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Thread: Opple Light Master III Bluetooth and App based lighting sensor.

  1. #1

    Default Opple Light Master III Bluetooth and App based lighting sensor.

    I'm currently looking at installing LED strips in my living room. After I bought a few fixtures with adjustable color temperature which turned out to have rather miserable color rendition, I decided I should have a tester or measuring device. The cheapest one that I found which claims to be able to measure lux, CRI and color temperature is the Opple Light-master-III. I bought it from an Amazon dealer here in Germany for ≈39 Euro plus shipping.

    It came in a rather small box, together with a pouch.

    The sensor unit is small, 60 x 38 x 20 mm. An 18650 is taller.

    It has a micro USB socket at the base, to recharge the built in battery. When powered by USB, a very small and not very bright LED next to the socket lights up. It looks orange-ish on the photo, but to my bare eye, it looked green. I have no explanation for this discrepancy. It says "Input current: 40mA" as you can see, but when I powered the unit through a USB tester, it measured only around 18mA.

    When you push that bottom side, the sensor slides out at the top. That also powers the unit up.

    Another very small LED starts flashing slowly, signalling that the unit is ready to pair with the app in the smartphone.

    On the back of the cardboard box that the unit came in is a QR code. If you scan it with your smartphone, it will bring you to Opple's website, where you can download the Light Master Pro app. You can also find it in Google's playstore. I think there's also an Apple version of the app, but I didn't verify this.

    The app wants to know where you are, it will not continue if you don't grant it access to your location.

    The app also establishes the bluetooth connection to the sensor. You cannot establish the connection from the smartphone's bluetooth settings. When you pair the units for the first time, the app asks you to bring the 2 in very close proximity. It then connected quickly.

    Once the connection is established, the LED lights up continuously.

    When using the unit again later on, it will connect also from a distance, as usual with bluetooth. So far it always connected reliably - within a few seconds - when I tapped the Start button in the app.

    [to be continued]
    Last edited by wus; 04-15-2021 at 12:15 PM.
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  2. #2

    Default Re: Opple Light Master III Bluetooth and App based lighting sensor.

    The app is version 1.0.4 Build:8. The start display looks like this, ...

    ... except that instead of the red STOP button it first shows a blue START button. When you move the sensor, or the light changes, you can see the shown values change, probably once every second.

    Swiping left brings up the chromaticity diagram. Unfortunately it is rather small and can't be zoomed.

    When you move the sensor to light sources with different colors, the cross-hair dot that's shown at about 5000K on the black body locus in my screenshot moves around live in the diagram.

    At the bottom of the screen there's a button "flackern". I guess in English it will say flicker, but since I can't switch my German smartphone to English, I can't be sure.

    When you tap it you get an evaluation of the flicker risk ("Risikoabschštzung" in my screenshot, as before I'm not sure what it actually says in English). My desk is lit by high CRI daylight flourescents driven by HF electronic ballasts. They have very little flicker, so there no risk ("Kein Risiko").

    If you tap on "Rohdaten" - raw data - you get to a sort of oscillogram, showing a time base and the fluctuation of brightness over time, i.e. modulation, or flicker depth.

    Light produced by a 12V 20W tungsten-halogen MR16 driven by a traditional 50 Hz transformer produced this:

    Still no noteworthy flicker... so let's try a Philips ExpertColor 230V GU10 LED spot:

    This has considerably higher modulation. The app shows "Hohes Risiko" here, high risk.

    However, if you count the milliseconds from dip to dip in the waveform shown above, the cycle is 10ms, so it's a 100Hz flicker. That's not so bad, much better than if it was 50Hz. I never noticed this lamp's flicker, and I know that I am rather susceptible to flicker. At the times when computer displays were still CRTs, I could never stand frame rates below 80 fps for long.

    [to be continued]
    Last edited by wus; 04-15-2021 at 03:51 PM.
    leave nothing but footprints, take nothing but memories

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