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jlandon13399

Electric Clock and Modified Sine Wave Inverter

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First time "dry Camping" at the Good Sam Rally in Phoenix. Had coach on inverter power and plugged in my electric clock at 12:30 PM. Checked it at 1:30 PM and clock was reading 2:35 PM. Called Magnum and had a great discussion with a tech named Glen. Found out that there was nothing wrong with my inverter. The clock does not like modified sine wave. The microwave will also run slower but will not be damaged. It does make a different sound on inverter. TV is not hampered at all by modified sine wave. Just posting this so other readers will understand and not go through what I did.

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AH, Yes-Thanks for posting-never thought about it.

Clock did not see a true sine wave - the wave is clipped at the top so clock was reading the square corners as a reference and calculated 120 cycles per min.

Battery clocks have an internal crystal for a reference.

Sound difference of the microwave due to slower fan speed and the power output of the Microwave will be reduced by 15 to 20 percent.

Rich.

Edit-2-28-2015. This link might help understand the real difference.

http://www.xantrex.com/documents/tech-doctor/universal/tech1-universal.pdf

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A modified sine wave will fry the electronics on some appliances. We destroyed two Mr. Coffee machines with the one on our previous coach before we figured it out! Mr. Coffee with clock and automatic start capacity didn't like it, bare bones Mr. coffee worked fine. A number of residential refrigerators don't like modified sine either.

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A friend killed two newer electric blankets with a MSW inverter. It seems to bother the newer ones with electronic controls but not the old ones with bi-metal thermostats.

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Everready to the rescue! :)

I'd wager that inside the electric clock is a little built in ac to dc converter. Finding the right voltage and making a batter box would be fun, but a battery operated clock is about $6-12. Or, go hog wild and get one that will wake to music, news, and even put you to sleep with noise, waves, etc.

It's hare to get rid of the favorit clocks though.

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I purchased a small sine wave inverter(400 watt) to run the smaller electronic equipment or electronic controlled items. Like laptops, notebooks and printers, also works good to charge cellphones.

As long as the load is no greater then 200 to 250 watts, one can use the 12 volt accessory outlets in most vehicles.

Running items with higher loads-one needs to install a 12 volt circuit with larger Gage wires and fuses to meet the current demanded to operate inverters with outputs of greater then 200 Watts.

Items like refrigerators and electric blankets that draw higher current levels require higher wattage inverters, they can be connected in parallel with a MSW inverter(DC input) and serve as a good workaround option.

Rich

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Parallel on the dc input side, PLEASE don't try to parallel the ac output. PSW is wonderful but still pricey, as Rich points out the second PSW for necessary items is a good idea.

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Keep your eye on me Kay!! Thanks for finding a possible issue- Kind of mentioned installing the correct wire size and fuse, but it was a little vague.

Rich.

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