One of the current projects I’m tinkering with is an 8-bit computer. It’s something I’ve wanted to build for several years, and now that I’ve finished so many other projects, I finally have the bandwidth to take this on. I’m aware that Ben Eater has done this, and I’m not intending to compete with his …
Prior to the digital revolution, analog electrical computers were used to solve complicated mathematical equations (missile guiding, aerodynamics, stability, etc.). Many systems that can be modeled as a set of equations (linear, non-linear, differential, ordinary, partial, etc.) can be built as an electrical analog. Put very simply: If you can create a circuit that models …
Any synchronous sequential digital logic circuit requires a clock source (a square wave oscillating between logic LOW and HIGH values) for the circuit to function. Typically, a clock frequency is determined by the circuit designer (taking into account speed requirements as well as any limitations from the circuit components themselves). Once that frequency is known, …
Apparently, people actually read this blog (who knew!), so why not write about a topic I find interesting: multiplication. Multiplying two values together (as opposed to multiplying one value with a constant) is actually a difficult computational task. This was difficult to do in mechanical analog computers (shout out to any potential future mechanical engineers …
Keeping a record of the projects that you build is more important than you may think. Even if you have really well-commented code saved somewhere, or a schematic, it’s still really helpful to keep notes in a project notebook. Each of my projects gets written up in my notebook, which is open on my table …
When designing a sequential circuit with one or more clock signals, particularly circuits with either high-frequency clock signals, lots of wires, or both, noise can be a big problem! The circuit below from a past Digital Systems Design Project Showcase shows a good example of a circuit with lots of unwanted inductance caused by many …
Sometimes a 555 timer does not output a great square wave from 0-5 V. In this case, when using it as a clock source for a flip-flop, a bad 555 timer output can lead to missed clock pulses and seemingly strange behavior on the output. To correct this, use one or two Schmitt inverters (7414) …
In digital systems, I teach about a bunch of different hardware solutions that can be used to implement a project. I thought it would be fun (and not to mention, a learning experience for me) to come up with both a combinational logic project and a sequential logic project and implement each one using a …
The purpose of this post is to make the design process of creating printed circuit boards (PCBs) a little less scary. Please note that, as with most of the hobby stuff on my website, I am self taught. This means that I use auto-routing, don’t worry about ground planes, and the most difficult thing I …
Frequently, I will come up with an idea for a project I’d like to do. Some of the projects are small in scope, like designing a PCB for some DIP components so that my students don’t have to spend time wiring up a frequently-used component (like the 7447 and a 7-segment display). Those are relatively …