Joule Ringer!

[Peanutbutter29]

Sorry to double post, but to make this separate.  I posted 2 videos (one still processing) that shows some improvements for this circuit that should come in handy.

http://www.youtube.com/watch?v=FYL5P4V87Ok

*Fix for the negative bias against the base (potential failure point)
*Fix for the oscillation start up, now starts at 500mV
*Integration for frequency adjust with fine adjustments (raise and lower)
*Integration (in second video) for Capacitors to further adjust frequency (lower of course)

I think the pot connection is pretty key to guarantee an oscillation start and reduce risk of frying the B-E junction.

Thanks

[hoptoad]

snip..
Input @ full light 16.5v @ .47ma (about 8w) lighting 13w fully!
snip..

Do you mean .47 Amps (i.e. 470ma) ??

If you really meant .47ma then your consumption would only be a miniscule 7.755 milliWatts not 7.755 watts, (about 8w) lighting 13w fully!   

Cheers

[Peanutbutter29]

Ya, sorry for the listing incorrectly there.  I started with .47 and and changed to .470ma, but then must have accidentally erased the zero instead of the decimal.
So it was 7.755w

Also, I was able to get 11 of the 7.5W LED bulbs and try getting more power out of the system.  I think everything's covered in the video, but max power was 29.2w for the 82w total bulbs connected (though not quite as bright as connected to 120vac). I'll have to wait until they get more bulbs in to see if I can run more and might need a bigger source;  but the transformer should take a lot, if I can drive it.
http://www.youtube.com/watch?v=-ncciyB6SKc

Thanks

[Magluvin]

Hey Peanut

Did you rewind your transformer as Laser has shown? Or are you using a pre wound unit?

Mags

[Peanutbutter29]

The coil I'm using is from an old salvage out of a 50Kva Laser supply from a local university.  This is a setup transformer (88mh to 480mh), though was not a high power section.  Also the output wires are 600v rated so it was not HV either.  Also, it was 60hz driven and is iron core, so not designed for HF.  The core is a "loop" laminate design.  Secondaries coils are wrapped on either side and the primary is wound AROUND (EDIT 2: it is possible these are wound on one end of the bobbins after looking more) the outer of both coils.  It IS left in stock wind configuration, I haven't changed anything with it.  Just kept it around because I thought it may be useful someday.

I have another couple, more common transformers;  I'll see if I can get those to work also. 

I believe the biggest loss in this design is from the core and low Q.   Since, the only magical material to solve this is restricted to military (heh, metglas);  the optimal design may be difficult to find.
** If we can find ANY amorphous core with a Square BH we're in business!  I have found 3 manufacturers but only contacted Metglas so far, with the usual run-around.  Otherwise there are some square BH ferrites, and then it would be to finding the highest Al and permeability with the lowest core loss per cm2.

I have an E-core coming that's a bit larger, higher Al and more permeability;  with the same core loss per set (overall area) as Lasersaber's.  We'll see if that makes some difference. 

Ultimately though, it seems our max output may be related to the Energy stored in the secondary (primarily in Inductance) and the maximum flux we can impose on the primary (restricted by transistor power, Impedance, volts, etc).  I believe with the Bias resistor we can drive the primary up to our source or transistor Temp max.  So, then it would seem the trick is to attain as high of Q secondary as possible to maximize output. 

just rambling lol,
Thanks

OH EDIT:  The primary is center tapped but not used here.  If you measure the inductance of either half, you get 9mH;  however across the ends is 88mH.  So the primary winds are in opposition (as pointed out in the earlier LED vids with this trans.), least that's my take.  I may have to remove that covering sometime to better see its' construction.