So I decided that I’d like to add a real-time clock (RTC) to the Zolatron project because … why not? Should be easy, I thought. Lots of people have done it. All I need is the right chip. Maybe that’s where I made my mistake. As it turned out, for some reason, I already own three copies of the Microchip… Read more »
When you’re dealing with computer logic, things can get very complicated very fast. This is especially true when it comes to address decoding. You can easily find yourself tangled in a messy web of AND, OR, NAND and NOR gates. And there’s a problem you can run into when stringing together a bunch of logic gates – propagation delay. It… Read more »
It was about to go in the recycling pile when I thought, “I wonder if I can save it.” There’s no telling how old this lovely Casio fx-590 calculator is, because in spite of deploying my best Google-fu I can find very little information on it. One source suggested that maybe it came out at the beginning of the 1990s…. Read more »
If there’s one sound that makes me nostalgic, it’s the brrrrr-BIP! noise of a BBC Micro being switched on. And that sound – as well as pretty much all the Beeb’s audio capabilities – can be traced to one chip – the Texas Instruments SN76489. This chip was used in a whole host of devices, including Sega consoles and arcade… Read more »
One of the tools I knew I was going to want straight away on my new LattePanda Alpha is Sigrok – or to be more precise, the PulseView logic analyser tool. I already have this running on my old Windows 7 laptop, but who the hell wants to use that, right? However, Sigrok is created by hackers for hackers and… Read more »
While idly mulling over how one might create a control panel for an eight-bit microcomputer – something I plan to do for my (very) slowly progressing Zolatron 64 project – it occurred to me that there might be occasions when it would be useful to send a brief pulse. I didn’t have a specific use case in mind. In fact,… Read more »
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 »
Over the past three posts I’ve looked at three ways of soldering SMD/SMT components on to a PCB – by hand, reflow soldering with a hot air gun, and reflow soldering with an oven. Now it’s time to draw some conclusions.
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 »
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 »
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 »
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 »
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 »
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 »
[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 »