Computing stuff tied to the physical world

Posts Tagged ‘Metering’

Better Mousetrap

In AVR on Dec 12, 2008 at 15:48

Now that RF transmissions work better, it was a small step to create a better house usage monitor. This one supports four sensors:


Only two sensors are being used so far (all sensor inputs are identical).

Sensor #1 watches the electricity meter rotations using the SY310 sensor:


Sensor #2 is a QRD1114 which tracks a little mirror mounted on the last digit “0” of the gas meter:


The sensors were described in a previous post. Proper positioning turned out to be crucial, so there’s a fair bit of scotch tape to hold everything in place!

IR Sensors

In Uncategorized on Dec 8, 2008 at 15:35

Here are two new home-made sensors, improving on this one they will soon replace:


The top one uses a QRD1114 sensor, which produces an analog signal, whereas the lower one is based on the SY310 with a built-in comparator to generate a digital output. The intended range is around 5..15 mm, hopefully just right to detect the 0-digit reflector on the gas meter and the the rotations of the energy meter, respectively.

Both of these sensors are connected to a 3-wire audio jack cable: shield = ground, ring = +5V, and pin = signal. Both sensors use a 330..470 Ω resistor to drive the IR-LED and a second one of 10..100 KΩ as pull-up for the output signal.