Advanced scientific calculators are getting more powerful, yet they’re usually powered by a small *non-rechargeable* battery and the size of the solar panel on there is incredible tiny. How does a panel that small even make a significant contribution to the power available given that it can’t be used for recharging the battery?
In: Technology
Small solar panels don’t generate that much power, but it just so turns out that calculators don’t need that much power! It’s basically the only electronic device that can be solely powered by constant light.
People want them because it means they don’t need to replace the batteries as much, or in some not at all.
Most calculators do still have a battery because not all environments have bright enough lights to generate the electricity, but when you do have enough power then you don’t have to use up power from the battery.
I had a scientific calculator in the 80s, decent-size calculator, pretty big solar panel. But since then a couple things have happened. One, solar panels have gotten more efficient. Two, microprocessors use thousandths of the amount of power for the amount of work they do. Basic scientific calculator functions require almost no power these days.
To give you an idea of power usage over time: An 80386 DX-25 processor then took .6 Amps to operate, and that’s just the processor, not associated RAM, storage, etc. An Apple Watch can run all day on a battery that would only power that 386 for half an hour, and of course the watch is FAR more computationally powerful than that 386.
And the chip in your calculator is likely not even a full-blown CPU. It’s more akin to a microcontroller one might find in an electronic thermostat, but customized for math instead of managing temperatures. For example, it needs almost no memory address space, so that can be cut to a minimum to save cost. But it may have some large registers to hold floating point numbers, and hardware-encoded mathematical functions (like input A Sin input B completes quickly because there’s a Sin function in hardware to do that).
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