Ground loop in a lab power supply

Today, I decided to finally plug in my instruments properly, and plugged both my cheap lab PSU (ARKSEN 303D) and oscilloscope into sockets on the same strip with real ground prongs. After connecting the scope ground with the PSU negative rail, it quickly became clear that something’s wrong, because the wire connecting them went white-hot and sort of caught fire.

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50W LC resonant converter, power board V1

In this note I will describe a part of a 50W resonant LC converter that I am designing. The converter will be modular: it will feature a control board with an Ethernet interface, a frontend board with a rectifier/multiplier and a matching network to allow current/voltage readouts, and a power board with the high-voltage transformer, its driver and signal isolation.

This note describes the first revision of the power board.

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Measuring diode recovery time

After assembling a full-wave rectifier out of some 1A7 1kV-rated diodes, I noticed that it does not, in fact, rectify. I speculated that the diodes I used have a recovery time too high. Since it was not specified in the datasheet, I decided to measure it myself, which I describe in this note.

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CNC-milling glass

In an earlier note I described an improvised vacuum chamber. I wanted to perform sputtering in it, but an acrylic flange would melt if the feedthroughs got hot enough (and they will get hot), and that would be pretty gross.

In this note I describe how I CNC-milled a glass flange.

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An improvised vacuum chamber

In this note I describe an improvised vacuum chamber made out of stuff I had laying around the house, and some fun things I did with it.

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MOSFET-based Gouriet-Clapp capacitive three-point oscillator

In this note I describe a Gouriet-Clapp capacitive three-point oscillator, which is an extremely simple circuit that produces high-frequency (~20-30MHz) electromagnetic field. It can light up gas discharge tubes and as such can be used to estimate pressure in vacuum systems.

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Photographing PCD8544

I had a broken Nokia 3310 LCD on my hands, so I decided to take a photomicrograph of the display controller, PCD8544. As far as I’m aware this is the first publicly accessible die shot.

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Closeup of a broken LCD

I broke a Nokia 3310 display, and in a closeup, both pixels and what appears to be segment electrodes at the border, are distinctive.

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Compactly organizing an E12 resistor set

In this note I describe a simple and convenient arrangement of an E12 resistor set that, crucially, takes very little space.

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A fixture attachment system for CNC3020T

I found it convenient to have a table with a grid of nuts for attaching the workpieces, that could double as victim material. In this note I describe how to make such a table out of HDPE.

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