The problem is that even though I have a whole-house generator, many devices (clocks and cable boxes) lose their brains in the 15 seconds it takes for the gen to kick in. For a while I have been pondering a small (<10 W) ups project to sprinkle about the house, because I have six 6 V SLA (sealed lead-acid) batteries and a butt-load of electronic components. Of course, per my license plate, it should be a true-sinewave device. This should be more than enough to run a resurrected old digital clock in the garage, the dvr cable box, etc.
This idea might not be new, but it came to me in a flash of lawn mowing: an ebay 10 W class D mono amplifier module as an output transformer driver. Crystal oscillator, binary divider with the last few stages driving stepped resistors to create a 5% distortion sinewave, little lowpass filter, class D module, 6.3 V filament transformer, 115 Vac output. No load switching at power-out - the circuit would be running constantly, with the oscillator/divider being reset constantly by the incoming power line so there is zero output disruption when power fails.
Is this a way to get a true sinewave, online UPS, at near stepped squarewave efficiency, without designing a switching inverter stage from scratch; or am I missing something? Assume I've got the AC input power stage covered.
Thanks.
ak
This idea might not be new, but it came to me in a flash of lawn mowing: an ebay 10 W class D mono amplifier module as an output transformer driver. Crystal oscillator, binary divider with the last few stages driving stepped resistors to create a 5% distortion sinewave, little lowpass filter, class D module, 6.3 V filament transformer, 115 Vac output. No load switching at power-out - the circuit would be running constantly, with the oscillator/divider being reset constantly by the incoming power line so there is zero output disruption when power fails.
Is this a way to get a true sinewave, online UPS, at near stepped squarewave efficiency, without designing a switching inverter stage from scratch; or am I missing something? Assume I've got the AC input power stage covered.
Thanks.
ak
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