I/O: Controlling the Lamp
The goal of this project was to control a booklamp using a modified efe board. The unmodified lamp and power supply are shown below.
I had planned to use a relay so that I could easily control anything else that came along, but I ended up using a mosfet, effectively a solid state relay. For the MOSFET data sheet click here.
Because the lamp could not be run off of the power supplied by the serial port, I ended up using an external power supply. When I modified my circuit to add the mosfet and pads to solder the lamp, I also changed the schematic so that the external power supply was powering the chip. Now the board can run without being connected to a computer.
I addition to the circuitry on the board, I had to wire up the lamp. One problem I had was initially not making the power supply ground and the board ground the same, but the wire correcting this problem can be seen in the final photo. I also had to connect the negative part of the powers supply (the ground) to the negative battery terminal.
Original (left) and Modified (right) Schematics
Original (left) and Modified (right) Boards
My first attempt to make the board was on the vinyl cutter, but my classmates convinced me that the vinyl-cut board would come apart if I tried to move any parts around. (I also forgot to power the chip on this first board.)
Below are the final board and the powered lamp.