Sharp EL-825
Sharp EL-825
Display is 8 digits, LCD.
4-function, %, memory, square root.
Large fold up solar cell.
Credit card size (but a little thicker) -
- Folded 98 x 68 x 12 mm (3.9" x 2.7" x 0.5").
- Open 98 x 132 x 6 mm (3.9" x 5.2" x 0.5").
Size of solar cell 76 x 50 mm (3" x 2").
Made in Japan.
Here the calculator has been opened up. It is interesting to see that there are two cutouts for button cells in the circuit board (at its top right here) and printing to show which way round they should be inserted (too feint to show up here). This shows that this is probably a conversion to solar power from a calculator using button cells.
This model is a bit of an enigma since there is little information about it. The folding design and the photocell are the same as that of an early Teal model (the Photon III which was advertised as the first solar powered
calculator), but the keys and display are different. Information about when it was first sold is lacking, and it appears to have just been sold in part of the U.S.A.
The integrated circuit is embossed with either "6S" or
"S9". If the number is a year code then this would indicate either 1976 or 1979, but 1976 is rather too early for a credit card sized calculator (since the Casio Mini-Card LC-78 from 1978 is credited with being the first credit card sized calculator), and 1979 is too late for such a huge solar cell on a calculator.
If you have any more information about this calculator please get in touch with us.
The early solar cells were very inefficient. This one requires quite bright light before the display appears and the calculator operates. Soon, with improvements in the technology (and also in the power requirements of the electronics), the size of the solar cells dropped to a fraction of this one.
It is interesting to see how the designers have managed to produce a credit card calculator with this large size of solar cell by folding the calculator in the middle.
Also see the Sharp EL-8026 and Teal Photon, two of the first solar powered calculators.
