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Smart, web enabled fridge. Marty Lewis. INPUTS Weight/size Sensor Barcode Reader Touch Pad / Touchscreen LCD. OUTPUTS SVGA LCD. Basic I/O. INPUT AND OUTPUT Internet connectivity interface Ethernet, USB, 802.11g, Bluetooth, Modem. Load Cell / Strain Gauge
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Smart, web enabled fridge Marty Lewis
INPUTS Weight/size Sensor Barcode Reader Touch Pad / Touchscreen LCD OUTPUTS SVGA LCD Basic I/O INPUT AND OUTPUT • Internet connectivity interface • Ethernet, USB, 802.11g, Bluetooth, Modem
Load Cell / Strain Gauge Each load cell is comprised of a durable material with one or more strain gauges attached to or embedded in it. A strain gauge consists of a wire (or wires) that transmits a mild electric current. As the cell is subjected to weight, the wire in the strain gauge is altered or compressed slightly. The change in the wire results in a difference in the resistance to the current passing through it. Piezoelectric Piezoelectric sensors are embedded in a conducting material. When weight is applied, the pressure changes the voltage of the electrical charge flowing through the conductor. The sensors measure the change in voltage and calculate the load. The amounts from each sensor are added together. Capacitive Capacitance is a measure of the electrical charge stored between two electrodes separated by an air gap. As the electrodes are moved closer to or farther from one another, the air gap changes, and therefore so does the capacitance Weight Sensor Options
Capacities: 25 pounds-force Rated Output: 2 mV/V nominal Zero Offset: +/- 0.4 mV/V Overload, safe: 150% RO Overload, ultimate: 200% RO Excitation recommended: 5 to 15 Vdc Bridge Resistance: 5,000 . +/- 5% Bridge Configuration: 4-Wire closed bridge Insulation Resistance: >1000 M. @ 50 Vdc Operating Temp. Range: -20ーC to +125ーC Calibrated Temp Range: -20ーC to +100ーC Temperature Effect on Zero Balance: +/- 0.1% /ーC (+/- 0.06% /ーF) Temperature Effect on Span: +0.05% reading/ーC (0.03%/ーF) Long Term Stability: <0.1% RO per year Nonlinearity: +/- 0.5% RO Hysteresis: +/- 0.2% RO Nonrepeatability: <0.2% RO Electrical Termination: 0.040” dia. Gold pins on 0.2” pitch Circuit Board Mounted Load Cell
Most piezoelectric sensors weight sensors are for large weigh in motion systems. Could not find a good supplier / specs for a piezoelectric weight sensor. Piezoelectric sensor
Have many shapes and sizes. Can also have custom sizes made. Can choose a sensel density for your specific need I-Scan force/pressure sensor
Variable Force sensing 0 – 1 lb 0 – 25 lb 0 – 100 lb Custom Length 2” to 8” Flexi Force
Contact vs non-contact Contact Wand Non-Contact CCD Laser Projection (Omni-directional Laser) Decoded vs non-decoded Decoded Decode done by hardware in the scanner device Non-decoded Cheaper, can be done externally in hardware or software Barcode reader options
Free barcode scanner given out at Radioshack Can be modified to read regular barcodes Many websites offer drivers and documentation on how to unlock its capabilities Cue: cat barcode scanner
Connection to the online grocers / database: USB / Wireless USB 802.11a/b/g Bluetooth Wired ethernet port Modem External Interface
Remove dependence on a specific hardware internet interface Keep the communication level at the TCP/IP stack Allow any hardware interface to communicate via the TCP/IP stack Allowance for multiple connectivity hardware