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| #Post#: 27-------------------------------------------------- | |
| Big LJL Aircore | |
| By: admin Date: March 22, 2013, 7:48 am | |
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| Here is a picture of the big LJL Aircore Transformer inspired by | |
| the SJR3.0. It is going to El Paso TX for the RV Show there in | |
| April. It is 26" long and 4.5" D. I have had it running 16 | |
| bulbs on 4 amps and the transistors don't get warm. It has an | |
| on/off switch, Hi/Lo switch and a 10 amp fuse. | |
| There are 880 secondary turns of 18 awg magnet wire, and 120 | |
| turns of 10 awg wire. Two 2N3055 transistors are in parallel | |
| with a 1 Ohm resistor across the Bases to balance the frequency. | |
| On high all three secondary windings are used. On Lo two | |
| secondary windings are used. The low setting is enough to work, | |
| read and feel comfortable. The high setting is blazing bright. | |
| The design is sort of "steam punk". It can be wall mounted or | |
| laid next to the 12 volt battery. | |
| [attachment deleted by admin] | |
| #Post#: 1322-------------------------------------------------- | |
| Re: Big LJL Aircore | |
| By: Rooth Date: January 23, 2014, 3:45 am | |
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| Hello! We show and your new project ? | |
| #Post#: 2055-------------------------------------------------- | |
| Re: Big LJL Aircore | |
| By: JonBruno Date: April 2, 2014, 11:13 am | |
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| I was trying to run the numbers to see what I'd need if I was to | |
| build one. | |
| I have a question about the secondary windings... | |
| You used 18 awg mag wire but when I run the numbers on a 26" | |
| core I come up with only enough room for 622 wraps of 18 awg | |
| (.0418) | |
| even at it's nominal bare wire diameter (.0403) I can still only | |
| see that 645 wraps would be possible.. | |
| However if you used 21 awg that would more likely jive as it | |
| comes in at 849 wraps at .0306 maximum outside diameter and 869 | |
| @ .0299 min (closer but still not 880) | |
| I'm not sure if my problem is my awg chart is wrong or if you | |
| have a longer tube or does the coil just double back on itself? | |
| ORRRR is your 880 wraps the total of all three individual | |
| secondaries? | |
| I'm definitely missing something here... but I'd like to | |
| experiment. | |
| Thanks for putting up with my babbling. | |
| #Post#: 2056-------------------------------------------------- | |
| Re: Big LJL Aircore | |
| By: lynx wind Date: April 2, 2014, 1:40 pm | |
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| I no longer have the Big LJL. I am pretty sure it was all three | |
| windings add up to the total. If I were to do it again, I would | |
| shorten the PVC a bit to calm down the ratio to closer to 6.8:1. | |
| That big LJL was close to over driving bulbs. It would light | |
| up several bulbs off a 9 volt battery blazing bright. | |
| You have the right idea. I measure how many turns I can get per | |
| inch with a awg wire. Then I measure how many turns of primary | |
| I get. Then I adjust the length of the PVC until the ratio is | |
| about right. There is something special that happens with the | |
| several layers of parallel wound secondary. Much more work but | |
| really good performance from an aircore. | |
| #Post#: 2168-------------------------------------------------- | |
| Re: Big LJL Aircore | |
| By: JonBruno Date: April 8, 2014, 1:01 pm | |
| --------------------------------------------------------- | |
| Ahh, Like the LJL-SC 100 / 14.7 | |
| one question arises, if I was to upgrade the wraps to 200/29.4 | |
| what gains would be achieved if any? | |
| What would be different? i.e. amp draw, oscillating freq? | |
| If at 12V at 6.8:1 does it test at the secondary as 81.6v? | |
| I get the correlation of the ratio between the pri and sec.. but | |
| I'm not sure what determines the number of wraps you choose to | |
| go with? | |
| I guess awg may play a role? maybe amperage? space constraints? | |
| This is where my education in transformers 101 is lacking.. | |
| #Post#: 2170-------------------------------------------------- | |
| Re: Big LJL Aircore | |
| By: lynx wind Date: April 8, 2014, 1:53 pm | |
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| Jon, | |
| My theory with the Big LJL was that by using heavier wire and | |
| two transistors I could power more bulbs. Didn't really see any | |
| difference up to 12 bulbs at which point I didn't have more | |
| bulbs. I think the reason it was so blinding bright is that I | |
| had a pretty "hot" coil ratio, not because it was big. | |
| I think the 4" coil works very well, but you will have to | |
| experiment and wind neatly. Then tune to your liking by adding | |
| or subtracting primary turns. | |
| The reason I use 100:14 is so I can stuff all that wire in a | |
| $2.49 ferrite choke. | |
| Honestly, go to Radio Shack and buy their magnet wire pack for | |
| $7.89, a transistor (or two), a ferrite choke. Wind the entire | |
| spool of green wire around a plastic butter container. Then | |
| wind the 22 wag on with 11 turns, come out with a loop and then | |
| wind on another 7 turns. The loop will be the positive | |
| connection for high, and the longer end will be positive for | |
| dim. | |
| Use a center off SPDT switch. Run the positive to the center | |
| and the loop to one connection and the longer end to the other | |
| connection. Now you have center off, up for HI, down for Lo. | |
| You will find that this will light many bulbs. | |
| #Post#: 2176-------------------------------------------------- | |
| Re: Big LJL Aircore | |
| By: JonBruno Date: April 8, 2014, 8:09 pm | |
| --------------------------------------------------------- | |
| Thanks for the info. | |
| I had some wire left over from an old bedini generator project I | |
| had build a few years ago. | |
| I wrapped the old 68/10 coil because of the limited mag wire I | |
| had. | |
| It lit up nice and bright on a 12v ryobi battery from my drill. | |
| Here I tried to fire two bulbs on a 9v. I just love the novelty | |
| of running 110v stuff on little power sources. | |
| Lots have changed since the old Fuji days. | |
| And the CVS stopped giving away the camera shells anyway. | |
| http://i883.photobucket.com/albums/ac39/sigmaz/Mobile%20Uploads/2014-04/2014040… | |
| I'll get some more supplies tomorrow and try your suggestions. | |
| Thanks again! | |
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