The AM Forum

I want to monitor and record voltage variations.  I believe the correct technical term is “voltage data logging”.

My intention is to put one of my older legacy PCs (i.e.: Windows 98 Pentium) to this task but have no idea where to go without spending hundreds of dollars. 

Does anyone know of any inexpensive and readily available hardware/software to log AC (or DC) voltages over a defined period of time?

I’m a cheapskate so it has to be very cheap.

I'm a cheapskate too.  Nothing wrong with that.
Cheapskates will be having a surge in popularity in this economy.... ;D

Anyway,
We  cheapskates that I worked with in the past , used some of this stuff.
Works fine...easy to set up, comes with software, etc.
Cheap.

http://www.dataq.com/index.html

 8)

I hate to say it, but Radio Shack has an RS232 capable output DMM.

Does QUITE a bit, for what it is...  And the price is less than a hunnerd bucks.  Around xmas, was below 70.

According to the reviews online, it's not a bad meter...  AND there are adapters to do RS232 to Bluetooth, enabling FULL WIRELESS datalogging.

--Shane

I think that there is an inexpensive DVM with RS232 at MCM Electronics also.

Ac, Voltage divider into your sound card

Do you know if software is included to log?  Any idea how often it samples?  Perhaps I didn't state it initially, but I need something that will produce a graphical display and "catch" a voltage dropout of a few ms duration.  Perhaps this might be an excessive demand for an inexpensive DMM.

Perhaps in reality, I need an inexpensive means of turning my computer into a storage scope. 

What Frank said. Doesn't get any cheaper than that. Use Audacity or some other recording SW at a low sample rate and let it record.

DC you could build a VCO and record the frequency.

and the VCO ned no be costly, if all you want to do is catch a dropout to prove it's there. a cheap-o oscillator running off the supply (with suitable voltage divider if necessary) could do it. Even a neon bulb osc. if the situation is granular enough.

Thanks to all who responded. 

I had initially thought of using the sound card also suggested by Frank but I thought it was kind of a JS solution, particularly if something slightly more sophisticated was available cheaply.  But now the voltage divider/sound card appears to be the only cheap method so I guess I'll go with that.

Is this for 110 vac?
Some ups systems might log the voltage.
You know, the cheap ups systems people use to run their computer stuff, it has an rs-232 and/or usb port and software, I installed one that also measured room temps and would report that as well.

Once the batteries go bad in 5 years, people chuck them in the trash, and they should be cheap.
I used to take some to fests to power up the stuff so people could see it work, then sold the ups for $20.00.

Maybe look at tripp lite and apc web pages.
I was planning on taking a few to Timmonium to power up stuff and to sell....

In industry, they have power loggers, not expensive by industry standards...
 
Brett
N2DTS

Yes, Brett, it is for 110 VAC.  I didn't get that specific in my initial post because I thought having a universal test device might be helpful for more than just this one task.  I'm experiencing highly sporadic light flickering on more than one branch circuit and wanted to monitor different points in my circuit breaker panel.  Naturally if I can pinpoint the problem to be external to my breaker panel, I can rely on the power company to resolve it on their end.  The symptoms can occur frequently at times but then go weeks before occurring again.  Obviously it is difficult to pinpoint something that intermittent without an automatic means of recording the event.  And I wanted to do it with absolute minimal expense.

I've been using UPSes for several years but never utilized the RS-232 connection to the computer.  I wasn't aware that it can be used to record events. I thought that it simply provided an orderly saving of data and shutdown of the computer.  I'll have to hook it up and try that. Thanks for the tip!

Eric:
Do you have aluminum wiring at your location or is it all copper?

Hi Pete!  The service drop from the transformer at the road to the meter at the house is aluminum (200 amp service).  From the meter to the breaker panel is copper and all wiring inside the house is copper.  Aluminum is not permitted for inside wiring by code.