Re: Re: gate drive transformer of Richie Burnett's schematic
zzz_julian_zzz, Mon Aug 03 2015, 07:53AM

correct. You need to have an ocilloscope to see what's happening actually on the gates.

Re: Re: gate drive transformer of Richie Burnett's schematic
dexter, Mon Aug 03 2015, 07:59AM


not 100% required... it can be done with simple labeling of the wires

Re: Re: gate drive transformer of Richie Burnett's schematic
rajheman, Tue Aug 04 2015, 12:07PM


Thanks for reply Julian :)
I don't have oscilloscope with me right now .in this week I'm trying to buy one .then after I will check it .
One more question. As my guess I think I need supply small voltage like 12v to check MOSFET on oscilloscope right ??

Re: Re: gate drive transformer of Richie Burnett's schematic
rajheman, Tue Aug 04 2015, 12:15PM

Is anlog oscilloscope or digital storage oscilloscope is best for my circuit ??
In India digital oscilloscope are soo high in price compared to anlog. As I enquired one electronic store they quote 8000 rupees (126$ ) for 10MHz anlog oscilloscope.

Re: Re: gate drive transformer of Richie Burnett's schematic
dexter, Tue Aug 04 2015, 08:08PM

i made my first STTC without an osciloscope and it worked

all you need to do is attach labels to the GDT leads before twisting them together

Re: Re: gate drive transformer of Richie Burnett's schematic
zzz_julian_zzz, Wed Aug 05 2015, 01:18AM

@rajheman,

If you mean powering the bridge i.e. (+12 to top most drain and - to the lower most source), it's not necessary to check phasing.
You just have to check the waveform of GDT secondary(gate-source) to make sure that the "correct" MOSFETs are turning ON at the right timing. Digital or Analog will do 50-100Mhz would be fine. If you have plans on making your coil high powered/ make another one, (just make sure the Oscilloscope speed can accommodate your playing bandwidth)

@dexter,

Yup, I made 1 SSTC and 2 DRSSTCs without using an oscilloscope. But building a qcwdrsstc made me realize that I could use one, and If I could have invested earlier time, I could have saved precious transistors.


before, I even used my laptop as my oscilloscope (just to check the phasing of the logic and not to observe the actual operating frequency waveform as laptops can range up to 20khz only vs my sstc with 350khz. What I did is to lower first the clocking frequency from the TL494 / (or in UD, feeding the feedback circuit with a 18khz 555 timer square signal) luckily the bandwidth of my GDT can still play within these low frequencies. I don't know the core material/content.

Re: Re: gate drive transformer of Richie Burnett's schematic
rajheman, Wed Aug 05 2015, 09:30AM

Thanks for your valuable suggestions Julian and dexter.

I just saw video link posted by you dexter. I already labeled the wire's of GDT as u mentioned in video.

Even I checked the out put of gdt transformer with 4 led lights insted of MOSFET and they turned on and off as suggest by Julian .

As per Richie schematic left and right upper LED lights / MOSFET are on and lower left and right LEDs lights/MOSFET getting offed. Every thing is perfect.

But the problem is when I disconnected LEDs from gdt and connected the wire's to MOSFET pins as per my above mentioned schematic.there is nothing out put .no spark nothing from secondary of ssct

Re: Re: gate drive transformer of Richie Burnett's schematic
rajheman, Wed Aug 05 2015, 10:44AM

This is schematic what I did exactly as per Richie Burnett's schematic



Please check it

Re: Re: gate drive transformer of Richie Burnett's schematic
Ash Small, Wed Aug 05 2015, 12:18PM

I think you've made a mistake. It looks to me like you have both high side switches open together, and both low side switches opening together.

I think the mistake is because you've switched both the primary and secondary connections on the right hand side. You only need to switch the secondary connections, I think.

EDIT: I'm assuming switches 1 and 3 are high side and 2 and 4 are low side. 1 and 4 should be 'on' together, and 2 and 3 should be 'on' together, if I'm interpreting it correctly.

Re: Re: gate drive transformer of Richie Burnett's schematic
rajheman, Wed Aug 05 2015, 12:54PM

The windings for the two gate drive transformers are 16 turns, and each transformer has 3 winding, one primary and two secondaries. The secondaries are connected in anti phase, and the primaries of the two gate drive transformers are also connected in anti phase too

Re: Re: gate drive transformer of Richie Burnett's schematic
Ash Small, Wed Aug 05 2015, 01:21PM


I think you only need the secondaries wired in anti-phase. Wiring both primary and secondaries in anti-phase means you are back where you started.

Re: Re: gate drive transformer of Richie Burnett's schematic
rajheman, Wed Aug 05 2015, 01:46PM



Yes your right ash. Just now I have read about H bridge circuit on wikipedia


Actually I made GDT connection on the suggestions of Mr. Julian



I have confused at point 7 on Julian suggestions.
Any how thanks a lot Mr. Ash for helping me on pointing out my mistake
Thanks a lot to Mr.Julian too :)

Re: Re: gate drive transformer of Richie Burnett's schematic
rajheman, Wed Aug 05 2015, 01:55PM


You mean I just need to keep only secondary of gdt are in anti phase. But in Richie Burnett's schematic he connected left side gdt in parallel with points A and point B
But in second gdt (right side in schematic) point D and point C are crossly connected.
Plz check his schematic
Schematic 1



Schematic 2

Re: Re: gate drive transformer of Richie Burnett's schematic
Ash Small, Wed Aug 05 2015, 03:07PM

At first glance, I think he has inverted the primary only. The secondaries look to be wired the same.

Re: Re: gate drive transformer of Richie Burnett's schematic
rajheman, Thu Aug 06 2015, 08:22AM

One more last question.

sstc01.gif

In above image Richie mentioned that . adjust for 50:50 square wave out put at 10k pot .
Did he mean to adjust 10k pot to its center position ??
(I don't have oscilloscope)
Plz help this is last doubt to make my coil resonate
Thanks in advance
Regards
Rajheman

Re: Re: gate drive transformer of Richie Burnett's schematic
Ash Small, Thu Aug 06 2015, 11:51AM


I've not checked, but I assume the 10k pot adjusts the duty cycle. 50% is unlikely to be the mid point of the pot.

I can't think offhand of an accurate alternative to a 'scope. Maybe others who have built this without a 'scope can help here?

(EDIT: Maybe it's possible to charge/discharge a capacitor through a resistor, and measure where the average voltage remains constant, or some similar method?)