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 Post subject: Offline Flyback DC-DC converter using NE555, Works in LTSpic
PostPosted: 28 Jul 2017, 05:23 

Joined: 28 Jul 2017, 05:21
Posts: 1
I'm currently a novice and am learning EE. I've been experimenting with low voltage DC-DC converters. Now I want to build an offline DC-DC converter that operates directly from AC mains.

The schematic works very well in simulation, but being this converter draws its power directly from AC mains, I'd like some input from experienced users/professionals before I build this thing and test it in a real world scenario.

This NE555 circuit is only a learning tool. The objective was to take on a project way beyond the scope of my knowledge and I decided to build a SMPS using basic oscillators and designing all of the auxiliary circuitry around them.

Here is the datesheet of ne555n

I'm aware of the existence of and have many different SMPS control ICs.


I took the entire circuit apart and rearranged it a bit. I realized in order for PFC to really work the transformer has to be wound for the max voltage, so I'm operating the boost converter from a pre-regulator then once the boosted output hits 360VDC it starts up the flyback circuit. Once the flyback's regulated output reaches 14.8V it shuts the pre regulator off. All occurring within a half a second or so.

Will the pre-regulator blow up? I know I'll survive up to 170VDC I've tried these (get very hot after a few minutes, but will power an NE555 and a few transistors), but at 340VDC? I know the jump from 340 to 360 won't take more than 60ms, could be safe, but What do you guys think?

Here's are the latest revisions The output results are with PFC output @ 360VDC carrying a 129Ω load (>1KW)

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