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Teh Multipurpose Inverter

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uzzors2k

Sat Dec 08 2007, 10:05PM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

I've had this for a while but just recently I got a potentiometer for frequency control, making it complete. It's an all-around inverter, which can power flyback transformers, induction heaters and even low frequency Tesla coils if you dare. With duty cycle and frequency control + primary over-current shutdown it's quite versatile. Running loads offline at "high" frequencies has never been easier.

1197151304 95 FT0 Et Multipurpose Inverter

Tonic

Sat Dec 08 2007, 10:10PM

Registered Member #528 Joined: Fri Feb 16 2007, 10:32PM
Location: Warsaw, Poland
Posts: 166

Funny thing, also I'm working on versatility of NE555 driver. Actually it has duty cycle regulation and now I'm messing with frequency regulation. Damn, you were faster

But tell me, what is thing in left side of scheme?

EDIT:

Why didn't you replace BD's with 2N2222 and his complement?

Marko

Sat Dec 08 2007, 10:43PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Aw, more ghetto than mod I've just done on an ATX supply..

I hope nothing will short out in that box.

I have similar thing here - OCD isn't that elite, but works.

I always prefer controllers with totem-pole outputs for driving isolated gate devices, they make things much easier. TL494 is better for bipolar transistors from other side.

uzzors2k

Sun Dec 09 2007, 10:56AM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

The BD's work good enough for the frequency range of the TL494, max they're ever experience is 250 kHz.

I didn't like the TL494 either, it took me a year to find an output configuration which would allow for GDTs to be driven with PWM - but they're cheap and easy to find so I've just stuck with them. And I've gotten used to the pin layout. Your mini inverter is pretty leet Marko, is the half-bridge on the same board too?

My projects seem to become a mess of circuit boards stuck in a box, just see the bench smps I made. (Other project thread.)

jpsmith123

Sun Apr 06 2008, 03:11AM

Registered Member #1321 Joined: Sat Feb 16 2008, 03:22AM
Location:
Posts: 843

Hello Uzzors,

I'm curious how your "Multipurpose Inverter" has been working out. For example, I'm wondering what kinds of things have you driven with it, and how much power have you put through it? Also, how reliable is it so far...have you exploded any Mosfets yet?

If it works well enough, I think something like that might have some commercial potential as a kit for hobbyists or something.

Regards,
jpsmith123

Arcstarter

Sun Apr 06 2008, 04:27AM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

Uzzors,you show me that thing run a tesla coil and i will show you a redneck that does NOT like nascar and beer.

uzzors2k

Sun Apr 06 2008, 09:19AM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

Mosfets pop all the time, from overheating for the most part. I've only used it to power flybacks and an induction heater, at unknown power levels. The IRFP450's can take 14A, so as long as the reactive current is kept under control there is potential for say, 1.5kW of output power.

Arcstarter wrote ...

Uzzors,you show me that thing run a tesla coil and i will show you a redneck that does NOT like nascar and beer.

If I had secondary with a resonant frequency under 250kHz I would gladly make you prove the impossible. Will this 555 based offline SSTC be enough? I mean, if a 555 can do it so can a TL494. Hang on, here's the circuit I meant to show.

Of course it has been replaced since then, but it worked at one time.

Dr. Dark Current

Sun Apr 06 2008, 10:47AM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Uzzors wrote ...

Mosfets pop all the time, from overheating for the most part. I've only used it to power flybacks and an induction heater, at unknown power levels. The IRFP450's can take 14A, so as long as the reactive current is kept under control there is potential for say, 1.5kW of output power.

Wait, the IRFP450 has 400mOhm resistance, with 14 amps that is 80 watts!

The output power you stated would be only for voltage sources.
For current limiting sources (such as flyback driver), the maximum achievable output power with the same bridge current is exactly 1500/4= 375 Watts of real power.
This is assuming that 1) the inverter is hard switching and 2) there is only inductive reactance limiting output current (which is the case with flybacks and their leakage inductance).

Cheers

J.M.

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