Giant Calculator With 9" x 1" LCD
- Thread starter pilko
- Start date
hippy
Ex-Staff (retired)
I've got something very similar, A4 sized and black, had the same thoughts.
The problem is likely that the LCD is driven by a micro designed for doing that and the LCD uses a multiplexing scheme which require stepped-analogue voltages and correct phasing. It's perhaps possible with a PICAXE but would likely be hard and in keeping the signals within spec and at speed - IMO, but don't let that put you off experimenting.
It might be possible to control the keys so you could create a counter. The first thing is to take the back off and count the connecting wires to the LCD.
Added : There are chips designed to drive multiplexed LCD so that's an option.
The problem is likely that the LCD is driven by a micro designed for doing that and the LCD uses a multiplexing scheme which require stepped-analogue voltages and correct phasing. It's perhaps possible with a PICAXE but would likely be hard and in keeping the signals within spec and at speed - IMO, but don't let that put you off experimenting.
It might be possible to control the keys so you could create a counter. The first thing is to take the back off and count the connecting wires to the LCD.
Added : There are chips designed to drive multiplexed LCD so that's an option.
Last edited:
hippy
Ex-Staff (retired)
I personally would work on the principle that it will be multiplexed, so bear that in mind before purchase. Alternatives for cheap experimentation are LCD clocks and smaller calculators in charity shops etc.
Clock 7-segment displays are often difficult to drive as they often aren't multiplexed as standard 7 x N digits but 2 x M segments or in weird charlieplexing configurations.
Clock 7-segment displays are often difficult to drive as they often aren't multiplexed as standard 7 x N digits but 2 x M segments or in weird charlieplexing configurations.
westaust55
Moderator
At $20 just for the 1 inch high LCD (looks like about 9 digits), a look at Futurlec.com might be worth while.
You can buy some 1 inch high 14-segment displays at US$1-50/$1-60ea
While higher current consumption, the 14-segment format would be more versatile for a multchar display.
http://www.futurlec.com/LEDDisp.shtml
Part No. Description More Info In Stock Package Qty. Price US$
14SR10013AS Single Hi-Red 1.0" CC 14-Segment LED Display No 1 $1.50
14SG10013AG Single Green 1.0" CC 14-Segment LED Display No 1 $1.60
You can buy some 1 inch high 14-segment displays at US$1-50/$1-60ea
While higher current consumption, the 14-segment format would be more versatile for a multchar display.
http://www.futurlec.com/LEDDisp.shtml
Part No. Description More Info In Stock Package Qty. Price US$
14SR10013AS Single Hi-Red 1.0" CC 14-Segment LED Display No 1 $1.50
14SG10013AG Single Green 1.0" CC 14-Segment LED Display No 1 $1.60
If you hack the keypad but keep the electronics intact, i.e. the Picaxe simulates key presses instead of trying to drive the display directly, you could easily display arbitrary numbers. Just have the Picaxe "press" the appropriate sequence of numeric keys and finish with "pressing" the "=" key. Then at the next sequence the display would automatically get cleared before the next number. ALternatively start each new number entry with the "ON/C" key.
The size of the electronics behind that huge calculator is probably minuscule in comparison, so you could get rid of the physical keypad and put the thing into a smaller box if needed.
Wolfgang
The size of the electronics behind that huge calculator is probably minuscule in comparison, so you could get rid of the physical keypad and put the thing into a smaller box if needed.
Wolfgang