• About EEVblog

    Check Also

    EEVblog #1056 – Digilent Open Scope MZ Review

    Dave looks at the Digilent Open Scope MZ Review, an $89 open source oscilloscope, logic ...

    • Pingback: EEVblog #869 – Counting LED Photons! | WTS Connects()

    • Pingback: EEVblog #869 – Counting LED Photons! | Contract Manufacturing Company()

    • LinkZ

      What’s your job?

      • Stan

        Did you try using the R&S 1202 to capture and count the photon pulses? It looks like the data sheet claims 2ns pulse detection and pulse counting and averaging functions

        Great video.


    • Nic Perrin

      I’d have used the Frequency counter with a gate time of 60 seconds. Wouldn’t need averaging with a minute’s worth of photons. Can divide the count by 60 for photons per second. Can still use a scope to see a visual representation of pulse density, but get an accurate count without messing about with memory depths, timebases, peak detect mode etc..

    • Geoffrey Feldman

      Here is a task for the photon counter, do non LED diodes (or transistors) emit some photons? perhaps not enough to see but maybe they also do emit a few photons. Some diodes are in a clear package, others you may be able to expose their insides. If you connect an LED to a multi-meter and shine a bright light on it – there will be current. The voltage will be about 1V or so. Jumbo Led’s are best. Current flows out the opposite of how it flows in when producing light. Another trick – charge the LED junction capacitively with small pulses, just enough to get a bit of visible light. Then measure the charge and its decay over time. It will decay faster when exposed to light. LED’s are sensitive to a slightly shorter wavelength than what they put out – another little quantum puzzle.

    • Cliff Jones

      Back many years ago I did some experiments without much thought, and found out that LEDs are also light sensitive. Hooked up a voltmeter and wow actually got a reading, So I also measured current, so anyway it might be used as a cheaper photo cell too. Or a spectrum analyzer depending on the LED colors used, infrared, ultraviolet, white or? use an amplifier and test for atmospheric light brightness or change in sun intensity.

    • George Herold

      Hi Dave, I did a similar measurement with LEDs and just a photo-diode (TIA) circuit. Here’s a dropbox link to the data, https://www.dropbox.com/s/atyo4uvsb09fgd7/LED-PD.BMP?dl=0 I did a log log plot. A slope of one (1) would be linear… at low currents to slope is ~2/3.

    The EEVblog Store generally ships twice a week, on Tuesdays & Fridays, Sydney time. Dismiss