Computer Logic Lab

The Computer Logic Lab is a World of Discovery series educational kit manufactured in Taiwan by the UK based Humbrol Company in approximately 1985. There was also an identical version manufactured by the Natural Science Industries (NSI) Ltd in US. It has 60 experiments and is for children age 12 and over. It is ideal for those students who wish to learn about digital gates, and in particular, NAND gates used in digital electronics. The main and only chip is the 7400, which consists of quadruple 2-input positive-NAND gates, and majority of the project circuits in the manual use this IC.

This lab caters for a very wide range of ages, because it starts with very simple experiments covering the basic principles that a 12-year-old could understand. Some of the easier circuits consist of a switch, resistor, and an LED. However, it progresses through to complicated circuits such as a gated flip-flop, half adder, and frequency divider. Therefore, this would be interesting to a GCSE level student as well. Overall, this lab provides a good understanding of the NAND gate function and the different circuits you can make from it.

A quad NAND IC such as the 7400 is extremely cheap and versatile, and college students capable of using a soldering iron, may even make permanent circuits. The IC costs only a few pence and it is remarkable how useful it can be. It is easy to damage this IC; however, it is equally easy to replace it. In this multi-page article, you can see how to repair a damaged lab.

7400 IC

Electrolytic Capacitors

LED and Series Resistor

Switches

Resistors

Cost / eBay

This is a product from 1985, and therefore vintage. It was mass-produced, however, due to the plastic and cardboard construction; many would have ended up in landfill when the 7400 IC broke. However, this article shows how easy it is to replace this IC, which is extremely cheap to buy today.

This lab usually turns up on eBay a few times a year, and those in education who are interested in NAND gate based circuits buy it. The cost could be around the twenty-pound mark depending upon the condition and the number of interested bidders.

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