So here's a quick little Arduino project which combines an Ethernet shield, a display shield and an Arduino-compatible Adafruit Metro to display the current weather and forecast. The goal of this project was to pull weather data from a remote server (in this case, the DarkSky API) to display the current temperature, weather and a... Continue Reading →
Introduction to Digital Computers: an Update.
So here's where the next video stands. First, as I noted in a previous blog post, I've settled on an 8080-like MPU with 6 8-bit registers and an internal 8-bit bus. Now to make an internal 8-bit bus work, you nee a tri-state gate, a logic circuit which can be used to disconnect our logic... Continue Reading →
Making Circuit Boards.
So one of my goals of my series "Introduction To Digital Computers" is to show the design of a computer that can be built entirely out of NPN transistors. The idea is that by showing the design of a digital computer from the absolute ground up--from something you can hold in your hands rather than... Continue Reading →
A note about the next Introduction To Digital Computers video.
I originally planned to try to get this video out by the end of October. But I just returned from a two week trip to Spain and the south of France--and before I release a video which starts to tie together the registers developed in the third video with the arithmetic logic in the second... Continue Reading →
Introduction to Digital Computers 3: Flip Flops
It's been about a month, and here's the third video explaining how computers work from the ground up. In this third video I discuss flip flops. Starting with two not gates hooked together I discuss how a bi-stable circuit operates, extend this using NOR gates to Set/Reset flip flops, build data flip flops, edge-triggered data... Continue Reading →
Gear Tooth Geometry.
I feel like, with making the first two "Introduction to Digital Computers" videos I've gained a superpower. And I've used that power to help me visualize and solve another problem I was having, figuring out the shape of spur gears (and eventually, internal spur gears, the next major feature I'd like to add to the... Continue Reading →
A second pass at my earth/moon orrery.
I've come to realize making something from scratch winds up building a bunch of prototypes as you both perfect the plans and figure out how to make the parts. And in my case, while the plans may be great--my ability to machine parts is... shall we say questionable? At any rate, I have a second... Continue Reading →
Announcing a new Quick Video: A Full Adder
When we used NPN transistors to build our logic gates, it implies they can be used for building bigger things. In this video I've built a full 1 bit adder from our second Introduction video, entirely from discrete transistors. Build 8 of these--and you have an 8-bit adder. The show notes include the complete circuit... Continue Reading →
Finally, at long last, I got my two 52-tooth gears for my Orrery!
It took another couple of tries, and the trick for these gears was to get the outer diameter to within 0.002". Further, it required depthing the teeth to 1/32" == 0.625" (the precise measurement of the depth of the teeth) rather than cutting them a hair deeper. And I'm suspicious the Sherline divider may not... Continue Reading →