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Re: gate drive transformer of Richie Burnett's schematic

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rajheman

Fri Jul 31 2015, 05:37PM

Registered Member #54872 Joined: Fri Apr 17 2015, 06:33AM
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Posts: 25

Is this attached schematic by me is right or wrong ??
About gate drive transformer winding and its connection to MOSFET pins for Richie Burnett's schematic

Plz help
Thanks
Regards
Rajheman

zzz_julian_zzz

Mon Aug 03 2015, 07:53AM

Registered Member #3964 Joined: Thu Jun 23 2011, 03:23AM
Location: Valenzuela City
Posts: 332

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

dexter

Mon Aug 03 2015, 07:59AM

Registered Member #42796 Joined: Mon Jan 13 2014, 06:34PM
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zzz_julian_zzz wrote ...

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

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

rajheman

Tue Aug 04 2015, 12:07PM

Registered Member #54872 Joined: Fri Apr 17 2015, 06:33AM
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Posts: 25

zzz_julian_zzz wrote ...

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

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 ??

rajheman

Tue Aug 04 2015, 12:15PM

Registered Member #54872 Joined: Fri Apr 17 2015, 06:33AM
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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.

dexter

Tue Aug 04 2015, 08:08PM

Registered Member #42796 Joined: Mon Jan 13 2014, 06:34PM
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Posts: 195

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

zzz_julian_zzz

Wed Aug 05 2015, 01:18AM

Registered Member #3964 Joined: Thu Jun 23 2011, 03:23AM
Location: Valenzuela City
Posts: 332

@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.

rajheman

Wed Aug 05 2015, 09:30AM

Registered Member #54872 Joined: Fri Apr 17 2015, 06:33AM
Location:
Posts: 25

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

rajheman

Wed Aug 05 2015, 10:44AM

Registered Member #54872 Joined: Fri Apr 17 2015, 06:33AM
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Posts: 25

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

Please check it

Ash Small

Wed Aug 05 2015, 12:18PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

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.

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