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 Post subject: Ideas for a 12 - 13,5 VDC to 12 - 13,5 VAC inverter?
PostPosted: Oct Mon 04, 2021 12:08 pm 
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Joined: Apr Fri 28, 2006 12:46 pm
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Location: Düsseldorf/Germany
Ho folks!

I need a simple schematic to invert 12 - 13,5 VDC (car battery) to 12 - 13,5 VAC!
Consumption is only 5-6 Watts at 50 Hz!
Any ideas? :idea:
Thanks in advance!

Regards,
SIXMILLION DOLLARMAN :wink:

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 Post subject: Re: Ideas for a 12 - 13,5 VDC to 12 - 13,5 VAC inverter?
PostPosted: Oct Mon 04, 2021 1:31 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Wayside, NJ Monmouth
Do you need a pure sine wave or will a modified square wave work ?.


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 Post subject: Re: Ideas for a 12 - 13,5 VDC to 12 - 13,5 VAC inverter?
PostPosted: Oct Mon 04, 2021 3:06 pm 
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Joined: Jun Sun 22, 2008 2:03 am
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Location: Burke, VA 22015
A couple of options, depending on what you need:

1) If square wave is ok and the AC load is floating, an H-bridge driven by a square wave will likely do the job.

2) If the AC load is grounded, an 1:1 isolation transformer can be added to option 1. Since no off-the-shelf 12 V isolation transformer is available, one option is to use a 120V:120V transformer with 10 times the required wattage. For 6W at 12VAC, the transformer must have 60 VA min.

If frequency accuracy is not a concern, a Royer oscillator is a lower cost option.

3) If a sine wave is required, a LC filter can be added to option 2 to eliminate harmonics above 50 Hz.

4) Instead of option 3, a lower cost option for sine wave output might be to use a BTL power amplifier, such as the 7.5W LM4950 driven by a 50 Hz Wien bridge sine wave oscillator to max. output voltage before clipping, which drives a 60VA 120V:120V transformer such as the Hammond 187E20. Since the LM4950 can only swing to 11V max. for 12V power supply, a higher VA transformer may be needed to get 12VAC at full load of 6W.

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 Post subject: Re: Ideas for a 12 - 13,5 VDC to 12 - 13,5 VAC inverter?
PostPosted: Oct Mon 04, 2021 3:31 pm 
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Joined: Apr Fri 28, 2006 12:46 pm
Posts: 1130
Location: Düsseldorf/Germany
Thanks, it will be option 4!
I need a clean sine to power a DUAL record player motor.
Do you have a schematic for option 4?
Or maybe someone might know another simple way....... :?

Many thanks in advance,
SIXMILLION DOLLARMAN :wink:

_________________
From all the things I ever lost I miss my mind the most
ScottyBeamMeUpThereIsNo 4/3-TV/AM OnEarth


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 Post subject: Re: Ideas for a 12 - 13,5 VDC to 12 - 13,5 VAC inverter?
PostPosted: Oct Tue 05, 2021 1:31 pm 
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Joined: Jan Thu 16, 2020 12:29 am
Posts: 1784
Ken Reindell sells some interesting frequency converters used to run vintage turntables.

Unless you really need to run your 50Hz turntable off 12V DC, you could run the output of one of these chronos converters though a 115/12V stepdown transformer:

https://www.kccscientific.com/product/1930/

I think the wall adapter that these run from is low voltage DC, you could email them and check.


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