Dorm Room Power Monitor


Need a way to display power consumption & log results. Moreover, it should work with any standard parallel port printer to create a power usage report based on time of use.


The Avr 8535L. plenty of I/O and ports to spare. First: find an LCD. for this project im using the 

cheap and huge allelectronics display. [256X128]. i had already modded it to add in those el panel backlights. Moreover. im using the exact same simple fm transmitter that i mentioned on the current projects page. The reasoning for the rf transmission is that its more functional to put the collector device (powered by AA's) clamped around the power outlet than if I were to require that the measuring device be tethered to the display/printer.


The underlying reasoning for this project is to not only create a useful power measurement tool, but to also use this in my natural resource economics project. The theory is that if you are able to monitor the power you consume you will consume less. 

    [basically Im building an open source 'powermizer' and seeing if there is a significant difference by testing it on         other dorm inhabitants.]

The Hardware

    The Inductive power monitor
    The rf stuff
    The display [power components]
    The Core
    The cap. touch sensors [rc]
    The speaker

The Code
    Driving a printer with a microcontroller?.. Yep, with 9 lines
    Receiving serial from RF [getting rid of interference]
    Making the LCD Work [text 
    The LCD continued...[graphical generator]
    Making the retro sounds

The Results

    The first working lcd vid {or why i need to get/make a new video cam}

Problems/ solutions

      Measuring power

Linearlly extrapolating current usage based upon the voltage measured across a hand wound torroid was sufficient for this project because it required the least components and no specialty parts. However, the power monitoring system doesnt just measure resistive loads, laptop power suppplys (normally capacitive) and speaker amplifiers (inductive) are reactive loads, so there is an imaginary component to the power being used. This method doesnt necessairally capture all of these components, whereas measuring the phase difference between line voltage and current draw would have given a better picture.



Rensselaer Polytechnic Institute 
Electrical & Electrical Power

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