Educational Logic Gate Board

This is a board I based roughly on a setup we had in high school, that I was taught logic gates with, once upon a time.

I designed the layout about two years ago using Robot Room Copper Connection. Unfortunately, the software has been bought out since, and a full version is no longer available for purchase. (The “new” versions are vendor-locked.)

Recently I ordered some PCB prints along with the prints for another project, and last week I finally put everything together.

The CD4572 chip on the board provides an AND, an OR, and 4 NOT gates. Two of the NOT gates are pre-wired to the AND and OR to get a NAND and NOR, for convenience.

Using this layout, you can teach the basics of logic gates. An AND gate can be constructed using the OR and NOT gates, and an OR gate can be constructed similarly. Once a student is familiar with the logic, they can advance to creating a basic latch (tap a button, and a light stays on), followed by a set-reset latch.

A student can then advance step-by-step to more complex concepts by using subsequent boards which directly provide a set of latches to create a counter. Eventually, learning enough components to build a basic calculator, and moving onto directly using ICs or hardware synthesis languages.

For safety (baby proofing), to avoid shorts, the design puts a resistor in all the wires. (Back in high school, the batteries of the educational boards went bad at suspiciously fast rates.) Output sockets still need to have a diode added in the next revision, since the output status LEDs currently give misleading output when you wire outputs together.

The power supply was constructed from leftover boards of an older revision of another previous project, reusing a portion of the 7805 circuit.

In a next revision, aside from the extra safety diodes on the outputs, adding some convenient buttons to the inputs might be helpful in further lowering the learning curve. A proper solution for the power supply should also be thought of. Additionally, adding some holes in the logic board design for more properly soldering a hard wired supply..