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Old 10-09-2017, 02:37 AM
serendipitor serendipitor is offline
Join Date: May 2014
Location: Western Washington
Posts: 41
Originally Posted by Netica View Post
What do you think about the load on the transistors/MOSFET'S under these pretty much short circuit conditions?
That depends on the switching frequency and the permeability of the core material. I would guess that they were using something in the range of 50kHz-100kHz. If the core has high permeability, that allows even a few turns of coil plenty of inductance. The circuit probably does have some large peak currents in the primary, possibly 50A, but just for a very brief periods, say 100uS or so.

This kind of circuitry is common now in DC to AC inverters, where a low voltage like 12VDC at 100A (or more) is switch converted to 180VDC, then PWM to 120VAC.

Another comment: In the Mark McKay presentation on this same circuit, he commented that the central cylinder of the transformer core had been machined out and replaced with an iron core. The present image from Al's talk does not show this at all, and could be another one of these murky areas where deliberate changes were made by Hackenberger (or someone) to hide or obfuscate actual functioning circuitry. I would say that at the switching frequency implied by the windings, there would be extreme heating induced in an iron core, and such would not be workable.

Last edited by serendipitor; 10-09-2017 at 03:29 PM.
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