Date of intro: oct-1972,
Classification: / Documentation / Article,
Serie-members: (Docu_Articles): 197209: The Wireless World Desk Calculator (part-1) (Part-1); (Docu_Articles): 197210: The Wireless World Desk Calculator (part-2) (Part-2),
Publisher-1: WIRELESS WORLD, Publisher-2: ALEXANDER Roger / CRANK Brian,
Info: This second part of the article focuses on the construction and operation of the WIRELESS WORDLD Desk Calculator.
Unlike most construction projects in the magazine, very detailed instructions are provided because every component in the kit has a specific position.
The complete kit was sold for £39.25 and contained all the necessary components.
A major concern during construction is protecting the TEXAS INSTRUMENTS: TMS1802NC MOS integrated circuit.
Because MOS components are extremely sensitive to static electricity, the chip is transported in conductive foam.
Builders are instructed to discharge static electricity from their bodies, avoid touching the chip's leads, and use a properly earthed soldering iron.
Another difficult part is assembling the nine LED numerical displays.
Together they require 81 solder connections in a very small area, so a fine, low-power soldering iron and careful work are necessary.
The article then gives step-by-step instructions for assembling the case, power supply, switches, main circuit board, keyboard, integrated circuits, and display board.
After assembly, the calculator must be tested.
The power-supply voltages are measured first, after which a functional test checks whether the keyboard and display work correctly.
The article strongly warns that parts of the circuit are connected directly to mains voltage during testing and can therefore be dangerous.
The final section explains how to operate the calculator.
It describes the functions of the multiplication, division, addition, subtraction, clear, and constant keys.
The display can also indicate negative numbers and different types of overflow.
The authors provide many practical examples to demonstrate the calculator's capabilities. Besides normal addition, subtraction, multiplication, and division, the calculator can use its constant function for repeated calculations.
More advanced examples include finding reciprocals and square roots and solving electronics calculations such as resistance, resonant circuits, and bandwidth.
In short: the article is a practical guide to building, testing, and using an early electronic desk calculator.
It shows that although integrated circuits had greatly simplified calculator electronics, assembling such a machine in 1972 still required careful soldering, technical knowledge and attention to electrical safety.