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Logic Gates Demonstration Kit

When teaching a Math Circle, I was discussing with the students various logic operations and logic gates. We went from basic AND and OR gates to constructing flip-flop circuit and full adder - using software simulation. I wanted to show them real electronics gates, so I started looking for a demonstration kit which would be

functional: enough pieces to build something interesting such as flip-flop or adder
easy to use
clean-looking - breadboard with a rat’s nest of wires doesn’t make a good demonstration kit
large enough so that it can be shown to a group of several students
not too expensive: under $50 for the whole kit
I couldn’t find such a kit; the closest I found was this one from Sparkfun, but is still fails on several counts. So I decided to make my own, which meets all the requirements above and more. Here are some features of my kit:

It uses custom black PCBs; to make it look nicer, I used surface-mounted components placing most components on the back
contains 5 types of gates (AND, OR, XOR, NAND, NOT) plus a separate 3-bit input board
is powered through USB-C connector
each board is relatively large - 48x72mm - only slightly smaller than a credit card, with high contrast white on black marking and bright blue LED to indicate states
boards are connected by a common 3-wire connectors, commonly used for servos and widely available
boards have stick-on magnets on the back, allowing one to place them on a magnetic whiteboard or blackboard or any other magnetic surface - even refrigerator door!
Using surface mounted components makes it more difficult to solder, but in this case, the components are few and not too small, so this makes a nice first SMD soldering kit for those wishing to learn SMD soldering. Unlike many other kits, it also serves a useful purpose!

Full list of necessary pars is listed in Step 1 below. With delivery to US, it will cost you about $90, but will give you enough materials for 10 gates of each kind. If we take the basic kit to have 2 boards of each kind, plus one 3-bit input, you will have enough for 5 kits.

You will also need a decent soldering iron, a hot air reflow station (basically, temperature controlled heatgun), solder paste (I used this low-temperature one), tweezers, flush cutters and other basic tools.”

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