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I'd like to have a constant PWM signals, much like this:enter image description here

Wherein the blue trace have centered it's hi at the 0 of the fully rectified AC & the red have centered it's lo on the 0 of the fully rectified AC, as well.

Note, also, that the blue & red traces aren't complementing waveforms that are 0 sum, as they have noticeable gaps. Being able to do this dichotomously is required, rather than inverting at a last step.

For robustness, I allow for distortions in the original AC (slight shifts in phase, say), so PWMs that started on the initially correct trigger won't be enough, as it won't follow the rectified AC properly.

What I'm looking for is a cheap, yet robust mechanism, where the PWM generator keeps re-aligning itself to the 0 point; one that keeps falling into it.

So I've been looking at crystals, oscillators, resonators, but I'm quite ill-informed with using them.

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  • \$\begingroup\$ Define all sources and loads. It looks like a full wave rectified sine with two complementary pulses with a large dead-band and define application \$\endgroup\$
    – Tony Stewart EE75
    Jun 25, 2022 at 22:30
  • \$\begingroup\$ This is to time my design of a Boost Converter. The PWMs are controlling the transistors. The reason for the dead band is the red trace's transistor trying to catch the voltage surge at the edges of the other transistor \$\endgroup\$
    – Tempus Nomen
    Jun 25, 2022 at 22:35
  • \$\begingroup\$ I basically want a Boost Converter logic without ICs. \$\endgroup\$
    – Tempus Nomen
    Jun 25, 2022 at 22:37
  • \$\begingroup\$ Come to think of it, the timing might be off. Well, once this get's fixed, the timing's minor. \$\endgroup\$
    – Tempus Nomen
    Jun 25, 2022 at 22:42
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    \$\begingroup\$ Unless you define parameters for In/Out and load with a configuration , the question is meaningless \$\endgroup\$
    – Tony Stewart EE75
    Jun 26, 2022 at 2:37

1 Answer 1

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I basically want a Boost Converter logic without ICs.

No problem: look at the architecture of a boost converter controller, then implement all the blocks using discrete transistor circuits. Just like any analog IC designer would do...

Of course you'll have to learn about all those building blocks first, and you may wish to start with an op-amp based implementation before you go down to transistor level. The op-amps will teach you a lot that you'd need to know before going down a level.

What I'm looking for is a cheap, yet robust mechanism, where the PWM generator keeps re-aligning itself to the 0 point; one that keeps falling into it.

Why do you believe that it's some sort of a problem that needs to be solved? There are lots of "on the cheap" boost converter designs out there.

You really need to get old National Semiconductor databooks, Linear Technology app notes, etc. - lots of various boost converter designs are there that re-purpose various chips to do it. Probably someone made one using a 555 timer too. And a 555 is a fairly easy thing to duplicate.

If I recall correctly, there's even a way to co-opt a TL431 to do that. And reproducing TL431 from discrete transistors is simple compared to reproducing all the block of a modern boost converter controller IC.

The simplest of boost converters would use a 1- or 2-transistor oscillator and a 1-2 transistor regulator that stops the oscillation when the output voltage is high enough.

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