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Universal SSTC Control Module with all the bells and whistles

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Ken M.

Sat Dec 11 2010, 06:10PM

Registered Member #618 Joined: Sat Mar 31 2007, 04:15AM
Location: Us-Great Lakes
Posts: 628

For a while now I've wanted to have the ability to actually see the values and readings from a Tesla coil that I was running, you know the basics, Fres, the frequency of my interruptor, the duty cycle of the interruptor, Vin Secondary Voltage. Now with DRSSTC becoming more the "in" coil have you need to monitor amperage and set an OCD limit.

Now some of you may think why do this when a good ole rusty 555 some pots and caps work just fine, the thing is, is that with a 555 timer and said parts your limited to the frequency range of the RC circuit, sure I could also use a TL494, but then I still need a variety of caps, and pots to cover a wide range of frequencys at least for a SSTC, wheres if you use a microcontroller, you could just press a button to change ranges, and use a single pot on an ADC pin to allow fluid range changes, the only major issue with using a uC is that it's very suceptable to EMI and RFI.

So I present my Universal SSTC Control Module, running a stm8s105C6 (on discovery board ATM), and 128x66 LCD From spark fun.

ATM it has 5 ranges (1-10.11Hz, 3.90-39.09Hz,38.16-382.6Hz, 391.7-3909.5Hz, and 4148.6-41120Hz (according to the display)) which has a 1% readout accuracy through the entire range and an adjustable duty cycle from 1-99% ontime.

A little excel Graphage to show the values I measured from the Oscope (with digital readout of frequency) and the recorded value on the LCD Display screen.

and the second accompanying graph with the displayed values inverted since its kind of hard to tell with them being 1% accurate and having such a large scale.

So far I still need to build the actual board for the module and the board for teh driver since I'll need 2 microcontrollers 1 in the control module and one on the driver board to reduce noise in either the measurement lines, and on the TX nad RX lines, draw a schematic for the system, decide wheteher or not I'm going to use I2C or upgrade to a chip that has 2 UART lines to be able to talk to the driver chip, and the making enclosures that will somewhat Sheild the micros from the RFI and EMF, produced by a TC.

radhoo

Sat Dec 11 2010, 07:03PM

Registered Member #1938 Joined: Sun Jan 25 2009, 12:44PM
Location: Romania
Posts: 701

I love the idea, actually I also wondered why there are so few tesla coil builders the use uC.

The code allows you to generate a wide range of signals, and via a simple interface you can customize everything during runtine.

Would be great if you'd post the uC code as well. Looking forward to your next results.

Ken M.

Sun Dec 12 2010, 02:49AM

Registered Member #618 Joined: Sat Mar 31 2007, 04:15AM
Location: Us-Great Lakes
Posts: 628

Well I've been a nerd all day and have mostly been revising the code and adding little things here there that I felt needed, now I kind of feel it has everything needed and takes the entire display area to show everything, and also neccessatated the need for an upgraded power source for the display, which now showcases:

Primary Current (measured from a CT on the Bridge Board, and read by a micro on the Driver board then transmitted to the module.
OCD which will be set via a pot on the driver board and transmitted to the controller.
What mode the controller is in be it single shot or Pulsed.
What the frequency of the pulse is and the duty cycle with graphic square.
Fresonant which will be measured by a CT on the secondary base and limited to 5V and will be read by the micro on the Driver board as well then sent to the controler.
The secondarys amperage yet another CT and reading process, as well as a Sec voltage reading (mostly calculations).
A battery voltage indicator for the controller since I'll probably go with a LiPO pack because they are very dense nad I have a nice RC lipo charger that can charge upto 12 cells (not like I'm going to use that many).
Finally a Primary voltage reading.

I'll post the code once its mostly commented then add revisions as I actually implement some of the 2 micro parts like Primary and secondary Current and voltage, but for now a screen shot let me know if you think thats too much stuff.

Ken M.

Mon Dec 20 2010, 07:16AM

Registered Member #618 Joined: Sat Mar 31 2007, 04:15AM
Location: Us-Great Lakes
Posts: 628

This isn't much of an update, but here's the code still needs a lot of work and is only 50% done and is missing a lot of commenting, plus I have a 2 or 3 glitches that I'm trying to fix on the display side, other than that I've got a case ordered made out of white oak veneer that's laser engraved, plus I got the encoders and pot to adjust the settings, hopefully tomorrow or Tuesday I should have a video of it just to kind of demonstrate whats going on.

]cmcode.zip[/file]

kerver

Fri Dec 24 2010, 08:34AM

Registered Member #522 Joined: Thu Feb 15 2007, 01:04AM
Location: The Netherlands
Posts: 33

Im wonder how this in circuit component value's is and looks like:-)

(The secondarys amperage yet another CT and reading process, as well as a Sec voltage reading (mostly calculations).

Ken M.

Sat Dec 25 2010, 03:12AM

Registered Member #618 Joined: Sat Mar 31 2007, 04:15AM
Location: Us-Great Lakes
Posts: 628

So Far I have most of the calculations done for measurements and in most cases down to a 1% tolerance, for example if I measure a frequency which is between 1Hz and 50kHz the values on screen are with in 1% of the actual measured value on an oscilloscope, and in most cases its actually closer to .5% tolerances with a few exceptions being around 1% tolerance due to using random numbers during the calculation process for that range.

The same for any of the voltage measurements for the battery, which I'm hoping will come out to at least 10% tolerances.

Ken M.

Wed Jan 05 2011, 06:06PM

Registered Member #618 Joined: Sat Mar 31 2007, 04:15AM
Location: Us-Great Lakes
Posts: 628

Isn't much of an update but I recently received my controls front, left and right enclosure panels the I had laser etched from ponoko.com, these panels are made from a single piece of .25" White oak veneer that was 7x7".

Now all I need to do Is figure out what I'm going to do about the front, back, and bottom of the enclosure and how to shield the entire thing.

Also because I promised I'd upload the source code, and Haven't yet here it is in its current rendition, I may be adding a few extra features to fully utilize the two rotary encoders with built in buttons, and the potentiometer, as well as to de-clutter the screen alittle and offer a selection screen at the beginning of power power up after the splash screen.

]cmcode.zip[/file]

genious 7

Mon Jan 17 2011, 01:20PM

Registered Member #2887 Joined: Sat May 29 2010, 11:10PM
Location: Panama City, Panama
Posts: 107

This looks promising. Just as a question, how are you planning to shield the uC against the electromagnetic noise from te Tesla Coil. Is the Uc having a dedicated power supply or something, since if the power variates for a fraction of a second, the uC will reset.

Ken M.

Mon Jan 17 2011, 01:55PM

Registered Member #618 Joined: Sat Mar 31 2007, 04:15AM
Location: Us-Great Lakes
Posts: 628

The entire unit will be ran with a single Lipo battery the screen will have a boost converter to power it, and as far as sending the data to and from the coil as well as the pulses I'll be using fiber optics, via a toslink setup.

I should upload a schematic of this whole thing sooner rather then later but I don't have everything setup yet, and most of the design is still just in my head.

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