Simple hack of DX light meter for logging lux data

[minisystem]

I got one of those cheap digital light meters from DealExtreme. While I can't verify its accuracy, it seems to be precise enough for relative measurements. I wanted to be able to log the lux data in my computer, so I opened it up and started poking around the PCB to see if I could get a useful signal to bring into the computer. To keep things simple, I decided not to get into the signal going from the ADC into the LCD but instead found the main variable voltage from the sensor amplified by an opamp. The LCD displays a base 10 multiple of this voltage, so converting from volts to lux is easy. I'm most comfortable using the Arduino platform, so I used it to read the voltage, convert it to lux and then send it to my laptop via serial interface. More details here if anyone's interested: http://minisystem.blogspot.com/2011/12/logging-lux-data-with-hacked-dx-light.html

The end result (output going from Arduino to an LCD module):

 

[chesster6969]

will you be able to read voltages above 1.1v on your Arduino? ive been looking into building an arduino.
thanks

 

[minisystem]

Yeah, the Arduino can read 0-5V with 10 bit resolution when using the default reference voltage. I just happen to need the 1.1V reference for another aspect of my data logger.

 

[HKJ]

Instead of the Arduino it is also possible to use a logging DMM, that is probably a lot easier for most people.

 

[minisystem]

Instead of the Arduino it is also possible to use a logging DMM, that is probably a lot easier for most people.

Fair point. I've never used a logging DMM. That would definitely be easier (although Arduino is pretty easy to use ie. if I can figure it out then almost everyone else should be able to as well!).

 

[ahorton]

This is very cool. Well done.

Much better than setting up a camera on time lapse like I do!