Capacitive keyboard - a solid state 'keyless keyboard'

4-46 - elektor april 1982 capacitant keyboard • J• keyboard a solid state "keyless keyboard" The choice and price range of available computer keyboards is today swiftly approaching a level of infinite proportions. As a result, many readers prefer to build their own. A system using mechanical keys, although being simple, is relatively expensive. Capacitive touch activated keyboards are an economical alternative. They achieve a high standard of reliability, without the need to use expensive conventional mechanical equipment. Small, single-board microprocessor sys- tems require a keyboard consisting of between 10 and 20 keys. Keyboards of this kind look very simple, but are surprisingly expensive. Normal use sub- jects the keys to considerable mechan- ical wear, making frequent replacement necessary. The use of conductive rubber and "hall" effect elements in one way to overcome this problem. But a more effective solution is a capacitive keyboard using touch activated keys, ther...