3rd world problems
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Doge123
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Registered Member #61418
Joined: Mon Jan 09 2017, 03:52PM
Location:
Posts: 1
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Hi guys! I am from a country called Nepal. I have always wanted to build a singing Tesla coil and I have recently started collecting parts. I based my design around the OneTeslaTS DRSSTC whose schematics and tutorials were easily available online. It is quite hard to source parts in this part of the world which is ironic since China is our next door neighbors. Anyways, some kind gentleman online sent me some gate driver ICs UCC37321 for free. Thanks again random stranger. Now, I have run into a problem. Only IGBTs available in our country is bootleg FGA25N120 (it is widely used in induction cookers and heaters) which has quite slow turn off delay time of 170ns at 25C. I don't know if I can get anything usable out of it. What is the general rule for IGBTS. How fast do they need to be for a given frequency?
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Conundrum
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Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059
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Can you compensate for this by using resistors? IIRC IGBTs are a hybrid of a BJT and a MOSFET (Insulated Gate) so they in common with MOSFETs have a significant gate capacitance.
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Bjørn
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Registered Member #27
Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058
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If we make a guess and say it should be fully on for about 90% of the time. frequency = 1 / ((turn on time + turn off time) * 10) = 294 kHz (If turn on is as slow as turn off)
How well it will work for your application depends on how good your heatsinking is and what you would consider to be a good result.
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