Transformer Inductive Coupling Simulation is SFW

[James] has a friend who teaches at the local community college. When this friend asked him to build a transformer coupling simulation, he was more than happy to oblige. Fortunately for us, he also made a video that explains what is happening while  showing the output on a ‘scope.

For the simulation, [James] built primary and secondary coils using PVC pipe. The primary coil consists of 11 turns of 14AWG stranded wire with 4V running through it applied. The first secondary he demonstrates is similarly built, but has 13 turns. As you’ll see, the first coil induces ~1.5V in the second coil. [James] first couples it with the two windings going the same way, which results in the two 2Mhz waveforms being in phase with each other. When he inserts the secondary the other way, its waveform is out of phase with the primary’s.

His second secondary has the same diameter PVC core, but was wound with ~60 turns of much thinner wire—28AWG bell wire to be exact. This match-up induces 10V on the secondary coil from the 4V he put on the primary. [James]’ demonstration includes a brief Lissajous pattern near the end. If you don’t know enough about those, here’s a good demonstration of the basics coupled with an explanation of the mechanics behind them.

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Homemade Bazooka Has Earned Its Stripes

Many of us dream of launching rockets from our shoulders, but [John] here actually did something about it.

This bazooka build started with a 6″ diameter PVC pipe. He mounted a length of 80/20 T-slotted aluminum extrusion to the pipe through a couple of wood blocks. [John] installed rail buttons on some Estes Alpha rockets which slide along nicely inside the T-slot. He welded a PVC cleanout fitting and plug to one end for easy access and gave her a nice paint job.

The ignition is simple: an irresistible red push button is wired to a 9V battery and a pair of alligator clips. [John] loads up a rocket, puts the gators on the wires of an igniter, pushes said button, and Bob’s your uncle. All he needs now is a pair of gun boats. Video of the build and some demonstrations we don’t necessarily recommend are after the jump.

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Backyard Roller Coaster – Family, Physics and Fun

Coaster Dad Track Segment

This week we have been in touch with [Will Pemble], Geek Dad. After a visit to Magic Mountain in early 2013, his son [Lyle] asked “Why don’t we build our own rollercoaster, Dad?”. [Will] couldn’t think of a single reason why not. This was the start of the CoasterDad Project. Excited by the challenge of building a Backyard Roller Coaster, [Will] also thought it would be a fantastic opportunity to teach [Lyle] about physics. Family, Fun, and Physics – what could be better?

The track is made from parallel PVC pipes on a lumber frame, similar to the one we saw for the Manpowered PVC rollercoaster, but it is more varied and looks a lot sturdier. [Will] is now working on mark II of the cart made from a steel frame with skateboard wheels and has independent axles. He is planning to add a pedal mechanism with freewheel, so you can get a little extra oomph on the rises.

In [Will’s] great videos you can get a front row seat on the coaster and see that even though it is fairly compact it has enough rises, troughs and turns to keep you entertained. It may not be quite as exciting as [Jon Iver’s] homemade rollercoaster, but when finished, the rider will be able go round and round self-propelled to their heart’s content, or till they puke, whichever comes first.  [Will] also explains the theory and practicalities behind making a strong, safe, but really fun coaster. Don’t miss the videos after the fold.

Have you made a backyard roller coaster, or are thinking about building one? Have you got any questions about [Will’s] roller coaster build? He’s up for making a video to answer some of them, so please leave questions for him in the comments below. We will post the video later on.

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Fixing Misaligned PVC With Kerf Bends

misalignment-coupler

Our old pal [Jeremy Cook] is doing his own remix of [Theo Jansen]’s Strandbeest, and like the original, he’s using PVC pipe. Unlike the originals, he’s powering it with motors, not wind, and this has caused a few problems in transmitting mechanical power through a piece of PVC. Nothing is perfect, and in a few points in the legs movement the shaft shakes violently. One motor was lost and another nearly so before [Jeremy] came up with a flex coupler made from PVC.

The technique [Jeremy] is using has seen a lot of use with people building laser cut enclosures. It’s called kerf bending, and it works simply by cutting a few slits in a panel that allow it to bend slightly. This technique was replicated by [Jeremy] on a miter saw, cutting eight slots halfway through a one inch PVC pipe, with each successive cut offset 90 degrees.

The new design works well for transmitting power, and he’s not ruining motors any more. Check out the video below.

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A sublime PVC cannon

PVC

Not to be outdone with hair spray powered PVC cannons, [William] created an even cooler device: a cannon powered by dry ice.

Once dry ice is loaded into the pressure vessel, a burst disk is placed in the breech and the barrel is screwed on. The trigger isn’t very precise – the entire gun is powered by dry ice turning from a solid into a gas – but the resulting cloudy booms more than make up for any imperfections.

Despite building a cannon and using PVC as a pressure vessel, [Bill]’s project is actually quite safe. The ‘trigger’ is a burst valve made out of a disc of aluminum foil held between two sections of PVC. When the pressure rises, the aluminum foil inevitably tears, shooting whatever is in the barrel out and hopefully not into an eye. The ‘safety’ on the gun is a ball valve connected directly to the pressure vessel, and with a pressure gauge and a release valve. We’re more than confident in saying this is pretty darn safe as far as PVC cannons are concerned.

DIY Lighting Solutions

pvc-lights

With daylight savings time starting up, you might not have quite as much need for lighting, but this pair of hacks should keep everything well lit whether outside or indoors.  Check out the videos of both in action after the break.

The first lighting solution comes to us from [Ben]’s Youtube channel. It’s a simple solution, press-fitting a clamp light into a 1 inch PVC Tee to attach the light to a pipe. The base is made with PVC shaped into three feet for a (hopefully) sturdy rest.  Several lights can be used as needed, and would probably work well for making his next video.

The second light also comes to us from Youtube, and is about converting a stock LED light into one that is much brighter. Skip to around 7:00 to see the outdoor comparison.  You may or may not want to do this exact hack, but you never know when you might want to swap out your blinkenlights for something that will scare the neighbors!
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High powered rocket engines made from PVC pipe

rocket

For as much as we enjoy rockets, explosives, and other dangerous things, we haven’t said a word about the works of [Richard Nakka]. He’s the original hacker rocketeer with thousands of words dedicated to the craft of making things move straight up really fast. One of his more interesting builds is his series on building rocket engines out of PVC pipe written in conjunction with [Chuck Knight].

For the propellent grains, the PVC rocket didn’t use the usual potassium nitrate and sugar mixture of so many homebrew solid rockets. Instead, it uses Sorbitol, an artificial sweetener. While melting and casting the Sorbitol-based propellant grains is much easier than a sugar-based concoction,  the Sorbitol had much less thrust than a typical sugar rocket, making it the perfect candidate for a PVC engine.

For those of you wondering about the strength of a PVC engine casing, [Richard] does say making larger rocket engines out of 2 or 3-inch PVC may not make much sense due to the increased chamber pressures. There is a fairly clever reinforcement method for these PVC rockets (PDF warning) that involves using PVC couplers, but the experiments into the strength of these casings have yet to undertaken.

Thanks [Caley] for sending this one in.