For this assignment I took apart the black and decker PlantSMART sensor for growing plants. I thought it would be helpful because it includes a variety of sensors that could be useful toward the Bijoux modular jewelry kit that I plan to incorporate sensors into.
Circuit: most of these parts can be purchased through digikey or similar parts supplier except where otherwise noted.
- 1 microchip PIC18F4550
- 20 capacitors, different packages sizes all SMD, both ceramic and tantalum
- 24 resistors, different package sizes all SMD.
- 1 16 mHz crystal oscillator
- 2 Inductors
- 1 pushbutton switch
- 1 piezo speaker
- 1 male and 1 female usb adapter
- 1 battery holder and AAA battery
- 2 voltage regulators
- 4 diodes (including LED’s)
- 1 temperature sensor (thermistor)
- 1 light sensor (phototransistor)
(Probe PCB that is exposed to the elements has special coating, as well as the exposed sensors)
- 1 fertilizer sensor (don’t know what it is – this is a non standard part)
- 1 simple sensor for conductivity/moisture (this needs to be fabricated on a case by case basis)
- Vinyl flower
- 4 piece injection molded plastic enclosure, white and opaque
- 1 injection molded plastic light housing, white and semi-opaque
- Silicon rubber coating around enclosure to protect from water
- Silicon rubber battery holder
- 2 small screws
- PCB milling, machine stuffing of the components. A few of the components may be hand soldered
- Injection molding of enclosure. Machined
- Placement of finished circuit PCB on half of enclosure. Other half of enclosure placed onto board. Insertion of two screws. This assembly is by machine. I am now calling this the circuit enclosure.
- The circuit enclosure is dipped entirely in silicon/rubber coating. Machine or manual.
- Addition of vinyl flower and light cap. This is either by machine or manually.
- Probe PCB is inserted into base of circuit enclosure and glued/sealed in. This is done manually.
- Insertion of battery into unit. This is done manually.
Cost of device is $17.99, so it was likely around $4 or $5 dollars to make. EasyBloom was an earlier version of this device (essentially the same thing) that originally sold for $64.99. This shows the difference in cost at different quantities.