quidam34's Profile

A similar project, which uses a PIC microcontroller and an analog multiplier to compute the power: This node monitors the instantaneous current, voltage, frequency, and real power consumption of my home. Voltage is monitored with a dedicated miniature transformer, the current is measured using a home built current transformer that clamps around the incoming power feed, and the real power is calculated with an analog multiplier followed by a low pass filter to obtain the DC component (real power). These analog quantities are then fed to a 12-bit A/D converter driven by a '77 PIC. The circuit gains get me a resolution of 5 Watts. As a result I can even see the effect of turning on one lamp.

This device monitors household power usage and logs it to an SD card. A simple analog front-end amplifies the signals from voltage and current detectors and an ATmega168 microcontroller computes the power consumption using the formula P=V*I. The voltage and current are each sampled at 9615 Hz so the integration should be fairly accurate even for highly non-sinusoidal loads such as computers or fluorescent bulbs. A graphical LCD shows the power usage as a strip chart and can also act as an oscilloscope to display the voltage and current waveforms. The current is amplified in three stages (1x, 10x, and 100x) so that different gains can be used giving accurate readings for both high and low power usage.

John Park hacks a Wii controller and turns it into a personal flight recorder that can sense and measure the stomach-churning G forces of roller coasters and other high-speed, high-risk activities.