Inverter Generator (Follow-On)

why would they waste money on a crystal?

NT

Hello, and what do you mean by "waste'? Microprocessors typically use a crystal as a timebase. While I appreciate all the responses to my OP, It appears no responders have intimate knowledge of the subject internal circuitry. If I did, I wouldn't have posted. The 50 or 60 Hz output of the inverter-generator has to be traceable/locked to some internal time reference, not the rpm of the engine. A crystal seems a likely candidate as I don't think these appliances have an internal cesium or rubidium clock :-) Sincerely,

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J. B. Wood	            e-mail: arl_123234@hotmail.com

Welcome to the filter.

After a quick google, I found this paper.

Design and Construction of 1kVA Inverter

and also

250W PWM inverter circuit SG3524

The mentioned IC SG3524 is primarily intended for DC-DC inverter designs, and the oscillator is programmable by values of R & C.

TI SGx524 Regulating Pulse-Width Modulators

Although in the above two circuits, I see they set the oscillator lower (50Hz) than TI's spec sheet (Sec 7.7 , Fig 2)

Have a look around for SG3524 schematics. It's popular!

3 High Power SG3525 Pure Sinewave Inverter Circuits

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Adrian C

Hello, and thanks for the above link and the others! Looks like those designs depend on R-C time constants rather than crystals. And crystals, like resistors and capacitors can age with time. Whether or not those designs you referenced are employed in inverter generators is TBD. It's not so much an issue which time-base (oscillator frequency) works better when new at room temp but how it behaves in the outdoor operating environment of temperature, humidity, vibration, rough-handling, etc, including component aging. Mea culpa for posting design questions to a repair ng. Sincerely,

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J. B. Wood	            e-mail: arl_123234@hotmail.com

Ceramic (piezo) resonators are a more likely frequency determining element. I'll resist the temptation to tear apart my neighbors Genrac inverter generator to see what it uses. Ceramic resonators have 3 big advantages over quartz crystals:

1. They're cheaper.
2. They're cheaper.
3. They're cheaper. However, for a non-critical frequency reference, such as the 50/60Hz from an inverter, a simple RC time constant with some temperature compensation would probably be good enough.

Conventional gasoline generators usually run at 3600 rpm, which sets the output frequency. Inverter generators can adjust the rpm to match the load and have the inverter section determine the output frequency. That also allows the generator to brushless, quiet, more efficient, and have a faster response to changes in load.

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Youa culpa because you posted a vague question and expected a precise/exact answer. How much accuracy do you need? Call up a few vendors and ask if they can meet that spec over all your environmental conditions and time. Good luck with that.

If you need PRECISE frequency, you'll probably also be unimpressed with the phase noise, or high frequency components of the digital approxmiation to a sine wave.

The reason to have an inverter is reduced fuel consumption under light load. I don't have any specific info, but expect that there are inverter generators that do not have accurate sine wave output.

Your problem is likely much more complex than you think.

People can't help solve your problem if you can't disclose it. Feel free to continue to waste your (and other's) time.

Hello, and I see nothing "vague" about my OP. And I don't think I ever implied I had a "problem" nor that I was attempting to construct the subject appliance. I had a question about commercial design practice and was seeking some info that I thought some folks on this ng might know as a result of either repair experience and/or had seen circuit schematics. Nothing else. Apparently some more polite folks on the ng saw it this way and folks have helped despite my "lack of disclosure". And if you thought it was a waste of your time why bother to respond at all? Judging from your response I think you wasted your time. Sincerely,

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J. B. Wood	            e-mail: arl_123234@hotmail.com

Because, some people, all they have to contribute is to piss in somebody's Wheaties.

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"I am a river to my people." 
Jeff-1.0 
WA6FWi 
http:foxsmercantile.com

Put in a search (12 to 120 Volt true RMS inverter schematic) and got this, right on top.

Complete with nice pictures and scope screen-shots.

Looks like the LM348 does the trick.

Peter Wieck Melrose Park, PA

xact

I can disappoint you then. My answer comes from understanding the principle s behind the designs, which comes from years designing electronic stuff. I' ve never taken such a gen apart nor do I need to to understand why no-one i n their right mind is going to derive the 50 or 60Hz from a crystal. Nor ar e they likely to clock a rock bottom price processor with a crystal.

Everyone has their point of view, and that's all good, but when you have no t a clue and repeatedly criticise those that do, and then criticise peoples ' fair criticisms of you... at least the rest of us can figure out where th at goes.

The crystal filter? A crystal with several electrodes used to filter frequencies?

do you never get fed up with people being stupid?

Do you never get tired of always having to be right, even when you're not?

--
"I am a river to my people." 
Jeff-1.0 
WA6FWi 
http:foxsmercantile.com

that's not the situation here.