High Voltage Forum

Tesla coils => Dual Resonant Solid State Tesla coils => Topic started by: Teravolt on May 02, 2019, 09:34:12 PM

Title: QCW music with Midi
Post by: Teravolt on May 02, 2019, 09:34:12 PM
I would like to be able to play midi notes into a QCW and I am looking for a way to convert a computer keyboard or synthasizer key board or sequencer. I am presantly designing the QCW to accept an audio input into a 300v class D amp. I am not shure how well this will work. the amp will be able to very in amplidude as well as frequency to apply to the power of a QCW. all inputs are welcome
Title: Re: QCW music with Midi
Post by: Teravolt on May 04, 2019, 11:49:56 PM
to whom may be interested, I am working un a buck converter slash class D amp and I am interested in reproducing

now I know there was much talk about this video but I want to try doing this in a CW mode or near CW mode using something like this


so I have built the traditional D-amp with the ramped waveform but why not use an audio source instead of a ramped wave. with the circuit that I am working with I should be able to input a audio input. Typically a FPGA or microprocessor this might be a easy task buy phase shifting the DRSSTC bridge but I am not very proficient with software so I am taking the low road going analog. The amp that I built has a bipolar output vs. the typical 0v-300v volt ramp for twice the voltage. one of the hertals is building silicon IE bridge that can handle the average power that it might take. instead of using transformers I am doing direct drive witch is not usably done hear because of the set up for this. to do this I am using a


as a isolated power source and I isolated driver


originally I was using a quad power supply but I have managed to condense it using these components.
they are  driving 2 of these Semikron- SKM 400GB 123D , 400A, 1200V bricks with a fall and rise time of about 130 ns.
I am writing this article to show other ways to drive FETs or IGBTs other than using transformers as well seeing if any one is interested in my work.

the picture of the schematic is my current version that I am working on and the breadboard is what it looks like at some point I am going to solder it together. the other pictures are of the current way it looks

for the filter I kind of flowed


but I used a Yellow core instead of a red core witch has a lower frequency response. The filter inductor has 2 windings wrapped in opposite directions and the pulse width signal from the half bridges are inverted to get a negative and positive ramp.

if any one is interested the tesla that I am working on is 500khz so the sword sparks can be achieved


so another current interest and that I want to try is synthesized music and my goal is to merry the beat step with the tesla


this project is on going and in depth and I am trying to see if any one has tried this or is interested
Title: Re: QCW music with Midi
Post by: Laci on May 08, 2019, 05:30:54 PM
I THINK Steve Ward did something similar with his QCW:
https://www.youtube.com/watch?v=QpKNbvonSic (https://www.youtube.com/watch?v=QpKNbvonSic)

I didn't make anything similar to this,but I'm interested,so keep up the good work!
Title: Re: QCW music with Midi
Post by: flyglas on May 08, 2019, 06:24:36 PM
the 4 QCW coils in the video are realized with phase-shifted h-bridges but the buck-converter approach is also possible (see comment on youtube). The desired note is added (modulated) on top of the standard QCW ramp.

With this you have a single straight streamer. Only within the growing time of the streamer a note is present.

Your approach with isolated dc/dc converters is very nice. I tried it with smaller 2W dc/dc converter, because the big ones are very expensive.
Edit: Wow, the MGJ6D121510DC are only 15 EUR per piece.

My attemped failed due to the low output power of the small converters.
Title: Re: QCW music with Midi
Post by: Teravolt on May 09, 2019, 06:29:36 AM
I don t care much for transformer circuits because when they don't work they are a bitch so went to developing isolated drive circuits. The infinium driver and murata dc to dc power supply were almost made for each other in that I can drive IGBT's or MOSFETs with -5 to +15 with about 2 ohms. This makes the rise and fall times fast in the 100ns times. It depends on how much capacitance is in the gate. The drivers also have sub nano second internal delay reducing your feedback to switching time thus hopping I wont have to use a phase lead circuit at the feed back input. With direct drive I can switch the MOSFETs with a TTL input and control timing, phase, dead time, or a microprocessor.

my earlier versions used quad isolated power supplies consisting of a transformer, raw dc and a 15v regulator. very easy to make for about 100$us. With that I used HFBR-2522Z fiber optics or magnetic isolator, IL710, to isolate my signal and drive a IXDD614CI or even a 30A IXDD630CI. With those FETs and IGBTs can be driven with 1-4 ohms and bipolar voltages if thought about. This can also get 100s of nano seconds or less of rise and fall times

I want to set this up to drive a bridge of IXYH100N650C3 200A 830W FETs for the DRSSTC at about 400-500KHz I made the setup I just need test and implement which will follow the D amplifier. This may take some time but I think I know what has to be done.