engineer-in-wonderland

Rooting around in the fascinating stuff at the bottom of a draw labelled 'Engineering - Junk Miscellaneous'. Delving amongst the delightful...

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Fridge freezer conundrum

I am likely to by a fridge/freezer in the near future.

And, reading around, I discovered that fridge/freezers with poor thermostats get colder inside when the weather is warmer, and warmer inside when the weather is cooler.

Can this be true?

How, and why not get colder inside…

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How do you design a dust sensor

I have just had a ‘why didn’t I think of that’ moment.

Samsung’s VC21F50UKGC vacuum cleaner has a dust detector that indicates if there is much dust going up the pipe – to alert the user they are over a particularly dusty bit.

What an nice idea, and..

.. I…

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Book: Graphics touch sound and USB on PICs

I have not read this book, but a friend of Electronics Weekly said the author is a nice guy.

It is called ‘Graphics, Touch, Sound and USB: User Interface Design for Embedded Applications’, and uses practical examples.

So, if you want to know about interfacing complex perpherals to microcontrollers, this…

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Wearable devices can reveal more than you think

Cyber security firm Symantec has demonstrated people can be traced by their wearable fitness devices – wristbands, smartwatches and phones – and could be revealing far more than they ever imagined.

The vulnerability is through Bluetooth Smart (was Bluetooth Low Energy).

Many of these things transmit an ID number over and over…

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What is Kemet doing in this circuit? Kemit tells all.

Kemet has a supercapacitor balancing development kit.

Supercapacitors are fascinating things and are getting better and better all the time.

They need balancing when charged in series to prevent differing capacitances causing full capacitors to over-volt while other are still filling.

This kind of capacitor has some ionic stuff…

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Fun in a box

I am not normally one for gadgets, but an amazing little quadcopter has both put a smile on my face and sent me nuts over the past few days.

For a couple of months before GCSE time, I was helping with revision.

This was a pleasure and, I think I…

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Zeta: Yet another dc-dc topology

Call me slow, but I only just discovered the zeta dc-dc power converter topology.

It is a bit like sepic and Cuk, in that the output can be higher or lower than the input.

And that there are two inductors and a series capacitor.

And it is a bit…

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Base emitter ‘Zeners’ don’t have to be 7V

A rule of thumb is that the reverse breakdown voltage of bipolar transistor base-emitter junctions is around 7V.

Wnich is why the transistors in this active bridge rectifier are ‘back-to-front’.

But this does not have to be the case.

For example, the 2SD2704K from Rohm, a transistor…

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More on: low saturation matrix transistors

Much as I have been banging on about low-saturation transistors from Diodes (was Zetex), I have omitted to mention that NXP makes then too.

Here is NXP’s low-saturation matrix transistor backgrounder…

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