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Why Do Calculators Have a Headphone Jack?
- simonblack 6y agoIts usually the older and cheaper calculators that have a jack. They're not a 'headphone' jack but a charger for rechargeable batteries or a battery-replacement source of electricity. Most of the time they are the narrower 2.5mm rather than a 3.5mm socket. I suppose that way back then, the headphone-style sockets were cheaper and more readily available than the pin-and-sleeve charging sockets we use today. I remember having a simple four-function battery calculator back in the early 1970s that cost $40 then (probably about $350 equivalent today) which had one of those 2.5mm sockets as a 6volt electricity source. This was before LED and liquid-crystal displays were cheaply available. So they used a gas-discharge display which was both expensive and power-hungry. A set of batteries would only last about six hours. http://www.vintagecalculators.com/assets/images/VFD_3.jpg http://www.vintagecalculators.com/assets/images/VFD_3.jpg