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Messages - profdc9

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Dual Resonant Solid State Tesla coils (DRSSTC) / Re: DRSSTC PCB pack release includes UD2.9 skip pulse gerbers

« on: March 15, 2021, 08:35:37 PM »

Quote from: Mads Barnkob on March 13, 2021, 02:04:10 PM

Hi Dan

I build the interrupter with normal, burst, audio and USB MIDI options. Left out the MIDI for now as I got so many others.

The input voltage range of the LM339 is Vcc -2V at worst, so when I want to run the whole board at 5V, that leaves me with only 0-3V audio input range, what is it currently designed to take with the 9-12V supply voltage?

Yes, I designed it to take a 9-12 V supply. But I think it should still work at 5 V. The threshold for audio input to trigger a pulse is the voltage drop of a Schottky diode, about 0.2 V, high enough above the rail to work reliably. Everything else is triggered to a threshold voltage created by the voltage divider of R8/R9. If you are having problems, decrease R8 from 10k to perhaps 6.8k so it is well below the LM339 common-mode limit.

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: Through-hole layout of UD2.7C universal driver

« on: March 03, 2021, 04:22:01 AM »

When laying out the board, it was impressed upon me (by G. Guangyan the creator of the ud27c SMT board) that I should have very wide traces from the IRF540/IRF9540 source leads and the 24 volt bus capacitors. This is because in order to switch the MOSFETs rapidly the edge of the gate drive signal will likely have to be 100 ns or less in duration which requires a large peak current especially for big IGBT bricks. On this board and the ud29 version of the board I had a GND/+24 V fill around these to ensure that there would be a very low resistance/inductance path from the bus capacitors to the MOSFET sources. There are also ceramics very close to the MOSFETs to provide extra low impedance charge which seems to be there in the new layout. This was a major constraint on the layout, but I think you should do this as well. It is also important to keep signal lines as short as possible, especially for paths like the positive feedback (hysteresis) in the high speed comparator. Otherwise it could either act too slowly or it could oscillate. I think it is more important for a layout to have there properties than it is to be a single layer because it is so easy nowadays to have boards manufactured. Long curvy paths to keep the traces from crossing on a single layer are likely not as good as short wires that cross each other on opposite layers at right angles. Also it is crucial that decoupling caps have definitely short, local traces to the chips that they are supposed to decouple the supplies for. Since it looks like most of the top layer is ground, that is likely not a problem.

Also, if you do intend the board to be used with links on a one-sided board, you should change the vias to have a wider copper gap around them because there will be no solder mask to prevent bridges between the link pads and the surrounding copper fill.

The layout is definitely in some ways better than mine, but I think it has to ensure that the sharpest edge can be delivered through the gate drive possible.

Dan

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: Through-hole layout of UD2.7C universal driver

« on: March 02, 2021, 05:04:44 PM »

You might want to consider trying the ud29 design as that includes skip pulse functionality with very few changes from ud27.

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: Through-hole layout of UD2.7C universal driver

« on: March 01, 2021, 05:12:05 PM »

The optical receivers are in the cache library. If you recover the project it will find them, but probably they should be in their own library. But I think the library symbols you are looking for are in the project cache library.

Dan

Quote from: Max on March 01, 2021, 04:56:33 PM

It seems as if the standard parts like the logic chips migrate without issues. but the optical receivers f.ex. don't. Hence I suspected that you didn't add those symbols and footprints to a project library, but to your system library which is not part of the git repository - and thus not available to me.
The optical receivers are the only thing I can remember right now. If this is not enough to track down the origin of the issue, i can make a complete list.

Kind regards,
Max

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: Through-hole layout of UD2.7C universal driver

« on: March 01, 2021, 04:41:08 PM »

I just loaded the file into kicad 5.1.8 and the library symbols were migrated over it seems without any problem and the design rule check worked with only minor issues like courtyard overlapping (which just means the components are a little close in places).

Could you let me know which library symbols or footprints are missing?

Quote from: Max on March 01, 2021, 12:14:54 PM

Hi profdc9,

I wanted to play around with the layout, however, I can't open the project in the current version of KiCad (5.1.9). It seems like part libraries are missing. I don't know how libraries worked in older KiCad versions but in the current ones you should definitely add project specific parts to a separate, project specific library.
Anyways, before spending hours with sourcing the components and footprints you used, could you migrate the project to the current KiCad version and inlcude a library with all the symbols and footprints?
I reported this as an issue on GitHub, too, but didn't know whether you have your notifications turned on.

Thank you!
Max

General Chat / Horizontal Jacob's latter in power lines

« on: February 15, 2021, 09:01:30 PM »

In Louisiana, USA, the winter storms have caused blackouts and other electrical problems. Watch the horizontal Jacob's ladder between the phases of the power lines:

https://twitter.com/ABC/status/1361393756067487744

Electronic Circuits / Re: Interesting self-oscillating half-bridge article

« on: January 01, 2021, 08:19:33 PM »

For a full-bridge version of this, does one do the obvious thing and just feed the two halves of the bridge with opposite phases of the gate transformer? And is the current limited in the circuit mostly by shifting the oscillation frequency to be further above resonance, as it does not appear that a series inductor with the load can be used to limit the current because the resonance frequency and therefore oscillation frequency will shift down accordingly?

Quote from: davekni on December 27, 2020, 08:53:32 PM

First time I've seen that circuit implemented with IGBTs. I've used it in both half and full bridges with BJTs. For BJTs, that simple circuit is convenient. CT ratio defines the forced-beta. With a 10:1 CT, base current is always 10% of collector current. I've heard that some CFLs use the BJT version.

Electronic Circuits / Interesting self-oscillating half-bridge article

« on: December 27, 2020, 05:45:41 PM »

I found this interesting self-oscillating half-bridge article

Bal, G., Oncu, S., & Ozbas, E. (2013). Self-Oscillated Induction Heater for Absorption Cooler. Elektronika Ir Elektrotechnika, 19(10), 45-48. https://doi.org/10.5755/j01.eee.19.10.5894

https://eejournal.ktu.lt/index.php/elt/article/view/5894

It uses a gate drive transformer in series with the load to drive the gates of the half bridge, with the two upper and lower gates being driven in opposite phases. An inductor Lss (see figure 1) is included so that the oscillation frequency is somewhat higher than the resonance frequency, achieving ZVS.

It looks like a particularly simple setup for a self-oscillating half bridge. If anyone has experience with this perhaps they could comment?

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: Have you ever tripped a breaker during normal operation ?

« on: December 02, 2020, 06:20:35 PM »

I have a full bridge of FGH60N60 running on doubled 120 VAC (330V bus voltage). I use pulse skip mode so that the peak current is only 120 A and the pulses are somewhat longer than ordinary interrupter mode which ends the pulse when the overcurrent limit is exceeded.

Since this mode stays pretty close to the SOA for the IGBTs, and the duty cycle is pretty low, I have not had a problem with blowing the IGBTs. However, I can easily drive the full bridge hard enough to trigger a 20A breaker. In fact, I usually do just that when I play Bach's Toccata and Fugue. However, it has never caused a problem because there is undervoltage protection on the driver board so it shuts off and does not allow shoot-through of the IGBTs as the bridge is powering down. All that is required is to reset the breaker, allow the overload trip to cool, and it's back in business. At least so far.

So no problems here.

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: ud2.7 list of components so other's dont have to struggle like i did

« on: November 18, 2020, 04:32:37 PM »

I have a version called ud29 which also provides pulse skip for basically nothing additional (one transistor)

https://github.com/profdc9/DRSSTC-PCB-Pack/tree/master/ud29

Quote from: octopus1 on November 18, 2020, 02:07:15 PM

welp, i would have much rather done a thru hole version. Thanks if this one doesn't work i will just wait a bit till i can restock the hobby fund and try.

regards,

Electronic Circuits / Re: Nixie clock build

« on: November 18, 2020, 12:24:24 AM »

If you're curious, you could check out this Nixie clock project I did

https://github.com/profdc9/NixieClock

It uses an Arduino and no obsolete electronics (except for the Nixie tubes of course) and uses the 555 timer boost converter to avoid proprietary ICs. It is based on shift registers and is therefore expandable.

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: ud2.7 list of components so other's dont have to struggle like i did

« on: November 18, 2020, 12:18:57 AM »

I have a BOM in my UD2.7 build

https://github.com/profdc9/DRSSTC-PCB-Pack/blob/master/ud27c%20thru%20hole/ud27c%20BOM.pdf

which is the overall project

https://github.com/profdc9/DRSSTC-PCB-Pack/

which you can download a ZIP file of.

Electronic Circuits / Re: Complete 300 watt audio amplifier project

« on: November 15, 2020, 03:11:16 AM »

Generally they will drive frequencies up to about 100 kHz into 8 ohms with increased distortion. The amplifier uses the high open loop gain to minimize distortion and this is reduced at higher frequencies. Capacitive loads can definitely destabilize the feedback, and many ultrasonic devices are capacitive. Some combination of resistance/inductance network is usually used to limit the current through capacitive loads. Inductive loads are less of a problem but of course high inductance means that the effective load impedance is increased at high frequencies (and current is less).

With the ON Semi transistors with 30 MHz fT and good SOA (MJL1302/MJL3281), you can drive hundreds of watts using 4 NPN/PNP pairs so 100 watts should be no problem.

Electronic Circuits / Complete 300 watt audio amplifier project

« on: November 13, 2020, 01:17:41 PM »

Hello,

I have designed and made available schematics, gerbers, heatsink drill patterns, and construction documentation for a 300 watt class AB BJT-based audio amplifier. It is intended to be a complete design for educational study that also has flexible part substitution. It can be found at the github

http://www.github.com/profdc9/PowerAmpAudio

It is a high quality amplifier you can build yourself, save some money over an expensive commercial amp, and learn how to do it in the process. It includes the amplifier, a power conditioning PCB, a soft start PCB to limit current inrush, and an balanced (XLR) to unbalanced input.

Check out the github, there's a lot of stuff there.

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: UD2.9 skip pulse assembled

« on: October 19, 2020, 03:39:49 AM »

Could you post a PDF of your complete schematic? I'm having a problem reading your .sch file.

Dan

Quote from: Maju on October 18, 2020, 11:14:53 PM

Those Inductor shells are also on aliexpress, that's nice to know about that. Thanks!

The changes I've made are only between LT1016 and "AND" gates (attachement jpg).

I had a huge problems with phase lead adjust with only an inductor on my big bricks inverter. If I adjust phase lead very early (for optimal switching on), I have a problems with turning off to early and then strange things happen. That's why I have this idea and it's not only my idea. In my coutry almost everybody use Hammertons Predikter because of that issue But I love SKP feature, UD is easier, cheaper, more complete and more ... universal?

Your design is so great and it would be a pity not to use it to make this improvement.

Please analyze the changes and say what you think about it. If it's to hard, that's ok. Then the only solution will be a new board from the scratch.

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: UD2.9 skip pulse assembled

« on: October 18, 2020, 09:54:48 PM »

I will take a look at the schematic. The PCB is already pretty full. You can wind your own coil using these forms you can buy:

https://www.ebay.com/itm/20-Pcs-Inductor-Shell-Skeleton-Empty-Ferrite-Core-No-Inductor-Coil-25-100MHZ/172915617600

You just wind your own magnet wire (I used 30 AWG) and solder it to the pins. Then there is a ferrite slug in there you can adjust the inductance with. Using this, you can make inductors with different tuning ranges.

Quote from: Maju on October 18, 2020, 03:28:04 PM

you don't need to use adjustable coils (they are sensifive and hard to find in stores - I have to remove them from old xD radios), a simple coil for a few cents is enough

Computers, Microcontrollers, Programmable Logic, Interfaces and Displays / Re: Polyphonic Interrupter with STM32F103C8T6 (Bluepill)

« on: October 07, 2020, 04:43:20 AM »

I used the USBComposite library for my vector network analyzer ( http://www.github.com/profdc9/VNA ) and Roger's stm32duino core. You can use it in place of the built-in USB serial if you compile without it. For example:

void usb_init_serial() { if (usb_initialized) USBComposite.end(); usb_initialized = 1; usb_reenumerate(); USBComposite.clear(); USBComposite.setProductId(VENDOR_ID); USBComposite.setProductId(SERIAL_CDC_PRODUCT_ID); CompositeSerial.registerComponent(); console_setMainSerial(&CompositeSerial); USBComposite.begin(); //while (!USBComposite.isReady()); } bool usb_init_mass_storage() { DWORD sectors; flash_mount_fs_card(); if (!flash_fs_mounted) return false; if (disk_ioctl(0, GET_SECTOR_COUNT, &sectors) != RES_OK) return false; if (usb_initialized) USBComposite.end(); usb_initialized = 1; usb_reenumerate(); USBComposite.clear(); USBComposite.setProductId(VENDOR_ID); USBComposite.setProductId(MASS_STORAGE_PRODUCT_ID); MassStorage.setDriveData(0, sectors, sd_read, sd_write); MassStorage.registerComponent(); console_setMainSerial(NULL); USBComposite.begin(); while (!USBComposite.isReady()); return true; }

I have not tried the MIDI support, however, but the USBSerial and USBMassStorage works for me.

Quote from: Zipdox on October 06, 2020, 12:41:33 AM

I can use my laptop but I's slightly inconvenient.
Regarding using USB, I looked into it but I couldn't find any USB libraries that are compatible with the STM32Duino core. USBComposite requires a different core that I was unable to get working. I might try again when I have more time on my hands. I'm kinda busy this week.

Transformer (Ferrite Core) / Re: One NOS ac flyback is nice. Finding its identical twin 3 months later is awesome

« on: September 26, 2020, 10:48:41 PM »

I have two similar flybacks like that. Be careful! They arc between windings quite readily. I patched mine up with some epoxy, but be warned. I think the insulation strength decreases over time.

Laboratories, Equipment and Tools / Re: Moving to a new lab!

« on: August 14, 2020, 12:55:12 AM »

You are on your way to having the technical sophistication of Gordon Freeman.

Quote from: Mads Barnkob on August 12, 2020, 10:30:54 PM

The old rotten and leaking workshop wall and door appeared to be installed on top of an even older rotted wall. It was time to do it properly, I broke everything down and built a new wall with fiber cement, insulation and some proper wood panels on the inside.

/>

Transformer (Ferrite Core) / Re: Air Gap: why and how much?

« on: August 13, 2020, 10:59:27 PM »

The air gap increases the reluctance of the magnetic circuit that contains the primary and secondary windings.

https://en.wikipedia.org/wiki/Magnetic_reluctance

Some increase in reluctance can be beneficial as the amount of flux in the circuit will be reduced given a certain of ampere-turns of your winding. The gap which is useful for switching power supplies like flyback transformers that transfer the energy stored in the gap. It also increases the amount of current tolerated before the transformer saturates.

For other kinds of switching supplies that use direct coupling of the primary and secondary windings, an excessive large gap can create too much leakage inductance that reduces the current and can create large voltage spikes on the switches (MOSFETs or IGBTs).

You can use a piece of tape to introduce a small gap in a U/I core transformer. I have example formulas on calculating the gap size in this document:

https://drive.google.com/file/d/0BwFicJLV0O4jYlQ0ejJ6NE9XVE0/view

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Show Posts

Messages - profdc9

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: DRSSTC PCB pack release includes UD2.9 skip pulse gerbers

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: Through-hole layout of UD2.7C universal driver

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: Through-hole layout of UD2.7C universal driver

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: Through-hole layout of UD2.7C universal driver

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: Through-hole layout of UD2.7C universal driver

General Chat / Horizontal Jacob's latter in power lines

Electronic Circuits / Re: Interesting self-oscillating half-bridge article

Electronic Circuits / Interesting self-oscillating half-bridge article

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: Have you ever tripped a breaker during normal operation ?

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: ud2.7 list of components so other's dont have to struggle like i did

Electronic Circuits / Re: Nixie clock build

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: ud2.7 list of components so other's dont have to struggle like i did

Electronic Circuits / Re: Complete 300 watt audio amplifier project

Electronic Circuits / Complete 300 watt audio amplifier project

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: UD2.9 skip pulse assembled

Dual Resonant Solid State Tesla coils (DRSSTC) / Re: UD2.9 skip pulse assembled

Computers, Microcontrollers, Programmable Logic, Interfaces and Displays / Re: Polyphonic Interrupter with STM32F103C8T6 (Bluepill)

Transformer (Ferrite Core) / Re: One NOS ac flyback is nice. Finding its identical twin 3 months later is awesome

Laboratories, Equipment and Tools / Re: Moving to a new lab!

Transformer (Ferrite Core) / Re: Air Gap: why and how much?

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