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Regenerating lower AC sine wave

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New Member
Is there ever a need to fully regenerate a lower AC sine? And if so how?

Using a trigger and a triac, zero crossing switching or not, to chop the AC up and "reduce" the voltage works for light dimmers and motor controllers. But is there a way to emulate a variac using chips? To get around the problems with phase (or burst) control?

From a DC circuit's perspective (not a motor or lamp) is having voltage only half the time the same as having constant swing that only goes half as far?

When I make a DC circuit to run off mains it gets a full bridge and filter cap(s) at least. Maybe a regulator. Either way Vdc will be lower if I reduce the Vac coming out of the transformer. (unless the AC was so over-spec that the regulator can still get enough V to regulate.)

Imagine something with 3 types. A lighted digital hairdryer. So chopped the heater core would run cooler, the fan would run with less RPMs, and the light would be dimmer. But would the auto-cutoff timer run longer, being supplied with the same voltage but just chopped for duration? Or if the temp was sampled from a thermocouple and a uC, would the heater core actually run at the same temperature as non-chopped?

Not that I want to see if televisions smoke when you drive them with 55Vac or anything. I just want to understand. I should probably investigate "true sine" country power adapters.

Any suggested reading? Thanks.
generating AC

If i remmeber correctly, DC-AC inverters work by feeding a low voltage, high current 60HZ sqaure or triangle wave into a big transformer, whose magnetic properties have the tendency to smooth the signal into a sine. Of course I could be completely wrong.

The real way to make AC is to get yourself a shovel, a giant turbine and then relocate to near a waterfall.


Active Member
I was told by a friend who sells/services variable frequency AC drives that a crude sine wave is delivered to the motor after the input power has been converted to a crude DC. I'd contact manufacturer's to see what they would share with you.
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