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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What is Kemet doing in this circuit?

What is Kemet doing in this circuit?

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

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

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

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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Mr Kurt inspires a circuit

Mr Kurt inspires a circuit

The wise Mr Kurt*, sometime correspondent of this blog, has been helping someone out with a design. It is not for me to reveal his intellectual property, but the circuit neatly uses the fewest number of components to get the job done with the voltage available. In a round-the…

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RFID is not only magnetic

RFID is not only magnetic

I have found yet another gap in my knowedge (only the 2nd today though) -  I have only been thinking of inductive RFID whch I think battery-free. Meanwhile, electromagnetic battery-free RFID has popped up – there is a mini-backgrounder on this page from Sky RFID. Actually, I do temember…

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Phase-locked loop triumph

Phase-locked loop triumph

I have always had a soft spot for phase-locked loops – at least, I have since I first found out what they were. What I like about them is that they servo into the best answer for a given situation – For example, they can get in there and dig a…

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