Looking for Automated Runtime Measuring Equipment

I enjoy doing runtime tests of the various lights I own. I like to compare brightness to runtime, even along the same product like. The way I currently do this testing is very manual and quite frankly a pain in the a**. Roy is the only one that I know of who has a fairly automated system of performing runtime tests, however from what I understand, some of the equipment is no longer being sold.

All that being said, what do I need to purchase that would allow me to point a light at a light meter and record live runtime data on my laptop. Currently, the only equipment I have now is the LM631. I'd like something (even if it means that I have to purchase a different light meter) that would allow me to walk away while the test is running and the data will be recorded (live) on the PC.

Re: Looking for Automated Runtime Measuring Equipm

I think your LM631 has a voltage output so all you need is a multimeter with a PC interface and some logging software and you should be set.

Of course if you want something REALLY crude and simple, you could use a webcam pointed at your LM631 readout. Those often come with "home surveillance" programs that snap a picture every minute or however often you specify.

Re: Looking for Automated Runtime Measuring Equipm

Or, there is the ghetto way. Get yourself a videocamera (good for two hours) or a webcam that can snap pictures every few minutes.

Set the meter next to an alarm clock, and set thecamcorder to record. Then, after the test if over, just fast-forward and type in the number every five minutes. I admit that this is not the "automated" way, but it IS less of a PITA. It may also be able to be done with items that you already have in your house!

If you do not like this idea, then you only have two other choices...

1) Use a light meter with some sort of RS-232 interface. This may get expensive.

2) Use your own light sensor (solar cell, CDS cell, etc.) hooked up to some sort of A/D converter (could be a meter, data acquisition board in your PC, microcontroller running custom firmware hooked up to your serial port, etc.). This would work, but it would NOT be calibrated the way that a light meter would, so you would not get a direct lumen reading.

Re: Looking for Automated Runtime Measuring Equipm

I started with a data logging multimeter that I found on clearance at Radio Shack and a photocelll from a solar power demo kit, also from RS. That works fine as long as you are ONLY interested in how long the batteries last in a flashlight. The light meter that I now use is more of an adapter than a light meter in that it needs to be pluged into a digital multimeter that has mVDC scales. It is calibrated so that 1 mVDC = 1 Fc.

I believe Radio Shack still sells datalogging multimeters with RS 232 serial ports.

I was lucky in that my total cost for my runtime setup is about $100.

Re: Looking for Automated Runtime Measuring Equipm

I just ordered an Extech #401036. It appears that it will suit my needs. What's nice about this meter (according to the documentation) is that the meter has a 16,000 sampling memory buffer, so I can record samples and dump them into the application logging software at another time.

Re: Looking for Automated Runtime Measuring Equipm

I also do mine tests with a digital camera. I just set the camera to take pics at given intervals, either 1, 2, 5 or 15 min intervals depending on how long I expect the light to run. Then I turn the light on and aim it at the light meter and set the camera and walk away. Then I just step through the images and record them in an excel spreadsheet. I usually get my wife to look at the pics and I am on the computer next to her entering them in excel. A pain, but much better then doing it manually. I can also start it and leave, go to bed or work or whatever.

Re: Looking for Automated Runtime Measuring Equipm

Hey Ray, If your going to get rid of your LM631, I'd be interested.


Peter