under $20 USD GM1020 Digital Light Meter with USB data logging

This thing doesn’t use a hardware level driver because it has a serial interface. It uses a prolific USB to serial chip which needs a driver. There are many different chips so perhaps you could try a different one. I came across this page, perhaps there’s something that may be of any use.
http://www.serialgear.com/usb-serial-adapter-drivers-windows-mac-linux.cfm

Any trick to getting it to upload. I click and nothing happens. The interval doesn’t change.

So I went on the link Nisei posted. I tried the 2009 “get all drivers link” and it fixed my driver problem. It connects flawlessly now.

I got mine without any software.
I looked for it on the internet without any luck. I contacted benetech and I’m waiting their answer.
Any chance any of you could share his copy? Thanks.

Sent you a PM.

Driver does't work with my Windows 8. Luckily, I have an old notebook with Windows 7 loaded. Installation was pretty straightforward. Somehow I am able to measure beyond 1900 mark. Will monitor if it will auto reset at one hour mark like what tek-0 has mentioned.

Up till this point, I would not recommend GM1020 to the rest yet.

I was able to make it work on W10 with the provided software from Maukka (BTW thanks again).
Please note that I had similar troubles with my expensiver luxmeter: after countless attempts I was able to make it work, but not 100% reliably on my W8.1 laptop. Usually I needed 10 minutes before being able to discharge the logs.

I tried once with my desktop with W10. Not only it did autoconnect to the software (a million year away from what I imagined could happen), but it works 100% reliably.
I believe the difference is in the bios and how the driver works with the motherboard. On my laptop, I found that everything that is not a pendrive thakes more cursing to work, compared to the widely compatible motherboard on the desktop I assembled.
Now I only use the desktop, and even for the GM1020 I won’t wase a second making it work on the laptop.

Now I will try to see how much difference is between a 20 and a 200$ luxmeter.

You guys using LuxLab or 3rd party?

luxlab

So now after some discussion, is this still a high-value option? Or is there a better model I should be looking at for ~$20?

It depends on what you want to do. There is no other budget alternative for a luxmeter with datalogger in that price range. I use this model since several months and i cant say anything bad about it. The thing with cheap luxmeter devices is that they are probably not as accurate compared to higher prices devices but that dosnt matter at all for runtime tests or ceiling bounce tests etc… because you actually calibrate the device with your reference flashlight, it doesnt matter if it will show the true lux value @1m for example. I have three luxmeters and all show different lux values, sometimes 5k difference. For example luxmeter A shows 44k lux, the other one 39k lux. I think this device measure a bit to high but for runtime tests it doesnt matter. You have to deactivate the auto shutdown function.

I will be using it to measure throw numbers and probably make a sphere or PVC tube at some point for lumens. I don’t necessarily need the logging function. First priority is accuracy and consistency, but must be under $25

I’ve got two of these. They differ about 5-15% from each other depending on the brightness/cct/cri of the light used. Haven’t looked into it more though.

for a sphere its ok because you calibrate it with your reference light sources, so it doesnt matter if its off or not. Remember for a sphere you want a luxmeter with a separate sensor, not the one piece design like this one. If you dont need the logging function than you can buy any other budget luxmeter, i like this one

So you guys pretty well ironed out all the issues? Is this a viable option to use for runtime testing?

Also kinda curious how y’all go about your tests. I use my lumen tube and have a series of alarms set to manually collect data points. Gets pretty dang tedious; A data logger would be a huge step up.

What programs do you people use to create runtime graphs? Google spreadsheet seems to have some hiccups when I input thousands of numbers to it and do some math on them, so I’d like to have some better options.

counterfeit prolific chips.
use the driver supplied with the unit.its patched to run the counterfeit chip.

Excel.

Someone please do review this. I don’t need accuracy to 4 decimal places, I just want to be in the ballpark about flashlight runtimes and light intensity. This might be the next thing on my “want” list.

Questions.

  1. Does the entire light test have to be in a dark room? My tests might last 24 hours or more. This could be a problem because I don’t have a spare bedroom.
  2. Can I set the time to log data? I might only want to log data once every 10 seconds.

Thanks!

you may be able to add piece of paper or other “diffuser” to the one that reads high…

fwiw, I “calibrated” the cap from a vitamin jar, to show 1 lumen Low with a ReyLight Tool. (with a couple of layers of paper under the cap),

with that calibration, I wondered how it would read on High so I tested 3 of my Lumintops w Nichia
the actual reading came in 6% below spec for the ReyLight on High

here is a Lumintop Tool w Nichia (on a Maratac body), it measured just 2% below spec

that same “calibration” produced almost exactly factory spec High on my Worm (spec is 80 lumens)

the largest variations imo are caused by differences in battery levels. there are also differences between the individual drivers in each light.
Notwithstanding the factors that cause inconsistency between specs and individual lights, I believe the “calibrated” diffuser is reasonably consistent at both low and high lumen levels.