i have a issue with my power company (residential). my sub station also feeds a local cement plant and they have BIG electric motors. my power sucks to say the least.

i want to sample line voltage and capture it to a file. sample rate could be something like 5-10Hz and data is perhaps 8-9 bits wide.

any freebie stuff out there that can do this? my APC RS UPS cant do it (pos UPS).

thanks

 

You will need to use a transformer to step the voltage down to a safe level and isolate yourself from the line.

With the level low enough, any of the freeware sound card oscilloscope apps will work, and give you 16 bit resolution.

http://www.ehow.com/how_2278973_use-sound-card-as-oscilloscope.html

Ideally, you would want to sample in synchrony with the line, but that requires a zero crossing detector and uC.

Dataq has some data loggers that are quite inexpensive. The software is freeware.
http://www.dataq.com/products/startkit/index.htm

 

You will need to use a transformer to step the voltage down to a safe level and isolate yourself from the line.

With the level low enough, any of the freeware sound card oscilloscope apps will work, and give you 16 bit resolution.

http://www.ehow.com/how_2278973_use-sound-card-as-oscilloscope.html

Ideally, you would want to sample in synchrony with the line, but that requires a zero crossing detector and uC.

Dataq has some data loggers that are quite inexpensive. The software is freeware.
http://www.dataq.com/products/startkit/index.htm

ah, thanks.

and Dataq...... i am looking at some of there stuff for doing data logging for some of my automotive stuff........


wont a step-down transformer dampen the voltage spikes some due to its inductive nature? how about a full bridge rectifier directly on the 120v and then stepped down with a resistor divider? i'd be watching dc at this point, but just as good for monitoring....

 

Attaching to the power line is intrinsically unsafe. The circuitry is at line voltage, and always presents a lethal shock hazard. Even with a divider, the non-isolated voltage will fry your logger.

You will lose no significant data with a transformer. Consider that the power to your house is already going through a transformer on the power pole. Providing protection through the galvanic isolation of a transformer is necessary for safety. The voltage spikes will still show up.