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I made the cannon from aluminum sheet, scaled up some from "Airzooka" toy, and put a large long-throw subwoofer driver. I found the optimum pulse shape to be complicated by experiment (involving a back movement followed by front movement, followed by back).
Problem is that inner beaker will try to float, a lot! You will need lead weights in inner beaker.
The trouble, nowadays, that is not good enough! "Perfectly good" boards twist and bend up into wood only fit for the fire-pit in a few months. The only thing that can't happen is more knots "move in"! What you need at the lumberyard, is a crystal ball!
It is a Tesla coil if the secondary's coupling to the primary is low, and the secondary is resonant. When a relatively large secondary is made, the capacitance to ground tends to dominate, making this a Tesla coil if the primary is driven at that resonance. That is forced as he is using current feedback to the transistor's base.What I would do is add an "anti-parallel" diode (most likely a 1N4148 or 1N914) across the BE junction (cathode banded end to B, anode to E) to carry reverse cycle of AC safely around transistor's BE junction, otherwise transistor could fry. Also a smooth metal toroid or ball on top would improve voltage output, and the E lead/battery minus lead should be grounded.How long of a spark do you get?
It "is a Levitron". Levitron makes a variety of products that levitate magnets, and some of them involve actively-controlled levitation, such as shown here.
Try this method of removing the excess paint: select a solvent that the paint is not compatible with. For the oil-based paints you are using, denatured alcohol is good. Put that on the rag. Apply the paint to the tool, but do not wait for it to dry. Wipe immediately lightly with the rag. What will happen is that the paint will congeal on contact with the (non-compatible) solvent. The paint on the surface will ball up and slide off, like the way dried rubber cement does, but that in the groove will congeal and stay there. I use this technique to "silk screen" circuit boards made on a circuit board router. I first rout the "silkscreen" with a 10 mil cutter 10 mils deep, apply Naz-Dar oil-based silk screen ink with a razor blade, when wipe off the excess with the alcohol rag. Then I proceed with the drilling the holes and routing the traces (I must be careful to not "cut" traces with the silkscreen printing).
After scoring the bottle all around, you can also use tiny hammer blows to start the crack. But the blows must come from the opposite side the score-line is on. Take a piece of #12 solid copper electric wire, and fasten a 1 oz fishing sinker or other heavy small object. Bend a curve into the wire so the sinker can be inserted into the bottle and strike behind the score-line, until you see a silver cast to the line, indicating the crack is started. Work around, tapping at the end of the crack to grow it around the bottle.This is the same method used to cut flat-glass, except for the modification to get the hammer inside the bottle.
You could add 2 fake knife-contacts for additional realism. These could be made of thin spring-brass, fastened to the wood face under where the bars come, and bent into a "U" to just lightly touch the bars when the switch is thrown.To answer to those who have "standard" US switches, the center bar could have a crank that actuates the switch (the axle would be broken in the center with the crank in the center over the switch handle), with lost motion as the switch handle only swings through about 90 degrees, versus the 180 degree swing of the Frankenstein switch.
The smart thing to do is to enclose the ladder in a transparent glass or plastic tube. The ends need to be open to allow air to rise through the tube. This helps the arc rise (the slightest room air currents disturb the arc). The tube also addresses the primary issue: safety.An interesting varient of this is to make the ladder helical.
True, if you allow the liquid in the cell to mix freely. In fact, much trouble is gone to to prevent this mixing to make lye (sodium hydroxide) and chlorine by electrolyzing salt solution.
What I use for the salt is sodium sulfate. It is non-hazardous, and is neither acid nor alkaline.
They are right, you get chlorine gas instead of oxygen.
Hydrogen: cracked from methane (natural gas) or by reaction of coke and steam. Oxygen: fractonal distillation from the air (large quantities) or by pressure swing adsorption (for quantities usually for medical oxygen).
Regarding your comment about changing angular speed versus power draw to the rotating LEDs: I see no reason why there should be any impact at all to the the motor speed. The motor is (I assume) powered by a totally independent power source. The rotary transformer, being totally rotationally symmetrical, causes absolutely no load torque on the motor, (other than the "windage" air friction of the rotating coil, which is constant). (It does not extract power from the rotation). I would have 2 coils, each about the diameter of the globe, with perhaps a dozen turns each, one just inside the other, plane perpendicular to and centered on the shaft, mounted under the base plate; inner one rotating with the rotor, the outer stationary, and driven with a half or full bridge circuit/oscillator from the DC supply in the KHz. The rotating coil's output would be rectified by a diode bridge, and fed to the DC/DC converter you now have.You could also use a coil set with ferrite cores for more compact assembly. If you want to know how to design the transformer, I can explain.(I got a "404 error" on your github link. I tried a search in github on claudiosousa and got nothing)The problem I have with C is that it was designed for PCs, which have basically a big bag of RAM, which is loaded with the program in question, then executed. If the program didn't write something in RAM, garbage is assumed to be there, so you can't "look up" something you didn't write FROM THE PROGRAM. On the other hand, embedded machines have programs usually in ROM, which not only have executable code, but also data ("look up") tables on ROM. A BYTE or WORD directive loads ROM with tables in assembly. C is awkward when dealing with look-up tables, and that is 90% of my programming consists of. (My typical object files are 80% tables and 20% code). C also doesn't "know" about machine-specific things such as the carry flag. The other thing I can't do is debug code WHILE IT RUNS, which I can do with my 65816 and 6808 systems. I could never get the stuff to work if I couldn't do that! For example. Say an interrupt routine "is done". I want to jump back to the debug kernel, so I can debug with the leftover cycles, before the next interrupt comes. Where is the debug kernel? The complicated operating systems don't tell me where or what that is! It is all wonderfully hidden behind all the GUI "eye candy" I don't need! I wish someone could tell me how to do things like this. I would be satisfied with a debugger that can read/write registers, go and stop, a simple assembler, a good data sheet on the processor, and no JTAG peripheral stoppage when in "debug" mode to interfere with running interrupts.
I researched Mercotac sliprings. Regulations prohibit the sale of these to "consumers" because of the mercury content. How did you get yours?
When you create an Instructable, you need to include all relevant details. I saw nothing about this at all (did I miss something?) This is a key part of the project.I built a similar device, much cruder in that it had only 7 monochrome LEDs, but used a rotary transformer (4" diameter close-coupled open-air coils operating at about 32KHz) to convey both power (1/2W) and data (32Kbit/s) to the rotating part. This would have allowed you to eliminate the belt/pulleys and direct drive, as no access is needed at the center or rotation. You must be careful that the center of rotation of the shaft is accurately aligned with that of the slipring, or the slipring will bind and fail.I am frustrated by the "new movement" in processing going to C code only, along with the "baggage" of "operating systems" and libraries such as the Arduino. It is almost as bad as a PC! I found out that an Arduino is slowed by a factor of more then 100 by the "system calls" to set a byte to a port. This precludes using "real-time" code that can function in the microsecond time frame (required for generating and decoding the transformer signals, in addition to operating the display). If I could program Arduino (or other processor) in only assembly with all libraries eliminated, I would pursue more projects like this. Now I am stuck with older processors (6808 and 65816) that are not burdened with all this baggage. I can even debug code while it is running!Where did you get the slipring? Mercotac? What did it cost? (You might want to put this in the Instructable). Did the "mercury police" come after you? what keeps the mercury from escaping? (There have to be rotating seals with a finite lifetime).
How to grow large crystals under more control: get container for the solution that can be lidded at top. Put saturated solution in with excess crystals on the bottom. Put container in constant-temperature room. Apply slight heat to bottom continuously. Tie seed to fine fish line and suspend in container toward upper part (pass lint through small hole in lid, and close lid). If you get everything right, the initial solution will be a little undersaturated initially, so will dissolve into the seed, removing stray tiny crystals on the seed, but not so much as to dissolve the seed off the line. The temperature gradient causes convection in the solution, the solids at the bottom to dissolve, and the seed to grow. As long as there are solids on the bottom, the growth can continue as long as desired. Growth rate is controlled by amount of bottom heat applied. Saturation can be short-term adjusted by altering total temperature (a slight warming at the start can be used to dissolve into the seed at the start). There is a Scientific American Amateur Scientist article about this, but you will have to order the CD to get this.
Not explained anywhere I can find is a means to get power and signals from the stationary parts to the rotating parts. Is there a slipring or rotary transformer somewhere?
The copper compounds in the newer treated wood corrode "ordinary" galvanized steel screws like crazy! It is best to use stainless steel, or the screws will be gone in a year!Another thing to note, is that the newer "treated" wood (that is arsenic free) is mostly not rated for continuous ground contact. I would use the new "plastic lumber" at the bottom. Even then, termites could build tubes over the base (on the inside of the base, where it can't be seen) and into the floor and walls.
Does anyone have a timing diagram of the signals required? (Otherwise, I am forced to reverse engineer it from the code.) I assume that the signals are of high frequency (in the millions of bits per second), as these ICs demand at least 24 bits per pixel per update. How is this high-speed data stream gotten from the Arduino, which only has a 16MHz clock? Are the core routines written in assembly, or is there some sort of peripheral processing?Regarding the comments about noise concern, keep one thing in mind. Each IC in the chain re-processes and cleans up the signal before sending it to the next IC. So there can be a lot of ground noise in the system, as long as it is not concentrated between 2 adjacently-connected LED ICs. So I would avoid breaking up the power buss as explained in some of the comments. For long busses, put feeders every so often, but do not break up the continuous power rail. Yes, there will be ground loops, but this noise will be distributed, and will not disrupt the signal.
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