Aboutcleggsan Expertise All technical areas of Electronics Engineering.
Experience BSEE, MBA, Design, R&D, University Research.
Senior Life Member of IEEE. Life Fellow of AES.
Organizations IEEE, Consumer Electronics Society, Audio Engineering Society.
Broad teaching experience; work experience mostly in consumer electronics and conversion from analog to digital technologies. Pioneer in digital audio at all levels.
Question QUESTION: I have a cabin with avail. power. It is wired like a normal home w/200 amp service box. There is a 9pk. of 12v batteries connected to the service box. I am afraid to connect my appliances to this circuit. How can I get a usable AC power from this pack? I was told by a freind that I should build a astable multivibrator to create a sort of alternating current. Could this work and if so How? Is there a site maybe that has the plans for a high voltage multivibrator that would work?
ANSWER: Are you sure there is not already installed a dc to ac converter in the cabin and the outlets are 117v ac? Have you checked it? And, is there not a means of charging the batteries?
What type of electrical outlets are used in the cabin wiring? If they are the typical 3 prong power plugs used in conventional homes than there is likely AC coming out. If the outlets were DC the plugs would be a different shape/connection.
In any event, there are many, many commercial types of converters that will give you AC output from the DC supply - up to the limit of the wattage capacity of the battery supply.
Here are some that convert 12v dc to 120v ac at low wattage all the way up to 6,000 watts. And, they are not expensive. You can google for many others of similar design. To use a 12v inverter supply you would need to wire all the batteries in parallel. If you left then in series for 108v you could also find similar inverters for ac operation.
And, yes, these inverter boxes are nothing more than a multivibrator that operates close to the 60 hz line frequency so that you get an output that is very, very similar to the power line in your home.
Let me know if you have further questions.
C
---------- FOLLOW-UP ----------
QUESTION: I have checked and there is not any kind of conerter or inverter in the system. All of the plugs are standard three prong recpticles as in any home. I really don't want to use an inverter from 12vDC to 110vAC as they seem to be rather expensive for a high wattage unit and I have been unable to find inverters in my area retailers for 110vDC to 110vAC. Do you know who might carry such a critter or where I could find plans to build my own?
Answer The cost of 110v dc to ac inverter would be around the same cost as the lower voltage.
You did not say what capacity the batteries are and if they have means of being charged; if you intend to connect high wattage devices to the system you must have really big batteries!
And, have you explored the use of dc operated appliances?
There are a few "build your own" inverter projects floating around the internet; it is a good experience if you are wanting to learn about electronic circuits but don't expect it to save you any $$. As a Ogeneral rule building your own will be more expensive than buying one already made (exception is buying one off eBay or craigslist or such places). Why? Building your own puts you at retail price for all the parts. The manufacturer buys the parts is great quantities and pays only 1/3 to 1/10th that of retail prices. A power switching transistor, for example, might cost you $10 or $15 at Radio Shack whereas the equipment manufacturer pays around $.50 to $1.00 for the same unit.
I actually would prefer you to use a 12v system. Why? Because when the batteries are in parallel they can produce high current and even if one battery goes weak or even needs to be disconnected when a cell goes short you are still in business. But, if they are in series and one battery goes sour you have to shut down the whole system until the bad battery is replaced or rejuvinated.
OK. Here is a 12v inverter that can be scaled up in wattage if you are intent on building your own - or at least studying that option:
Building your own would not include the fancy enhancements that a commercial unit would have like accidental short circuit recovery and voltage regulation with rapidly changing load currents and switching transients.
Wishing you the best. Keep in touch if you need more advice.
