Op Amps Before Transistors: A 600V Vacuum Tube Monster

August 9, 2018 by Ben James 11 Comments

Op amps. Often the first thing that many learn about when beginning the journey into analog electronics, they’re used in countless ways in an overwhelmingly large array of circuits. When we think about op amps, images of DIPs and SOICs spring to mind, with an incredibly tiny price tag to boot. We take their abundance and convenience for granted nowadays, but they weren’t always so easy to come by.

[Mr Carlson] serves up another vintage offering, this time in the form of a tube op amp. The K2-W model he acquired enjoyed popularity when it was released as one of the first modular general purpose amplifiers, due to its ‘compact form’ and ‘low price’. It also came with large application manuals which helped it to gain users.

In order to power up the op amp and check its functionality, +300V and -300V supplies are needed. [Mr Carlson] is able to cobble something together, since it’s very apparent that he has an enviable stash of gear lying around. A 600V rail to rail supply is not something to be taken lightly, though it does give this particular model the ability to output 100V pk-pk without any distortion.

The op amp is set up as an inverting amplifier, and once powered on proves to work flawlessly. As always, the video is an entertaining watch, stuffed full of retro electronics trivia. We’re big fans of [Mr Carlson]’s work, and have previously written about his adventures with a colossal walk-in AM radio transmitter, as well as his restoration of a 1930s oscilloscope and subsequent transformer de-potting.

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Hair-Raising Tales Of Electrostatic Generators

June 13, 2018 by Al Williams 17 Comments

We tend to think of electricity as part of the modern world. However, Thales of Mietus recorded information about static electricity around 585 BC. This Greek philosopher found that rubbing amber with fur would cause the amber to attract lightweight objects like feathers. Interestingly enough, a few hundred years later, the aeolipile — a crude steam engine sometimes called Hero’s engine — appeared. If the ancients had put the two ideas together, they could have invented the topic of this post: electrostatic generators. As far as we know, they didn’t.

It would be 1663 before Otto von Guericke experimented with a sulfur globe rubbed by hand. This led to Isaac Newton suggesting glass globes and a host of other improvements from other contributors ranging from a woolen pad to a collector electrode. By 1746, William Watson had a machine consisting of multiple glass globes, a sword, and a gun barrel. Continue reading “Hair-Raising Tales Of Electrostatic Generators” →

Lightning Generator From Electric Lighter

June 5, 2018 by Bryan Cockfield 16 Comments

Generating high voltages isn’t too hard. A decent transformer will easily get you into the 100s of kilovolts, provided you’re a power company and have access to millions of dollars and a substation to put it. If you want to go above that then things start getting difficult, and most tend to look in other places for high voltages such as voltage multipliers.

These devices use nothing but capacitors and diodes, as [Jay] from [Plasma Channel] shows us how to build a small desktop version of a voltage multiplier that can produce almost 70 kV. That’s enough to throw a substantial spark, powered by nothing but a rechargable battery found in an electric lighter. They can also be cheaper than transformers to a point, since they require less insulation and less copper and iron. The voltage multiplier works in stages, with each stage boosting the voltage to a critical level above the stage before it similar to a Marx generator.

Similar designs are used by laboratories to simulate lightning strikes, and can generate millions of volts. They’re a cost-effective way of generating huge voltage pulses and studying everything from the effects of lightning on various equipment to generating X-rays in fusion power tests. We’ve even seen them in use in lasers.

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A Vacuum Tube And Barbecue Lighter X-Ray Generator

May 12, 2018 by Dan Maloney 55 Comments

A certain subset of readers will remember a time when common knowledge held that sitting too close to the TV put you in mortal peril. We were warned to stay at least six feet back to avoid the X-rays supposedly pouring forth from the screen. Nobody but our moms believed it, so there we sat, transfixed and mere inches from the Radiation King, working on our tans as we caught up on the latest cartoons. We all grew up mostly OK, so it must have been a hoax.

Or was it? It turns out that getting X-rays from vacuum tubes is possible, at least if this barbecue lighter turned X-ray machine is legit. [GH] built it after playing with some 6J1 rectifier tubes and a 20-kV power supply yanked from an old TV, specifically to generate X-rays. It turned out that applying current between the filament and the plate made a Geiger counter click, so to simplify the build, the big power supply was replaced with the piezoelectric guts from a lighter. That worked too, but not for long — the tube was acting as a capacitor, storing up charge each time the trigger on the lighter was pulled, eventually discharging through and destroying the crystal. A high-voltage diode from a microwave oven in series with the crystal as a snubber fixed the problem, and now X-rays are as easy as lighting a grill.

We have to say we’re a wee bit skeptical here, and would love to see a video of a test. But the principle is sound, and if it works it’d be a great way to test all those homebrew Geiger counters we’ve featured, like this tiny battery-powered one, or this one based on the venerable 555 timer chip.

Neon Lamps Light Up Dim Ion Motor

April 14, 2018 by Steven Dufresne 6 Comments

Small pinwheel type ion motors fall into the category of a fun science experiment or something neat to do with high voltage, but Hackaday’s own [Manuel Rodriguez-Achach] added a neat twist that incorporates neon lamps.

Normally you’d take a straight wire and make 90 degree bends at either end but pointing in opposite directions, balance it on a pole, and apply a high voltage with a moderate amount of current. The wire starts spinning around at the top of the pole, provided the ends of the wire are sharp enough or the wire has a small enough diameter. If your power supply has ample current available then in the dark you’ll even see a purplish glow, called a corona, at the tips of the wire.

[Manuel] made just such an ion motor but his power supply didn’t have the necessary current to produce a strong enough corona to be visible to his camera. So he very cleverly soldered neon lamps on the two ends of the wires. One leg of each lamp goes to the wire and the other end of the lamp acts as the sharp point left out in the air for emitting the ions.

The voltage needed across each lamp in order to ignite it is that between the high voltage power supply’s output and the potential of the surrounding air. That air may be initially at ground potential but he also bends the other output terminal of the power supply such that its tip is also up in the air. This way it sprays ions of the opposite polarity into the surrounding air.

Either way, the neon lamps light up and the wire spins around on the pole. Now, even without a visible corona, his ion motor makes an awesome display. Check it out in the video below.

For more about these ion motors, sometimes called electric whirls, check our article about all sorts of interesting non-electromagnetic motors.

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Practical Plasma For Thin-Film Deposition

April 11, 2018 by Dan Maloney 32 Comments

[Nixie] wants to sputter. We know, who doesn’t? But [Nixie] has a specific purpose for his sputtering: thin-film deposition, presumably in support of awesome science. But getting to that point requires a set of tools that aren’t exactly off-the-shelf items, so he’s building out a DIY sputtering rig on the cheap.

If you’re not familiar with sputtering, that’s understandable. In this context, sputtering is a process that transfers particles from one solid to another by bombarding the first solid with some sort of energetic particles, usually electrons or a plasma. When properly controlled, sputtering has applications from mass spectrometry to the semiconductor industry, where it’s used to either deposit thin films on silicon wafers or etch them away selectively.

No matter the application, sputtering needs a stable stream of plasma. [Nixie] has posted a series of articles on his blog walking us through his plasma experiments, from pulling a really strong vacuum to building a high-voltage power supply from a microwave oven transformer. It’s a project that needs a deep well of skills and tools, like glassworking, machining, and high-voltage electronics. Check out the plasma in the video below.

Will [Nixie] be using this for a DIY fab lab? Will it be used to make homebrew LEDs? The world waits to hear.

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Building A Static Grass Applicator

March 21, 2018 by Tom Nardi 16 Comments

A “Static Grass Applicator” is very specialized tool used by model makers to create realistic grass. Don’t feel bad if you didn’t know that, neither did we. Anyway, the idea is that you distribute a fine filament over the surface, and then use static electricity to make the “blades” of grass stand up vertically. This is a huge improvement over the old school method of manually placing the grass on the model, but the tool itself is somewhat expensive, at least for a decent one.

But thanks to avid modeler [Luke Towan], those looking to up their diorama game without breaking the bank now have a fantastically detailed guide on building their own grass applicator that is not only fairly cheap (as little as $20 USD depending on what your part bins look like), but is robust enough to last for years of service.

The heart of the device, and probably the only part you’d need to go out and buy especially for this project, is a small 12V negative ion generator. This is used to setup an electric charge between the grid of the applicator and a long wire that gets attached to the piece you’re working on. What little wiring there is simply provides a switch and some status LEDs. The design [Luke] has come up with lets the user switch between and internal 9V battery for portability, or an external 12V wall adapter for larger projects.

Building the chamber to hold the grass filament as well as the handle which houses the electronics will take longer than anything else, and even that seems pretty straightforward. Given the impressive results shown in the video after the break, it’s actually pretty surprising how simple the device is.

The setup used here reminds us of the DIY powder coating we covered a few years back.

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