MidiStick V2.0: Next gen tesla coil interrupter

[TMaxElectronics]

I just finished a new version of the circuit board

There are no changes to the functionality, and the 20 or so old ones I have laying around are still perfectly usable, but since quite a few people are using "connector-less" opto hardware for their coils I have now added a dual footprint, that supports both HFBR and ‎IF-E96E‎ style transmitters. The only change needed is changing one resistor, as the HFBRs are rated for much higher current, and there is a slight pinout difference, that means it os not possible for both resistors to be in place simultaneously.
Oh and I have made the PCB 2mm narrower, not that that really makes a difference... 

[TMaxElectronics]

OK I have good news and bad news:

The bad:
There are two undrilled vias on the PCBs I ordered (somehow altium didn't export them... I have NO clue why that would happen).
Luckily One is only a redundant ground via, the other one however is a little more important... It carries power to the pad for the ‎IF-E96E transmitter, so that is not going to work with this PCB (I will order new ones with my next order). I can put in a bodge wire, so if somebody wants to test with that, they can but it will look bad
Everything else works fine though

The good:
I finally got some work done again

I added the ability for the devices to change their name as reported by the USB stack, so when giving the device a nickname, it will now also show it as the midi port name (after reconnecting the stick).
But this did take a little workaround because of windows foo... As somehow windows thinks if two identical USB-Midi devices are connected to a PC they must be the same and "optimizes" things by just using the name from the first for both, which causes confusion and even some midi software to just not work anymore.

The way windows checks if the devices are the same is by comparing their Product and Vendor IDs, if they match they must be identical according to uncle bill
So what I had to do was to make the PID dynamic: The PC Utility checks for conflicts (equal PIDs) between all connected midisticks, and if one is found re-numerates all devices by writing a different PID to them. I'm not sure if this is in any way compatible with the USB standard, but it works, and since I cant afford the tens of thousands of € to get certification anyway I might as well use such a workaround

So with this another item from my todo list is done, which leaves only stereo as an immediate improvement, that I want to implement.
V1.0 is coming closer and closer

Oh and I think I will have to move the aux connector... It looks so ugly and bulky hanging of the side the way it does:

[TMaxElectronics]

Oh hey, another update (finally)... I haven't really had much time working on the stick in the last few weeks, as I am putting together a new (much larger) coil and also trying to get the software for the UD3 compatible SFP module working.

I finally have stereo working, with each stick now having a setting for its stereo position, width and slope. Explaining how this affects the sound is a little hard, so just look at this picture here for explanation:

The settings basically add a scaling factor to the note volume, depending on the position of the pan knob, so (just like the synthterrupter ) you can use multiple coils at different locations and map the notes to them using the midi pan command. And with the slope and width adjustment it is easy to control stereo separation.

So for now the todo list is empty, as I didn't really get any feedback about the software yet, but since I haven't really had much time it is probably better that way

There are still some things that I want to play around with as well; mainly the midi drum channel. For that I would add a much more versatile method of sound generation, that supports fm modulation (more specifically frequency slopes), single shots, amplitude slopes, noise and probably more. At which point I'd probably have everything I need to also include a SID emulator like the one in the UD3.

But for now, I'll first want to finish my coil (about which I'll probably make a seperate post here) and the SFP module.
Here's a video of two sticks playing a midi file with some stereo mapping (with some very poor audio quality and some glitches unfortunately):

[Mads Barnkob]

Here is the first feedback!

I finally found time to not-read-the-manual, solder the opto on, plug it in, play around and make a video review about it

[Acid Byte]

very cool!
i really like to support you once you got the industrial fiber boards up and running!

[TMaxElectronics]

Thanks for the video Mads, glad you liked it
I have some things in the pipeline in terms of sound generation and effects but that is on hold until I finish my coil. Shouldn't be too long now (maybe two-three weeks), then again that is something I have been thinking for months now

i really like to support you once you got the industrial fiber boards up and running!

I'll post an update once the new boards are ready

[Max]

how unfaiiiir he got his video first 

Just kidding. Thumbs up for the video; it actually gave me a pretty good impression of how to use one. Aaand it reminds me that I should probably get that wiki done soon...

09:04-09:24 is a well deserved compliment for TMaxElectronics work!


Kind regards,
Max

[Mads Barnkob]

Thanks for the video Mads, glad you liked it
I have some things in the pipeline in terms of sound generation and effects but that is on hold until I finish my coil. Shouldn't be too long now (maybe two-three weeks), then again that is something I have been thinking for months now

Looking forward to the updates and maybe the GUI needs some kind of locking for the ADSR controls to avoid MIDI noobs like me just clicking wildly?

how unfaiiiir he got his video first 

Just kidding. Thumbs up for the video; it actually gave me a pretty good impression of how to use one. Aaand it reminds me that I should probably get that wiki done soon...

09:04-09:24 is a well deserved compliment for TMaxElectronics work!


Kind regards,
Max

The syntherrupter has become part of a bigger show controller build. I have however been waiting for deliveries from China because I was a cheap-ass on the USB connectors and some other mechanical parts Videos are in the making, but work, family and now also some additional education besides work are taking a good chunk of all the hours not spend sleeping

[Max]

The syntherrupter has become part of a bigger show controller build.

*Pressure to deliver reliable and well-documented firmwares rises* 

Considering the video(s) I want to repeat that I'm really just kidding. I perfectly understand and know how it is to have no time whatsoever or to see projects being delayed because of one delivery.


Kind regards,
Max

[Mads Barnkob]

Playing a full MIDI with 3-4 notes at the same time and half-way through it goes from edited length notes to original length. Pure abuse

Video posted at: https://highvoltageforum.net/index.php?topic=571.msg9627#msg9627

[TMaxElectronics]

Nice video I really can't wait to finally play some music on my coil...

*Keeping my thread at the top*   

guess I can do the same So just a quick update:

I ordered a new batch of PCBs from JLC on monday (100 to be exact... because it costs almost the same as buying 20 ) and they should be here in a week or so.
I also made two small changes:



The AUX connector is now rotated, so it doesn't hang over the edge anymore, and I have moved the resistors for the opto-transmitters so it is now possible to screw down the IF-E96E‎.

[TMaxElectronics]

Another short update

I received the new PCBs this week but didn't have much time to actually assemble the boards until now. That will be done tomorrow.
I also recorded some more videos of my large coil playing music this evening (again in my too small basement )

[TMaxElectronics]

Ok once again my terrible time management strikes... The pcbs and components are still next to me on my desk, not assembled as they were last weekend.
Sorry to keep those that want one waiting.

But there is actually reason for this. I have never been particularly happy with the way the stick handles ADSR, which is very un-versatile and left many things to be desired (at least for me ).
I also always missed the subtle note modifiers that give a song its character (like tremolo for example), as the sound is quite honestly a little boring without it.

To fix this I have been working on a massive code overhaul for the last few weeks (which I kind of want this to be in the version that I send out to people, hence the once again massive delay).
I am not even done yet and there is maybe 25% of the old code left, of which more will have to go. But the additional features are quite the reward:

• full midi mapping capability (on EVERY note)
• frequency modulation
• noise sources
• more on time modulations
• looping adsr curves
• sinusoidal modulation of note parametrs
• everything is fully programmable with a home grown graphical UI (and a backwards compatibility mode, that looks just like the settings did before)
• every note event starts a task like function that can branch out into many more, each modulating one parameter
• parameters can be taken from midi CC messages
• each note map can be either fixed frequency or at an offset from the normal midi one
• maps support disabling of modifiers like volume, stereo, pitchbend etc.
• a new (simpler) duty limiter that now reduces all note volumes by the same amount removing the weird sound when the old one was active

...and quite a bit more that I am too lazy to write down, so instead here's a preview of the advanced version of the UI (of course including a bug that I only see now that I have posted this  ):


and the mapping options:


I do know though that these features will only be used by maybe 5% of all users, so I again apologize to anybody waiting to get theirs

[TMaxElectronics]

Some more updates:

I got the VMS to the point where it is more or less done.
A few small things remain, like the live preview and some general useability improvements. I have been playing around with it a little this afternoon and it sound sooo much better that it did before (at least to me ).

Here's a little preview

[Mads Barnkob]

Some very nice updates on your USB MIDI stick!

Turning the AUX connector and moving the resistor a bit a some good fine tuning of the hardware. The resistor was JUST at the edge of my optical output, so it was not in the way, but I did perhaps stress it a bit

Seems like a serious code-overhaul, that does tend to delay delivery times a bit, I had commenters on youtube/facebook/contact form ask about where to buy this and I have just pointed them here or your website to contact you.

About your latest demonstration video, I am not quite sure what I am looking at. From your explanation here on the forum it just looked liked a single channel displaying the note peaks of the on-times. But in the youtube description you wrote:
"The different channels here have different settings:
1: Portamento, FM with a sine wave, adsr
2: only adsr
3: inverse exponential adsr"

Could you point out where on the all green oscilloscope those channels are? I guess its 1 at bottom, 2 at top and 3 is the "holes" in the bottom?

[TMaxElectronics]

The description text about channels was perhaps a bit confusing, I ment the settings of the Midi channels
The scope only has one channel connected, which is the output from the stick.

I am currently working on making some nice presets for the VMS, including a drum map. I'm not 100% happy with the sound of the drums yet though (more experimentation on a real coil is needed ), so a video will have to wait.

[TMaxElectronics]

Big update time (finally )!
The software is done and I have assembled new Midisticks.

I am still bug testing the software a little but I'm confident enough to call it V1.0 and pack the sticks tomorrow. I hope that my postal service will take the packages despite the lockdown and it being so close to christmas.
The sticks will come preloaded with a small selection of VMS maps (basically sound "fonts"), that can be expanded by me or others. I might also post a video demonstrating some of the improvements I've made.

A little "artistic" shot of the new PCBs

[tophat]

Hello!

your board looks very promising, I would love to make one, i was just wondering if i needed to buy a PIC development board to do so? Can i program the chip directly from the completed board or do i have to program it and then solder it on? Thanks so much!

[TMaxElectronics]

There are ICSP pads on the PCB. Pin 1 is next to R8
You'll need a programmer compatible with the pic32mx270f256b, I use both PicKit 3 and PicKit 4.

There is a slight design flaw with the bootloader, when programming with a pickit 3 though:
As the firmware backup mode is activated by pulling a pin on the header low, and the pickits have a default pull-down on that pin, the stick will go into firmware recovery mode, nuke the program flash and wait for code over UART when the programming operation has finished.

I'll fix that in the future, but for now you'll have to disconnect the programmer as soon as the operation has finished (within ~1sec).

[TMaxElectronics]

Finally some updates again!

I have been improving VMS a little since the last release and it now supports using scaled midi CC values as parameters, allowing for direct manipulation of VMS parameters from software like FLStudio. A single note event can now also trigger multiple tones, allowing for a much richer sounding note.
Some midisticks also found their way to some people that (other than me) actually have musical talent, so some actually good maps will come out in the not too distant future

One much more important thing however is the fact that I am thinking about releasing it as a full on product, since quite a few people have asked me if I sold them.
Everything will of course remain open source and free to replicate for those inclined to do so
I have already got myself some lead free solder paste and will be designing a little case to go around the stick.