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Engineer In Wonderland

Sealing nylon 3D prints

Laser sintered nylon 3D prints are porous – with a surface like Trebor mints according to 3Dprint-UK, unless they get treated in some way. Sealing the material, which seems to be it is PA2200, to stop it getting grubby or leaking water into one-off enclosures is not an exact science. 3D print firm Shapeways has a blog with a link ...

SEPIC vs fly-back

Just found an interesting article comparing fly-back and SEPIC power supply topologies getting a particular job done – a dc-dc converter for cars. It is excellent, because both the supplies were built and tested. Even more excellent, if is from an Electronics Weekly article, written by a couple of TI guys, whe really know what they are taking about. Read ...

De-magnetising conundrum

I have googled this without finding a satisfactory answer. How long does it take a well-magnetised Alnico magnet to loose magnetism once its keeper/armature is removed? The question arose from a discussion the wise Steve Kurt about removing the armatures from old permanent magnet generators – specifically old Sturmey Archer Dynao Hubs. I vaguely remembered something about the magnet’s own ...

Perovskite: not always solar, sometimes heatsink interface

Perovkite materials are getting a name for themselves in the world of solar cells, and now Imperial College has used the same crystal structure to make a material that predictably and tune-ably shrinks as it gets warmer – as opposed to the normal action of expanding when heated. “Electronic components often expand at different rates when heated. This can cause ...

In praise of Peak Electronic Design

Peak Electronic Design LCR45

I needed to measure an inductor today, and got out my trusty Peak Atlas LCR40. This is a terrific little LCR meter, built around a PIC microcontroller, and made in Derbyshire by Peak Electronic Design. I had a look on the company website, and it has even more models of meter than it used to have – all in the ...

Zeta – that other dc-dc topology

Zeta dc-dc TI

Zeta, or ‘inverse sepic’, is another one of those dc-dc converters, like Cuk and Sepic, that have a capacitor in series with the power path. Both zeta and Sepic have the same transfer function: Vout=Vin x D/(1-D). BTW, this is also the boost converter equation. Cuk is the same, except the output is inverted. input current output current zeta pulsed ...

Sony patents camera contact lens, but….

Sony has applied for a patent** for a contact lens with a built-in camera and display. But, unless I am reading it wrong, in which case I am really sorry, it reads like a boy saying “if I had a staircase a million million miles high I would walk to the moon. I would take sandwiches, and Toby, and a ...

Fewer pies for antique lamp post?

Unusual lamp post

I came across this in my travels, a delightful and mysterious lamp post. My guess is that is has/had a transformer in the bottom, but I have no real idea. Maybe it was an electricity sub-station, with added lamps. It has a plaque on it. Anyone know why it is like it is?

Mystery box appears

Mystery box

One of these has just been put up in the local vineyard. Failing to measure it at the time, I am guessing it is on a 100mm wide pole, so it is about 300mm across. The pole is about 3m high. My best guess is bat roost? But the pole is awfully springy and the thing will get direct sunlight, ...