down dirty inverter advice needed

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dacflyer
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down dirty inverter advice needed

Post by dacflyer » Wed Jun 29, 2005 9:38 am

hi all..i had a brain stormlast night..OW !
i hate using coleman lanterns when going fishing at night.
with all these power efficient spring flourescent lamps out now.i want to be able to make it possible to light one from a battery..but carrying a large battery and a power hungery inverter does not sound too appealing.
i was wondering what would be the simplest way to make a small inverter to drive one of these lamps.
looking for somehting less than 40 watts at 120 volts. and i am guessing it will have to be about 60hz..
is it possible to use a chip that makes a sine wave,,and it drive a FET and then a small 120v to 12v transformer??
or is there somehting out there this small and cheap?? smallest inverter i am able to find is 140 watts??<p>end.

Mike
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Re: down dirty inverter advice needed

Post by Mike » Wed Jun 29, 2005 9:55 am

As I've said before in other posts, I'm not a flourescent lighting expert, but I have a small inverter that powers flourescent lights from a 9V battery. I pulled it out of a dead scanner, along with the small light in there. I don't know if it would work with bigger lights, but if you have or can get a dead scanner with a functioning light, you may want to try the inverter from it.

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Dave Dixon
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Re: down dirty inverter advice needed

Post by Dave Dixon » Wed Jun 29, 2005 11:11 am

Ray,
I have had good luck with the following company...
CCF bulbs and inverters
They either sampled, or sold me quantities of one (I forget which). Check out their CCF bulbs and inverters. I used one for an aircraft graphic (No Smoking/Fasten Seat Belt) that ended up in continuos <sp> use in my car for years now( just when the ignition is on!!)
I don't remember the current requirement, but it seems like it was really reasonable. They use(d) the same technology in laptop displays. I'm pretty sure an array would put out a bunch of light.
Hope this helps,
Dave
BTW, the inverter was about 1 cubic inch in size.<p>[ June 29, 2005: Message edited by: Dave Dixon ]</p>

Tommy volts
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Re: down dirty inverter advice needed

Post by Tommy volts » Wed Jun 29, 2005 11:34 am

Why is the device called an "invertor"? What is being inverted? Is there a better word for what the device is doing?

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Dave Dixon
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Re: down dirty inverter advice needed

Post by Dave Dixon » Wed Jun 29, 2005 11:51 am

An inverter coverts DC voltages to AC voltages. Kind of the opposite of a rectifier which helps to convert AC voltages into DC voltages. An AC voltage usually has a portion of its voltage (alternates of course) below ground or nuetral potential. I guess that's why they call it an invertor, as that part of the DC input voltage must come out inverted after it's converted!
If you are more confused than ever.... wait till someone else jumps in with a better explanation!
Regards,
Dave

Tommy volts
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Re: down dirty inverter advice needed

Post by Tommy volts » Wed Jun 29, 2005 5:04 pm

Dave,<p>That is a perfect explanation. Thank you.

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sofaspud
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Re: down dirty inverter advice needed

Post by sofaspud » Wed Jun 29, 2005 5:24 pm

What is a "spring fluorescent lamp"?
I've seen several DC-powered circuits for fluorescents on the Internet, though I've never built one. I have a couple of 12VDC fluorescent lanterns. One uses two 6V batteries and the other is rechargeable. Neither appears to have complex circuitry nor are they particularly heavy.

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Chris Smith
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Re: down dirty inverter advice needed

Post by Chris Smith » Wed Jun 29, 2005 5:47 pm

Most fluro drivers run at 40,000 cycles or faster, 600 plus volts<p> This way there is no need for the wasteful heater elements at the ends of the lamp, which consume 80% of the power on house units. <p>What you need is a HF oscillator, and a FET driver,... stepping up the voltage from 12 volts to 600 volts or more, at 40K plus cycles.<p>The lamp will light on its own and be brighter than the standard power supply, and if you do your design right you can run a 22 watt bulb so bright you cant stare at it while drawing less than ½ amp, meaning that your using 6 watts and getting around 75 watts worth of actual light equivalence. <p>If you cant get it under one amp, you didnt do a good design and it needs to be tweaked. Pulse width, length, and voltages are critical. Play with them all. <p>The best bulbs to run are the little skinny RV lights, 18 to 22 watts, about 18 inches long by about ½ diameter. <p>It has a nice blue light in color, or white.

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Re: down dirty inverter advice needed

Post by 2M MACHINING » Wed Jun 29, 2005 9:14 pm

Hi Chris, sounds like you have alot of experience with floresenc lights.<p>I have about 40 of the 2bulb 8 footers hanging in my shop.(I forget the wattage at time of writing)<p>Question is. is ther any inexpensive way to get more light output from them, as in buy or make to replace the existing ballest.<p>thanks
MIKE M

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dacflyer
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Re: down dirty inverter advice needed

Post by dacflyer » Wed Jun 29, 2005 10:00 pm

the spring lamps are the common lamps you see in the hardware stores like home cheapo or Slowes
(home depot or lowes)
they are the compaq flourescent screw in bulbs.
they run on 120 volts.
small compact and very bright for their size<p>i have many of the CCFT inverters , but i am mainly looking to make or find a small inverter
12v to 120v..and around 20-40 watts if possible.<p>the CCFT drivers and lamps i have here,, cannot find a real use for them yet.. the lamps are to fragile to use in a useful way...especially for taking camping or fishing etc.
with the inverter i can at least use it at night off of battery that charges by solar by day.

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sofaspud
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Re: down dirty inverter advice needed

Post by sofaspud » Wed Jun 29, 2005 11:00 pm

Different strokes I guess. The lantern of mine that uses 2x 6V was found along riverbank (sans batteries) in about 1988. No repair needed and the 15W tube was still good. It has been taken along on camping and fishing trips, and used intermittently since 1999 on the same set of batteries. One day I plan to convert it to solar rechargeable power also.

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Re: down dirty inverter advice needed

Post by rshayes » Thu Jun 30, 2005 4:10 am

The small flourescent lamps have a bridge rectifier and inverter built into the base. The rectifiers are usually similar to the 1N4000 series, and are probably reasonably efficient up to a few kilohertz. A square wave inverter that puts out about 120 volts should work. At the 20 to 40 watt level, this could be a simple two-transistor push-pull type of inverter. If the frequency is kept down to the kilohertz range then switching losses shouldn't be much of a problem. You would have to design and wind your own transformer, but audio transformer cores could probably be used. With a little care, the efficiency of this type of inverter should be around 90 percent.

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dacflyer
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Re: down dirty inverter advice needed

Post by dacflyer » Thu Jun 30, 2005 9:05 am

stephen >> could i use a center tapped power transformer as well? run it backwards?<p>12-0-12 to secondary
120-0 primary side
run this in reverse?
any hints oh what type of transistors to use?
regular or mosfets? darlingtons?
thanks.

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jwax
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Re: down dirty inverter advice needed

Post by jwax » Thu Jun 30, 2005 10:12 am

Bipolars (2N3055) would do nicely, but only if you want a project. Add a few resistors, a transformer like you mentioned, a box, maybe a fuse, a power switch, cabling. OR,
http://www.donrowe.com/inverters/newpoint.html
All of $14.
:D

rshayes
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Re: down dirty inverter advice needed

Post by rshayes » Thu Jun 30, 2005 11:14 am

Yes, you can, but a transformer designed for higher frequency (in the kilohertz range) would be smaller and lighter.<p>Allowing a large transformer like that to saturate reduces the efficiency, due to large current spikes as the transformer saturates. This can be avoided by using an additional small transformer for feedback, and allowing the small transformer to saturate first.<p>The design of this type of inverter was discussed in several articles in QST back in the 1960s, possibly you can find a public library that has a microfilm file of old magazines. A public library may have an old ARRL Handbook still on the shelves from this period, and that may have design information. College libraries may also have books on inverter design as well as old Handbooks.

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