Thor Forums

[Thehobe1]

Originally Posted by Tfryman

Actually, it's motors that don't like the MSW inverters. Most electronics just take the AC and rectify it to DC anyway so the MSW makes no difference UNLESS it is cheap electronics with little or no filtering of the rectified DC output. With poor or no filters the high frequency harmonics get through and mess with the DC circuitry.

I agree with your comment on motors which will run hotter with the Modifed Sine Wave (MSW) power source but I disagree with the comment on electronics.

I have spent 15-20 years designing IC's used in switching regulator applications such as computers, radio, TV and other industrial electronics. I am somewhat familiar with many, as you say "and rectify it to DC anyway" applications and the circuits used in them. The typical "cheap" AC to DC designs use circuits that WILL be more trouble with MSW. First, the input rectifiers and capacitors will have to deal with more ripple current that is hard on the input capacitors (ESR). Secondly, the DC to AC within the general electronic items will have to deal with a fair amount of input ripple current (at ~60 Hz), resulting in potentially higher frequency harmonics that you describe. The MSW could potentially damage the electronic items (some manufacturers actually specify NOT to use MSW power for their units and that it will void any warranty) and certainly will reduce the lifetime of general electronic items.