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300W boost converter project

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oztules:
(blank)

drdongle:
So tell us Oz, how did you fill it?

dinges:
I feel robbed; shortchanged; etc. ;)
Peter.

WXYZCIENCE:
The wind knocked over your barbwire phone connection? Joe

oztules:
Made a boo-boo here and the diary went up.... with no stuff in it  oh well.....
Is was one of those days where it was too windy/cold to venture outside and I decided to tidy up my boost experiment.
The ratsnest was spreading over onto the floor of the shed, and it was time to dust off the big computer and do a citcuit board for this converter.
After finding the disks for the Autotrax and loading them into a new windows 98 partition, it was time to relearn how to use the program again (long long time).
This program is free now and can be obtained from http://www.airborn.com.au/layout/easytrax.html
along with some improvements (thanks to Commanda).
After struggling with making a rudamamentry library of components, 3 hours later I finished up with a board like this:



Its not done by an engineer so you get what you get... time to print it out.
Luckily the program had a driver for laser300dpi and the old brother 730 I had bought across with me had just enough toner to print a page or two. (Moving onto an island is just so much fun).
I print it out on two transparencies (o/head projector sheets I think). I use two because this printer is pretty bad, and the toner is very low. I moved the image on the transparencies to different physical locations so that the flaws in the drum appear at different places on the layout.  very agricultural yes?
By taping the two transparencies together (on top of each other )we get a image that is mostly black where it should be in two layers. Any drum deficiencies only effecta single layer at differing places, so the theory was that tracks would be mostly covered.
This worked out as pictured here:



After rummaging around through the container outside, I found the picture frame I wanted and removed the glass from it, found the ammonium persulphate and breathed a sigh of relief..... over here you can't just go up to the shop. I've been waiting for a month for my fiberglass to turn up for a stator....still waiting.
So being lazy, I had gotten some pre-sensitized pcb boards from Wiltronics (on the net) and proceeded to sandwich the transparency between the green presensitised board and the glass from the picture frame.
Bewdy, now all I need is a UV light source. A flourescent for 20 minutes at 2" (havent got one out in the shed) or exposure to the sun for 1 minute or so.
So we wait for the sun to come out..........not coming out.....now its's raining again....bum.
The nice thing about oceanic weather is the complete unreliability of the weather. Its still raining, but now the suns out at the same time. I hold the board to the sun whilst standing undercover for 2 minutes....seems a long time to stand still and all the while thinking..... gosh this is high tech.
Now to develop the board.......oh no, can't seem to find the NaOH. When this happened  on the mainland we had a dishwasher, and the powder for it was caustic, and could be relied upon to act as developer....a shed ion the middle of a paddock does not have a dishwasher. A quick test with the clothes washing powder yeilded no result...damn people frendly wash powder.......I did the unthinkable............
Went in and had a cup of coffee and brewed over my delimma....The good lady wife suggested oven cleaner......silly women..bloody oven cleaner that won't work says me...
It was ten minutes later that I looked with satisfaction at my nicely developed board:



sheepishly went back in to inform she who must be obeyed that she was right, and I was wrong.....some days it don't pay to get outta bed.
Scrabbled around the shed looking for a suitable container to etch the board in. It must be corrosion-proof, disposable, tough, and I decided a 5kg plastic nail box for 4" bullethead nails looked perfect......soo out they go.
Armed with the newly aquired "etching tank" I added about a tablespoon of ammonium persulphate to 1/2 inch of hot water, and dumped the board in.
I sloshed the board around in the mixture for ten minutes.......I've had enough, it's too slow.....add more ammonium persulphate.....little bit more.....now I can see it peeling off (small exaggeration). it's almost done:



Note the lovely yellow nail container (i mean etching tank.).... Decided that makes it go faster.



Well half the day is gone and we have a board that needs drilling.  It was some time later that I found the minidrill, and importantly the mini-bits that go in it,and filled the desktop with another bunch of tiny holes. I have discovered that the drill drills quickly through the fibreglass, and that the trusty bench is at a different rate and sound so I know instinctively to move on to the next hole.. Good for me ..not good for the bench.
Well the next hour was used to load the board as per this overlay:


There is no trick to this, I use an ic holder to take the tl494 so that if I destroy it in testing, it is easy to replace. The coil is stolen from the original one I built a few days ago (50t ETD39)

It ends up looking like this:




I'l post this now as no doubt I will have been on the end of some barbs  by some for the blank post:)
................oztules

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