Category Archives: Electronics

SMD soldering coda: KiCad, PCBs and pad sizes

In many ways this is Part 5 of my four-part series on SMD soldering because it addresses problems I had with reflow soldering and TSSOP ICs. I used two TSSOP chips – the TXB0104 and TXB0108 level shifters. Both have pin sizes of 0.3mm and a pin pitch – the distance from the centre of one pin to the centre… Read more »

Adventures in SMD soldering – part 3: in the oven

If you’re working with solder paste, as I was in the last post, there’s an easier method of applying heat than blasting the PCB with a hot air gun. And that’s to put it in the oven. This is how most commercial soldering is done these days. But this reflow soldering is easy to do at a hobby level, too…. Read more »

Adventures in SMD soldering – part 2: hot air

While hand soldering SMD/SMT components on to a PCB is certainly feasible, I figured there had to be a better way. That’s when I heard about using hot air rework stations to do the job. The concept is simple: apply solder paste to the pads; place the components on the paste; apply hot air. The paste melts and effectively sucks… Read more »

Adventures in SMD soldering – part 1: by hand

A little while back, I wrote about my SMD soldering setup. It was very much an overview and mostly about the kit. Now, I know many beginners, like me, are intimidated by soldering surface-mount parts. They’re so small and the pins on ICs are so close together. But there are good reasons for getting over the fear. Many parts are… Read more »

SMD soldering setup – just add air

It was time to get serious about SMD soldering. And I have to say, I’m really pleased how well this has worked out so far. Now that I’m getting into, and hugely enjoying, PCB design and getting boards fabbed, I can’t escape tackling SMD (or SMT if you prefer) components. And this is a good thing. For a start, an… Read more »

Debouncing fun with Schmitt triggers and capacitors

You simply can’t trust switches. You think they’re either on or off, but the truth is that, in getting from one state to the other, they can change their mind many times. This is a phenomenon known as switch bounce and it happens because switches aren’t perfect. Just at the point where they are making or breaking contact, certain mechanical… Read more »

Epson MX-80 Part 4 – ESR check of the dodgy caps

It seems strange that both the capacitors and the transformer – the chief suspects in the investigation as to why my Epson MX-80 F/T III dot matrix printer belched out smoke – tested fine with a multimeter. As far as the capacitors were concerned, I measured resistance directly across their leads (having removed them from the circuit board) looking for… Read more »

PCB design: first steps with KiCad

[Eagle vs KiCad part 5] Having got as far as a complete schematic for my HexMonitor project with Eagle, it’s time to try the same thing with KiCad. And just as I did with Eagle, my plan is to design my HexMonitor project that takes signals from one eight-bit and one 16-bit bus and display their values on a four-digit, seven-segment… Read more »

The stuff I use

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It’s always fascinating to know what kit others use. Reviews are all very well, but I’m more interested in what people work with on a day-to-day basis. So I’ve set up an account over on kit.com. I’ll be sharing lists of the equipment I actually use and like. If you see something in these lists you’ll know that: I bought… Read more »

Hacking a film scanner

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I’m building a rig to digitise my large selection of 35mm transparencies and negatives and in the process I’ve encountered what could be one of the worst electronic products I’ve ever bought. And in the spirit of the ineffable Big Clive, I thought I’d share my adventures in taking it apart. In some ways this belongs over on my photography… Read more »

PCB design: connecting with Eagle

[Eagle vs KiCad part 4] In the last post in my Eagle vs KiCad series I’d got as far as using Eagle to place all the components for the HexMonitor project in a schematic. Now it’s time to join them together. Even before I begin, something tells me that perhaps this is too ambitious a project for my very first PCB…. Read more »

The perils of antistatic foam

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Not all foam is created equal. Let me explain. When you buy integrated circuits (ICs, or chips, if you prefer) they’ll sometimes be delivered with their cute little legs stuffed into black foam. That’s because many chips, and particularly CMOS-based ones, are rather sensitive to static electricity. If a static potential builds up between the legs (and if, like me,… Read more »

PCB design: modifying a part with Eagle

[Eagle vs KiCad part 3] In the last post, I’d got as far as putting all the parts for my HexMonitor project into the schematic, albeit without actually connecting them. There was a good reason for that: while I (somewhat surprisingly) found the connector part I needed in Eagle’s default libraries, it wasn’t labelled the way I wanted. This was… Read more »