I’ve recently become interested in Nixie tubes. Nixie tubes are neon filled glass tubes that contain cathodes in various shapes, numbers being the most common, and a mesh anode. Passing a current through the cathode causes the neon gas to ionize which makes it light up.
The problem with these tubes is that they voltages of around 170V in order to ionize the gas. Fortunately, most tubes only need a few mA which makes the supply design simpler and easy to run off a wall wart.
A low cost Nixie Tube Power Supply - [Link]
Dual-Resonant Solid State Tesla Coil (DRSSTC). Shane writes – [via]
It’s been a long time since I built something that isn’t a robot, a motor controller, anelectric vehicle, or a multirotor. Also, the Edgerton Center Summer Engineering Workshop (responsible for the DIY Segway, BWD Scooter, Cap Kart, and tinyKart) isn’t running this year, so I feel the need to take on a summer project of my own. Inspired by the work of MITERS regulars Tyler, Daniel, Bayley, and Ggy, I’m attempting to build..
Specifically, I’m building a Dual-Resonant Solid State Tesla Coil (DRSSTC). Tesla coils generate high voltage and pretty sparks using electromagnetic induction. They’re loosely-coupled air-core transformers where the world is your output load. (Or just the toroidal “top load” and the air around the Tesla coil.) “Dual-resonant” implies that both the primary and the secondary form RLC series resonant circuits, tuned to about the same natural frequency. “Solid state” implies that the primary circuit is driven (near resonant frequency) by transistors, usually IGBTs although I will be starting with MOSFETs.
Building a Dual-Resonant Solid State Tesla Coil (DRSSTC) - [Link]
Over the past few years, I’ve built up a few battery packs for myself and for other people. Most of them worked fine – in fact, one of the first packs I built over five years ago is still in service, working fine in a torch in the bottom of my cupboard.
The big problem with soldering to batteries is that you tend to damage the plastic separator, and the cell seals. This – as you might guess – is not a Good Thing™. In some cases, solder can splatter over the cell’s pressure relief vent. There’s a reason the datasheets make a big fuss about the vent – in an overpressure situation, the vent is used to release the excess pressure in the cell. Needless to say, blocking the vent with solder is never a good plan, unless you’re trying to get a Darwin Award, or you happen to enjoy watching your battery pack undergoing rapid, uncontrolled self-disassembly.
In industry, resistance welding is used instead of soldering. Not only are the welded joints smaller than solder blobs, but they cause less damage to the cell. The only problem is the cost of resistance welding equipment. A low-end resistance welding machine can cost upwards of GB 2,000.
The Poor Man’s Battery Tab Welder - [Link]
Radu Motisan writes:
Here is an electric fence, perimeter protection circuit, designed to run on batteries, and provide configurable pulses of up to 20KV, to protect a tent perimeter against bears or other animals, out in the wild.
The high voltage generated is not dangerous because of the low current (and power), but it will produce intense pain.
Electric Fence – 20KV pulses for perimeter defense - [Link]
I found some old pictures of me playing around with a flyback, and I wanted to test out this awesome gallery thing I found, so I mushed them together, and well, here they are!
High-voltage arcs using a flyback transformer from a monitor - [Link]
Matt Renaud writes:
It’s time for a little confession: I don’t always spend as much time on my power supply designs as I should. Sometimes I get excited about my latest circuit and after looking for just the right tubes, output transformers, coupling caps, and low noise resistors, the power supply design becomes almost an after thought. Sometimes things turn out ok and there are no problems. Other times I end up with bad voltages, unacceptable power supply sag, channel crosstalk, or worst of all, a hum that I just can’t seem to eliminate. It’s at these times that I always wish I had taken a little more time to get it right.
The truth is, there is no reason to suffer power supply set backs like this. The design of basic tube power supplies is actually very straight forward. And, if we rely on the excellent work of those who’ve come before us (O. H. Schade, N. H. Roberts, D. L Waidelich, H. J. Reich), we don’t even need to tackle any advanced math or taxing mental gyrations to arrive at some truly excellent power supply designs.
Power Supply Design for Vacuum Tube Amplifiers - [Link]
Luca is building a Nixie clock, and in this post he covers the high voltage power supply section.
Nixie tubes are digit displays that use ~170V between the digit wire and a wire mash, to agitate the gas inside the tube. This surrounds the digit wire with a orange glow and it becomes visible through the tube.
Luca is using the MAX1771 based DC/DC boost converter to supply the high voltage required. This DC/DC steps up the 9-12V input to 180V output, as a bonus it has an additional 5V output for the rest of the circuit board.
Nixie clock HV power supply - [Link]
Powering the Imaging on IMAGE – [via]
The IMAGE spacecraft was launched from Vandenberg AFB in 2000 to study the aurora borealis or “Northern Lights”. IMAGE was the first satellite mission dedicated to imaging the Earth’s magnetosphere, the region of space controlled by the Earth’s magnetic field and containing extremely tenuous plasmas of both solar and terrestrial origin. IMAGE is an acronym for Imager for Magnetopause-to-Aurora Global Exploration.
This is the high voltage power converter module for the Far-Ultraviolet (FUV) imaging instrument in the IMAGE satellite. It converts 28V to 5000V DC for the Wideband Imaging Camera (WIC). The WIC images the whole Earth and the auroral oval from satellite distances greater than 4 Earth radii to the center of the Earth. It selects the spectral range between 140 nm and 160 nm in the ultraviolet part of the optical spectrum.
Here is a good intro video on the science, and subsequent satellite missions: “What triggers the sudden, magnificent movements of the aurorae that appear around the far poles of the earth? It’s been a nagging question of space science for decades.”
Thinking outside the planar - [Link]
Flyback transformers are found in monitors, TVs or anything with a CRT, and are sometimes known as Line OutPut Transformers, or just LOPT. They are used for generating high voltage for the CRT, which is needed to create an electric field, which in turn accelerates electrons towards the screen, which finally excite phosphors and create the image you see. Flybacks are designed to work best anywhere between 15 to 150 kHz, so some experimentation is required to find the intended operating frequency. TV flybacks are generally designed for upper audio frequencies, which is the cause of the high pitched noise heard from a muted TV.
Flyback Transformer Drivers - [Link]