Computers, Physics and Science

Research Project in Ultra High Vacuum Physics Part 1

This is a high science project done out of my sheer wish to learn. I desire no monetary gain, this is not a college project nor is it aimed at any specific goal. This is a personal project that was simply started out of my desire to understand the nuance and complexity in the various subjects of physics you typically only get to see in universities.

I learn in many ways, but actually doing physical projects that require me to expand my abilities teach me the most. I took interest in this project some years ago after seeing a video of Ben Krasnow’s on an ultra high vacuum system used for an electron microscope which he has also used for DIY sputter coating to make conductive glass. This project was very far outside my realm of possibilities and experience at the time, so I decided to start my own project from the ground up, engineer every part and work out every issue on my own to expand my knowledge of engineering and science. You don’t just learn from the research I want to do with this project, you learn so much about engineering which you can apply to other parts of your life.

Other people have done projects like this before, but I want to do this as professionally as possible, as if I was doing this in a university setting, so I can learn as much as possible, on a very meager budget.

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This project is intended for multiple uses, and is designed to be partially modular to enable a variety of experiments to be carried out. The first proof of concept experiment of this system will be a Farnsworth Hirsch Fusor. This system will be able to achieve a very high level of vacuum capable of making a very functional fusor. The Vacuum chamber’s upper window will be exchangeable to set it up for different experiments, for example, when set up as a fusor there will be a high voltage feedthrough in the upper window for the inner grid and Deuterium gas backfill.

Another use for this project could be for coating glass with metal via the sputtering process to create DIY LCD panels. Creating thin film transistors, or partially silvered and fully silvered first surface mirrors for use in laser systems.

 This Ultra high vacuum system utilizes a retired 4 inch water cooled Daia DPF-4z oil diffusion pump and 2 stage rotary vane pump to achieve very high levels of vacuum. The Diffusion pump is majorly overkill for this project, but it was found for a great deal on ebay, and was impossible to pass up.

The Rotary vane pump is a harbor freight special pump, made by US general. It isn’t the highest quality pump, but it will be operated relatively rarely, and only used to pump air, and not refrigerants as it was originally intended.

A Varian 841 vacuum Ionization gauge was acquired on ebay for a small price is questionable condition, with the intention of repair as sub small project. Repairing old equipment like this and integrating into your designs are a great way to learn about how to fix electronic devices and engineer your own!

The actual vacuum chamber is a CF flanged tube from a larger system also acquired from ebay, but as we do not need a large chamber volume, this small chamber will work perfectly.

There is also a cooling system for the pump, various electrical work, an adapter plate that needed to be machined to interface the pump to the standard CF flange chamber.

The most integral part of this system is the diffusion pump, used to increase vacuum levels farther than mechanical means can achieve. A roughing pump, the US General rotary vane pump pulls the initial rough vacuum needed in the chamber and the diffusion pump, and the diffusion pump then activates as the second stage, increasing to the final vacuum level.

This specific diffusion pump operates on the oil diffusion principle for gas molecule removal, by which in the bottom of the diffusion pump, oil is boiled and vapor travels up the chimney, and the vapor is ejected out to capture as many gas molecules as possible, and fired downwards towards the outlet of the pump to carry the gas to the mechanical vacuum pump. Now, we do not want this oil splashing into the main chamber, so there is a liquid cooled baffle used to cool and condense the oil before it can get into the chamber.

To mate this Japanese made pump to the standard CF flange chamber, I needed to engineer an adapter plate out of aluminum. I used a CNC machine to mill out a plate of MIC-6 toolplate to keep a perfectly flat surface, as the o-ring mating surface needs to be perfectly flat, while supporting the weight of the pump and chamber.

The system after being adapted then needs to be mated, the pump head has an o-ring groove for sealing against the bottom of the plate, and the plate has a groove machined to seal against the bottom of the vacuum chamber. High vacuum grease is used to properly seal the o-rings against the mating surfaces. The diffusion pump then had its outlet tube modified to connect to the roughing pump.

This diffusion pump is large, and subsequently liquid cooled, so a water cooling system must be utilized. I made a water cooling loop by modifying and reusing an old office water cooler, and adding a pump and cooling lines to connect up with the diffusion pump. This water cooler has a stainless steel bucket that contains the liquid, in this case methanol, with the copper refrigerant coils wrapped around it, and a ceramic pump that pumps the cooled liquid around water jacket of the diffusion pump, and then returns it to the bucket to be cooled again.

The water cooler was picked up from its way to the dump, and was modified in the following ways, the entire cooler was shortened to half its height by folding the coils over on the back of the unit, and the entire system was cut in half, removing the water filter unit. A small water pump from eBay was installed, and plumbed into the system. The electrical system was then modified to power the pump when the cooling is on, and the thermostat turned down to prevent overcooling.

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CDMA iPhone 4 logic board FPC dock connector pinout

I searched for many hours to find the pinout for the Verizon wireless CDMA band iPhone 4 so I could connect an old logic board directly to my computer via usb, but unfortunately found no such information. I ended up digging around for the logic board schematic and found the page that contained the pinout for the connector, and traced all the ground pins to find the pin order and orientation of the connector.

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Minolta MD photography

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Minolta MD lenses on Canon T3i

I recently adapted a couple of old 50mm Minolta MD mount fast prime lenses to my canon T3i with the help of a fotasy brand CNC machined adapter with a couple of glass elements in it to make up for the flange distance and aps-c sensor size, the results were truly quite amazing. This lens is manual focus only, and quite a narrow field of view, so getting the shot you want can sometimes be a bit of a challenge, but when you do get a shot, the bokeh is very soft and pleasing, and the depth of field is incredibly shallow.

As you can see, the results speak for themselves. The details are relatively sharp, but the bokeh is very soft due to this lens very shallow DOF

 

Not bad for 12$ 🙂

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DIY X-Ray Source

This is the final product of my DIY zvs x-ray experiment, A full demonstration video that shows a ZVS flyback driver powering a beam triode in a cold cathode configuration, resulting in x-ray emission above 18,000 volts. The resultant X-rays emitted from this tube are just above the minimum energy level the SBM-20 Geiger tube can detect, which is around 1 keV. Because of this, these x-rays are what are known as soft x-rays, which are mostly absorbed by the leaded tube glass. The x-rays that successfully penetrate the tube glass carry on for around 10 feet before my Geiger counter is no longer able to detect above background. The tube glass glows a beautiful blue color as it fluoresces, and the resultant detected x-rays lie in the 2000 CPM and 18 uSv/hr zone, which varies with distance. I believe these x-rays are too low energy to activate my x-ray cassette, which is used for photographing broken limbs. The substrate of the cassette is DuPont Cronex Super Pan-O-Screen. With a number sequence 022309 following. The soft x-rays produced are quickly attenuated in water and air, resulting in 10 foot carry distance and also necessitating lead shielding, since the body is mostly water, the x-rays attenuate fairly quickly in skin, therefore making it impossible to image with this system due to none of the x-rays successfully penetrating your body and instead all being absorbed. I wear a lead lined radiology jacket when experimenting, which completely blocks all radiation exposure from soft and hard x-rays.

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PowerNAS Pentium (PowerMac G4 ATX Casemod)

So I had an old Powermac G4 laying about and decided, hey, it looks pretty cool, maybe I should casemod it! I needed a NAS, (network attached storage) and figured I would try giving this old mac a new lease on life with a paint job, some metal hacking, and a micoATX motherboard! This was a ridiculously over complicated case, I suggest people stay away from the g4 for modding, unless you really like the way it looks, as it was not particularly difficult, but a real pain to get working correctly. I was also doing this with extremely limited set of tooling, that being; a drill with dead batteries, shears, a hammer, and jb weld, since all of my more useful tooling was packed away. (hint, a drill press would have been FANTASTIC.)

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First came disassembly, and anyone who has taken one of these apart will know how non-intuitive it is when you first try it. The Motherboard is held in with small hooks that grip the sides of the mounting holes, while a few screws lock it in place, the cpu cooler is held on by VERY sturdy clips and bolts, and the cables are routed in such a way it takes some serious force to separate them. Then comes the plastic case parts, these are a nightmare, it took me hours to get this thing apart the first time… Four bolts holding in the panels PLUS really tough clips?? Apple really makes some insane gear, as this thing is a safe, it even has a lockbar! After finally taking it apart I put it aside while I searched for some nice surplus computers that were NAS worthy.

System found! I located a 2010 vintage DVR computer for television recording with some decently grunty internals. What was inside was a microATX Jetway m15-g41sgmd3-lf with an Intel Pentium Dual core 2.7 GHz Processor, 1GB DDR3 RAM, and a stock cooler. The power supply was an insanely oversized 560 watt AcBEL unit, and it also came with extra sata cables, and a few other bits and bobs. Score! especially for free!

I then began the process of painting the plastic parts, which was, and still is, a nightmare. I used a valspar paint+primer in black and white, however it was an extremely weak paint, boasting little protection from the elements, therefore, a clear coat was added. Unfortunately, the clear coat destroyed the paint job, rendering the black painted parts uselessly milky. Fortunately, I had a black rustoleum paint+primer that was stronger and somehow matched the valspar. Unfortunately, it is still just paint and already has chips in it. Moral of this story, spray paint is a waste of time more often than not, but either way, it still looks fantastic for what it is, much better than the horrendous clear grey and blue that it used to be!

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Mounting the ATX hardware was not necessarily difficult, but also not very straightforward. The power supply required me to drill a network of holes in the side of the case so it could somewhat properly intake, and the motherboard required careful placing of the mount points so the pci slots would line up properly with the board. I also had to deal with narrow windows for cable routing and cooling, as I still wished to use the stock disk drive tray and fans. A notch had to be cut out of the disk drive tray to accommodate the ATX power connector, and the original IO shield needed its rivets drilled and removed so the IO on the ATX board could be used. To cut the shield off from the pci slots, I simply drilled holes in a line and snipped it off. When everything was ready I carefully positioned the board and jb welded the standoffs to the base plate. The disk tray was hen put in, wires tied, and a power button made. I also decided to omit the case latch since when i found this mac the latch plate was broken and i did not wish to integrate it into the ATX design.

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A Beautiful Old Processor; PowerPC XPC7400

Is it an Intel? An AMD? No! It’s a PowerPC Motorola XPC7400 from a PowerMac G4! I have never owned a mac, and when I got this old G4, I immediately disassembled it and was surprised by this nicely engineered processor daughter board,a nice contrast to the normal socketed processors. shame apple dumped powerpc, it’s always nice to have something a little different from x64/x86.

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