Assignment 5
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.
![](parts.jpg)
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
![](lampsch.bmp)
Original (left) and Modified (right) Boards
![](lampbrd.bmp)
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.)
![](vinylboard.jpg)
Below are the final board and the powered lamp.