“Counting box” also saves calculators from small children

box

[Nathan]'s son really loves numbers and counting, and one of his favorite things to do is add 1 to a calculator over and over again. Being the awesome dad that he is, [Nathan] built his son a counting box that has a 10-digit rotary switch and two arcade buttons to add and subtract. One goal of the project was to have the counting box retain memory of the display while being powered off. The … [Read more...]

Gigantic ball-manipulating binary computer

digi

The folks at Evil Mad Scientist Labs just put up a post on the giant mechanical binary computer they brought to last month's Maker Faire. As a faithful reproduction of the Digi-Comp II from the 1960s, every operation is powered by balls falling onto levers. Unlike the original, the larger version is powered by billiard balls instead of half-inch marbles. The Digi-Comp II is able to count, add, … [Read more...]

Minimalistic 555 Adding Machine

555-adder

How many 555 timers does it take to add up two 10 digit numbers? [Alan's] 555 Adding Machine does it with 102 of them, he designed the machine as an extreme entry to the 555 contest and the original plan was to make it even more complicated. This machine uses the 555's to implement a nine decade accumulator and multiplexer, all inputs are managed by an old school dial from a rotary phone which … [Read more...]

Relay Calculator

Screenshot-16

Calculators are a handy tool to have around in just about every application. We often take them for granted today, but even when I was a kid they were still sort of expensive devices that you put thought into buying. Illustrating just how far we have come is this awesome Relay Calculator brought to us by [Team 619]. Featuring an optical slider input system, the user can select any two 4 bit … [Read more...]

Analog computer does math

analog-computer

This analog computer can multiply, divide, square numbers, and find square roots. It has a maximum result of ten billion with an average precision of 2-3%. [Miroslav's] build recreates something he saw in a Popular Electronics magazine. It uses a resistor network made up of three potentiometers with a digital multimeter is an integral part of the machine. To multiply a number you set the needles … [Read more...]

Make Your Own Odometer from Scraps

Operation

For those out there who would enjoy a quick and interesting weekend project, this odometer made by [PeckLauros] is for you. Featured on Instructables it is made from the simplest of materials including some cardboard, a calculator, wires, glue, hot glue, magnetic drive key, an old CD and a reader, and a rubber band.  The magnets, when attached to the CD work in a calculation to add 0.11m to the … [Read more...]

Calc is high-tech for 1970′s homebrew

1970-homebrew-calculator

Just one look at that banner image and you've got to be thinking "that's old"! This 1970's era home made calculator used a 4-function calculator IC that was quite advanced for its time. The only problem is that the chip couldn't do anything other than calcuations, which left it up to the maker of this dinosaur to get the display and keypad working. Circuit boards were made by drawing on copper … [Read more...]