you'll see a certain shape. Rising at the beginning, falling at the end - in very basic terms. If you zoom in closer you can see the actual sine wave(s). If you zoom out, you can see the overall "outline", called envelope. This envelope can have any form, but a very good approximation is to distinguish 4 parts: attack, decay, sustain, release. If you have no picture in your head, google is really the best option. A pic or even a short video really say more than a thousand words.
Here's an example: Think of a violin. You can play it in many different ways. If you play it with the bow, you start and stop rather slow. It is soft. However if you pick it, you get a sharper, short sound. In ADSR terms: the bow has a slow attack, that is not much higher than the sustain level, and a slow release. However the picking sound has a very fast attack, and it always drops back to 0 - rather quick, too.

Since we can't really control the harmonic content of a regular DRSSTC (the interrupter signal will always be a low duty, digital square wave), the envelope is the best option to change how the music sounds. Usually an interrupter plays a note at a constant ontime a "note on" command turns the output on, a "note off" command turns it of, no more. But as I just explained, the envelope of normal instruments is nowhere near of being constant. And that's what the ADSR feature allows you to do. Change the run of the amplitude after a "note on" or a "note off" command. You want a bit of an echo (not quite but something similar), increase the release time. The note won't stop right at the moment you release the key, but drop slowly back to 0. There're endless possibilities what shapes and patterns you can generate with this. And as I said before, I'm sure pretty much any youtube video about ADSR gives you a better idea than this ;)

Talking about fast revisions? Okay, here's another one  ;D But this time no really big news. Check out the release notes for more details: https://github.com/MMMZZZZ/Syntherrupter/releases/tag/v4.1.0-beta.3
What I can reveal is that it finally allows a more realistic piano ADSR curve. Try the following if you want:
Step  |  Next Step  |  Amplitude  |  Duration [ms]  |  n-tau
1
2
2.0
15
2.0
2
3
1.0
100
2.0
3
3
0.0
8000
7.0
8
8
0.0
200
4.0


Kind regards,
Max
« Last Edit: September 26, 2020, 01:20:24 AM by Max »

Offline Max

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #94 on: September 27, 2020, 12:52:36 AM »
Bugfix release. Details in the notes. https://github.com/MMMZZZZ/Syntherrupter/releases/tag/v4.1.0-beta.4

Kind regards,
Max

Offline futurist

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #95 on: September 27, 2020, 12:24:20 PM »
Hi Max

I couldn't test the coils during summer because of the neighbors >:(, then I found a suitable place in abandoned industrial complex and I borrowed power from a guy who has a workshop there
I'm only at home at weekends, however last 4 weekends it was either rainy or windy. Yesterday I finally managed to test the interrupter on my bigger coil and I ran into a few problems

I set coil limits to 300 us and 10% PWM
I'm still not familiar with volume setting on MIDI live and I couldn't figure out what each of the option does. I changed only on-time, didn't touch note PWM setting. However changing on-time didn't behave like changing on-time on my onetesla interrupter for some reason. I didn't have enough time to bring the oscilloscope and to examine what is exactly happening

Most of the midis played sound very nice, I couldn't record all of them so here are two short clips


Some songs sound bad because of (I presume) PWM limiter, it sounded like the note is "chipped". In super mario theme it's not that bad, but it can be noticed if you listen closely

At one point the coil made loud "pop" sound and it blew the 16A fuse. I quickly tried to shut down the midi playout but I then saw that the interrupter has crashed


I was sure that IGBT died because of how the coil sounded when it blew the fuse, but luckily it didn't. OCD or UD+ pulse limiter probably saved the coil
Sorry for sparse write-up, ask if I forgot something  :)

Offline Max

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #96 on: September 27, 2020, 02:02:53 PM »
Hi futurist,


Abandoned industrial complex sounds like a great testsite! Congrats!
Edit: The MIDIs do indeed sound good. They seem to be rather "simple" MIDIs, right? Tipp: Repetitive notes (without delay inbetween) are very hard to distinguish from each other when you do not use ADSR. This is especially audible at the beginning of the first video. For a start you could try program 1. Very basic, no surprises, except for that it is less loud. It also reduces the issue with the duty limiter a bit.

With 300us ontime you reach the 10% duty limit very fast - in many cases with already 1 note. That explains why the duty limiter has been active so often.
I‘m very curious to hear what you mean with „changing on-time didn‘t behave like [expected]“!
I gave my best to explain the „Note duty“ slider and what it does compared to the „Note ontime“ slider in the following post: https://highvoltageforum.net/index.php?topic=1020.msg8564#msg8564
hope it helps you!

I‘m very sorry for the crash you had to experience. And even more relieved that your coil survived!
Since you write you wanted to turn off the outputs - was that a reflex action or was it actually still generating an interrupt signal?
The bad news is: I’ve never seen that error code on a Nextion display nor could I find anything about it. But that might not be important, because I don’t think the Nextion display is the origin: the loud bang indicates that the Tiva microcontroller crashed. It‘s unlikely that the nextion screen caused a a true crash of the microcontroller and any „normal“ fault condition would not cause the output to stay high.

tl;dr
1. I won‘t be able to investigate the issue because I still have no test place for my tesla coil.
2. since the crash seems to have happened on the Tiva microcontroller, I suspect the external powersupply and/or the USB cable to have picked up EMI from the tesla coil.
3. Just a random thought: If your USB cable has too high resistance, it could cause the voltage to be much lower than 5V. 4x60mA for the transmitters plus 500mA for the touch screen is a decent amount of current. You should check that with you scope.

Out of curiosity: what firmware were you using?


Kind regards,
Max
« Last Edit: September 27, 2020, 02:44:40 PM by Max »

Offline futurist

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #97 on: September 27, 2020, 07:49:49 PM »
Sorry I completely missed your post about note duty limit, makes sense now

Quote
I‘m very curious to hear what you mean with „changing on-time didn‘t behave like [expected]“!
It seems that spark length is not changing as linearly with on-time like on my old interrupter, but it could just be my personal view

Quote
Since you write you wanted to turn off the outputs - was that a reflex action or was it actually still generating an interrupt signal?
The coil continued to buzz, I panicked a little after I saw that the interrupter has crashed. I don't know why UD+ UVLO didn't trigger. All LEDs turned on, a pity I didn't record it.. very strange

I doubt it had anything to do with EMI, laptop and interrupter were far away and USB cable is short and shielded. Also I'm only using one output, so current shouldn't be a problem
I was using latest firmware

Do you think I can set duty limiter to 15-20%?

Next time I'll test two coils at once, does someone have MIDI files for playing on two coils simultaneously?

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #98 on: September 27, 2020, 10:44:43 PM »
Quote
Since you write you wanted to turn off the outputs - was that a reflex action or was it actually still generating an interrupt signal?
The coil continued to buzz, I panicked a little after I saw that the interrupter has crashed. I don't know why UD+ UVLO didn't trigger. All LEDs turned on, a pity I didn't record it.. very strange

I doubt it had anything to do with EMI, laptop and interrupter were far away and USB cable is short and shielded. Also I'm only using one output, so current shouldn't be a problem
I guess you're using a SMPS for the UD+? At least my Meanwell SMPS is able to maintain it's output for a few seconds even with two relais and the UD+ drawing current.
What LEDs do you mean? I can't see LEDs on your Syntherrutper so I guess you talk about those connected to the UD+? Which wouldn't be that surprising; although it's no real help either.

That's very strange indeed. Since it continued to buzz the Tiva microcontroller did obviously not crash* but then remains the question what happened.
A word about the error screen you saw. It is not part of my firmware. Its part of the Nextion bootloader, which runs my firmware. Usually you see a bootloader message only when there's no firmware, a corrupted firmware, or during a firmware update. But if the firmware has been compiled successfully and uploaded successfully, it shouldn't appear. Hence I've never seen that error, and I haven't found anything about it. I assumed that when the Tiva microcontroller crashed it sent a ton of gargabe to the Nextion, causing that one to crash, too. But since you say the microcontroller continued to operate, that makes not much sence anymore. Like the rest.

So here's the only other thing I can imagine to have happened. For some reason the Nextion screen crashed, and sent garbage to the Tiva which caused unexpected behavior. I don't see how but it's at least something I can test quite simply: send total garbage to the microcontroller and see if the output glitches or not ("fuzzing").

* Why do I think it did? The ontimes themselves are generated in hardware, meaning a timer is started that runs for the exact amount of microseconds we want. It's configured as oneshot, meaning it does this once and then stops. Additionally it's configured to set the output pin to high when it starts, and back to low when it stops. So as long as the timer module is still provided with a clock signal the ontime should definitely end after the specified amount of microseconds, not later. Once the program enables the timer, it runs completely independant. Interrupts, faults, etc they do not affect the timer in any way. Hence I thought the microcontroller crashed, because that's the only explanation I found that would stop the timer from running.
A single ontime is just a "pop" sound, but since you say it "buzzed", the microcontroller must have been actively generating new ontimes (remember, it's a oneshot timer, it has to be started by the program for every single ontime). This does not happen after a reset. This does not happen after any kind of fault condition. This only happens when it continues to run the code.

Do you think I can set duty limiter to 15-20%?
Probably yes. Here's what I'd suggest. Increase duty step by step (5 percentage point steps sounds reasonable) and keep an eye on the temperatures, maybe on the current consumption, too. As long as nothing gets too hot or fries something like the input rectifiers (or the fuses) it should be no problem to increase the duty.

Next time I'll test two coils at once, does someone have MIDI files for playing on two coils simultaneously?
Well... I posted a Popcorn MIDI (click) in this thread and a Thunderstruck MIDI (click again). Both have multiple channels that are suited for playing on tesla coils. I'd suggest to play around with the channels; which go better together (same coil) and which are better separated (different coils). Additionally you can even play a single track on two coils using the stereo features. F.ex. you could assign the channels with the bass line to one tesla coil, fully using the low frequencies for some pulse skipping, and the melody on the other coil, producing intense, high BPS streamers.
Just as a reminder: almost every MIDI file I have in my collections, any files I ever used for a demonstation are unmodified MIDI files from the internet. Except if you consider a change of the instrument as a modification. Nothing else is needed in 99% of the cases. Additionally I linked to a couple pages with really good MIDI files a few posts ago (click. you're welcome). Look for anything that appeals to you and try it out. Since you don't have to modify anything, downloading and testing costs at most a few minutes. I do think that Syntherrupter makes it easy to try random MIDIs.
Admitted, the stereo features mentionned above do need a few extra commands which you have to enter with the MIDI Editor on the touch screen (proudly presented by me over here). But even that becomes a matter of a minute at most once you've done it 2-3 times. And if you found the settings you like, you can include them at the beginning of the MIDI file for future playbacks. No idea what I'm talking about? No worries, the ACDC Thunderstruck MIDI already includes them. Just remember to enable stereo playback for both of your coils ;)


Kind regards,
Max

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #99 on: September 28, 2020, 09:52:47 PM »
I guess you're using a SMPS for the UD+? At least my Meanwell SMPS is able to maintain it's output for a few seconds even with two relais and the UD+ drawing current.
What LEDs do you mean? I can't see LEDs on your Syntherrutper so I guess you talk about those connected to the UD+? Which wouldn't be that surprising; although it's no real help either.
LEDs on UD+ and precharge controller, really strange. It all happened in a few seconds in the dark, so I didn't catch every detail. Next time I'll setup camera to record the whole test

That's very strange indeed. Since it continued to buzz the Tiva microcontroller did obviously not crash* but then remains the question what happened.
A word about the error screen you saw. It is not part of my firmware. Its part of the Nextion bootloader, which runs my firmware. Usually you see a bootloader message only when there's no firmware, a corrupted firmware, or during a firmware update. But if the firmware has been compiled successfully and uploaded successfully, it shouldn't appear. Hence I've never seen that error, and I haven't found anything about it. I assumed that when the Tiva microcontroller crashed it sent a ton of gargabe to the Nextion, causing that one to crash, too. But since you say the microcontroller continued to operate, that makes not much sence anymore. Like the rest.
I think we have to pretend it didn't happen until I test the coils again, with oscilloscope and camera to catch any problems

Do you think I can set duty limiter to 15-20%?
Probably yes. Here's what I'd suggest. Increase duty step by step (5 percentage point steps sounds reasonable) and keep an eye on the temperatures, maybe on the current consumption, too. As long as nothing gets too hot or fries something like the input rectifiers (or the fuses) it should be no problem to increase the duty.
I'm curious what was max. duty cycle with my onetesla interrupter turned to 300us max. on-time. I think I'll hook it on the oscilloscope and measure, I wouldn't be surprised that it's around 20% for MIDIs like popcorn. SKM400 halfbridge was barely warm with onetesla interrupter on max., MMC is overkill for this coil and is always stone cold. I blew few 16A fuses with the final countdown song solo part


Can't wait to test the stereo feature!

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Re: Easy to build Polyphonic MIDI Interrupter
« Reply #99 on: September 28, 2020, 09:52:47 PM »

 


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