DATAMATH CALCULATOR MUSEUM
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DATAMATH CALCULATOR MUSEUM |
Exactra 22 by Texas Instruments
| Date of introduction: | October 1974 | Display technology: | LED-stick w/o lens |
| New price: | Display size: | 8 + sign | |
| Size: | 5.1" x 2.9" x 1.3" 130 x 74 x 34 mm3 |
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| Weight: | 5.1 ounces, 144 grams | Serial No: | 2200004547 |
| Batteries: | 3*AA | Date of manufacture: | wk 44 yr 1974 |
| AC-Adapter: | AC9160 | Origin of manufacture: | USA |
| Precision: | 8 | Integrated circuits: | TMS0803, SN27882 |
| Logic: | Chain | Displays: | |
| Memories: | |||
| Program steps: | Courtesy of: | Joerg Woerner |
The
Exactra 22 is yet another member in the Exactra line from
Texas Instruments. Compared to the Exactra 21 you'll notice an additional
connector for an external power supply.
Dismantling
the Exactra 22 revealed a small surprise, the LED-display found in this
particular calculator was manufactured by Bowmar. We know the Opto-Stick display
with its small numbers already from the TI-2500B. Don't miss an overview of all
Exactra Calculator LED Displays.
The
double-sided printed circuit board (PCB) of the Exactra 22 seems to use similar schematics as
the Exactra 21 but a different layout to accommodate the extra power connector.
We identified a
TMS0803 single-chip calculator circuit and
a SN27882 7-channel digit driver
manufactured by Texas Instruments for the LED display. Two NPN bipolar junction
transistors (BJTs) with additional resistors are used for the remaining digit
drivers. The other parts on the PCB form a small power-converter to generate the
VDD and VGG supplies of the TMS0803 chip with three AA-sized batteries.
Don't miss the Exactra 23 loaded with all features.
If you have additions to the above article please email: joerg@datamath.org.
© Joerg Woerner, December 5, 2001. No reprints without written permission.