Thursday 23 February 2012

Week 6


The blinds are moved up and down using servo motor. The motors are optoisolated using 4N35 isolaters and powered by a ULN2003A Darlington Array. The stepper motors are used because of their accuracy since the blinds are expected to stop at specific positions depending on the user's previous preferences. They both drive a single gear that increases the torque in the system, allowing shades to be reaised smoothly. Spools are used to roll up the string that holds the window shade. Pulleys are used to redirect the force of the pulling so that the single gear and rod are able to raise and lower the shade. The string goes through the holes of the original window shade frame, so that its outside appearance looks exactly like a normal window shade.

Tuesday 14 February 2012

Week 5


Finish construct circuit and ready for testing.

PIC is a family of modified Harvard architecture microcontrollers made by Microchip Technology,derived from the PIC16F877A originally developed by General Instrument's Microelectronics Division. The name PIC initially referred to "Peripheral Interface Controller". PICs are popular with both industrial developers and hobbyists alike due to their low cost, wide availability, large user base, extensive collection of application notes, availability of low cost or free development tools, and serial programming (and re-programming with flash memory) capability.

Friday 10 February 2012

Week 4


litar power supply

A power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy (e.g., mechanical, chemical, solar) to electrical energy. A regulated power supply is one that controls the output voltage or current to a specific value; the controlled value is held nearly constant despite variations in either load current or the voltage supplied by the power supply's energy source.
Every power supply must obtain the energy it supplies to its load, as well as any energy it consumes while performing that task, from an energy source. Depending on its design, a power supply may obtain energy from:
  • Electrical energy transmission systems. Common examples of this include power supplies that convert AC line voltage to DC voltage.
  • Energy storage devices such as batteries and fuel cells.
  • Electromechanical systems such as generators and alternators.
  • Solar power.
A power supply may be implemented as a discrete, stand-alone device or as an integral device that is hardwired to its load. Examples of the latter case include the low voltage DC power supplies that are part of desktop computers and consumer electronics devices.
Commonly specified power supply attributes include:
  • The amount of voltage and current it can supply to its load.
  • How stable its output voltage or current is under varying line and load conditions.
  • How long it can supply energy without refueling or recharging (applies to power supplies that employ portable energy sources).

Friday 3 February 2012