Measure the flickering of the lamps

Why measure the "Flicker" of the lamps

It "Flicker", in Italian "Flicker", is the instability of the light produced by the lamps.

The lamps are usually fed from the mains, with alternating current whose frequency is 50Hz (O 60 Hz in some countries). In these systems, the voltage varies from positive to negative 50 times per second and crosses zero twice per cycle.

Then the incandescent lamps, halogen or fluorescent (and even the LED if poorly designed), turn on and off a hundred times a second and produce light flickers at a frequency of 100 Hz (O 120 Hz).

Human beings do not consciously perceive one at frequencies greater than 50Hz flicker, but the receptors of light and the neurons of the brain are influenced. To which the flashing of the light sources, although invisible, It may also cause disorders and discomforts.


Health effects

Numerous studies have shown that flicker, although completely invisible to the human eye, It can cause headaches, eyestrain and nausea. Normally it is just a feeling of discomfort, but in some cases (sensitive subjects and prolonged exposure) visual acuity and overall health can be affected.

E’ has also been shown that if the work environment has lights that flicker workers get tired before and the production decreases. Women and children are more sensitive to these effects, Men and older people are less so.

A Gulet Black HeadPets are more sensitive to flicker us. Some of them, such as birds, see variations of light up to frequencies around 200 Hz, then ten times greater than what we see. For them a movie appears as a sequence of photographs. And some lamps may seem like strobe lights and be very annoying.



Types of lampsLamp Types

The incandescent and halogen lamps inevitably have an average high flicker (from 10% al 30%) and you can not reduce in any way.


The ancient neon tubes with passive feeder (an inductor built with many copper coils wound on iron) they flicker even higher (from 30% al 50%).



The fluorescent lamps CFL (Compact Fluorescent Lamp), also known as "energy-saving" have switching electronic ballasts. So theoretically could have flicker zero. In practice, however, due to space requirements and cost of all the CFL have an average high flicker, more or less equal to traditional fluorescent and halogen (from 10% al 30%).



The LED lamps are the only ones with a very low flicker (until the 0.1%). But if their supply is poorly designed can also flicker worse than any other lamp and get to touch the 100%.



safe values ​​for health

In these years (2017) there are integrated circuits specially designed to provide a current to the LEDs perfectly stabilized. These ICs are also very inexpensive and can work with power ranging from 85 a 265 volt, both 50 that 60 Hz.

Using these integrated, in a well-designed circuit, flicker is practically zero and the efficiency is maximum. With these integrated, and good quality LEDs, some manufacturers are able to overcome 100 lumen per watt.

There is therefore no reason to produce lamps that have a measurable flicker, except to save a few cents or cheating on efficiency data (some manufacturers take advantage of the confusion between the light peak power and average power consumed and produce lamps specially flickering in order to declare values ​​of lumens per watt very high).

Then, since it is possible to produce with zero flicker lamps, it makes no sense to do biological research, or arguing over them. The flicker value MUST be very low, virtually zero.

We think the only safe lighting is lighting that gives values:

  • lower 1.0% (with the method “Percent Flicker”)
  • lower 0.5% (with the "Flicker Index" correct and reported as a percentage)

Very low flicker
In this image you can see the measured values ​​of a Chinese led strip (60 LEDs per meter of the type 5050) Chinese fed with a stabilized power supply 12 volt, 5 ampere. Despite being cheap components, normally found on eBay, their flickering is practically zero.


commercial measuring equipmentCommercial Flicker Meter

The flickering of the lamps is measured with equipment called "Flicker Meter". This is a common name for systems that measure "irksomeness" Flicker. The values ​​measured by these units are calculated using standardized formulas. They are very precise equipment, certainly more precise than a device "DIY", and have only one flaw, costing an exaggeration. For example, what you see here on the right more than thirteen hundred dollars costs.

But actually we do not need all this precision. Soon we care to know if the value is 33.5% rather than 33.6%. And it also matters little to make mistakes, eg, from 20% al 30%. Because if there is flickering and is measured something beyond one percent, then the lamp is still unwrapped (the reason is explained in the previous chapter “safe values ​​for health”).

A gauge “do-it-yourself”

For many of us who are not plumbing is unthinkable to buy an expensive commercial unit. But fortunately we can build a great apparecchietto “do-it-yourself” with less than 10 euro (If we already have a Master and a tablet that we use to another).


For this project are only three components:

1) The usual form Master, we use in all projects thereminici.

2) A photo-transistor. They go pretty much all fine but if you have to buy it is advisable to choose a TEPT4400 or a TEPT5700 that have a high sensitivity and cylinders such as LEDs, they are comfortable to fix. Just make a hole 3 mm o da 5 mm plastic and insert them in the pressure.

3) A potentiometer 100 k ohm linear

Wiring diagram

With a potentiometer 100 k linear, It adapts the sensitivity to brightness to be measured.

Or you could use a single resistor 10 k.

In this case, to adjust the signal moves away or approaches the meter to the lamp until the application indicates that the signal is adequate.


This device could also be left bare with flying leads. But every time you use the wires would bow and end up breaking. So it's good to find him a little box to use as container.

It is not necessary that both a metal container. It could be a plastic box or wood, or only a lath open, on which to fix the master module and other components, so they will not move relative to one another.

The red and brown wires that go to the potentiometer are connected to one central and one on one side. If you are wrong side of the potentiometer it will work on the contrary (decrease the signal by turning it clockwise) if so, just weld the wire on the opposite side.

To secure the wires a bit of epoxy glass with six copper pads was used, glued to the box with a drop of cyano-acrylate glue (Attack). In place of this plate you could use a piece of a thousand-holes or even solder the wires to one another and then glue them to the bottom of the plastic.

The container used in this image is a “Teko_10011” which it is easily, Also on eBay. These containers are great for us to stay the Master and small circuits.

The finished appliance

On the left you see the USB socket, at the top of the knob of the adjustment and in the bottom right of the sensor potentiometer (a photo-transistor TEPT5700 which has the upper part nearly flat).

In this image the photo-transistor is inserted in a door-led, but the device will work equally well if you do a rough hole in the plastic and fixing the photo-transistor with a drop of glue.

The measurement software

To calculate the flicker values ​​using the application "Flicker Meter"

  • Download the application from this page.
  • You unzip the zip file in any folder on your computer.
  • It connects the USB cable and launch the application.

In order to easily launch the application it is good to link to "Theremino_FlickerMeter.exe" file to your desktop, or in the taskbar, or "start" box Windows 10.

During startup of the "Flicker_Meter" when you start your application "Theremino_HAL", that deals with the USB communication with the measuring device. Normally Theremino_HAL should launch minimized and close again by itself at the end. You need not change its parameters except in special cases.

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The instructions for use and other documentation and investigation files are downloaded from the same page from which you download the application "Flicker Meter".

Give at least look at files “Test lamps”, to see what the common lamps also flicker, we have always believed free of flickering.

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Greetings to all the friends of this great site.
A site based on friendship, where you get along and collaborate.

5 replies
  1. Poloverde
    Poloverde says:

    Interesting but the circuit that I only care about the potentiometer is the photodiode can not find the complete diagram with all the components used

    • theremino
      theremino says:

      The two schema components are connected to the Master Module.
      The connections are the orange wire, red and brown that you can clearly see in the picture.

      The Master module you take it as it is. E’ a bit’ like an Arduino but easier to use because no programming is necessary, It connects it to the USB and immediately works.

      So usually you consider the Master as a mouse and an oscilloscope and do not care to know the inside. However if you want to see the Master of the scheme can be found here:

      The Master can build it “do-it-yourself” but it also would need a PIC programmer and you might end up spending much more than to buy it. So usually you buy it on eBay or here:

  2. Poloverde
    Poloverde says:

    Interesting but as I outline just what the potentiometer connected or resistance of the photodiode is missing the complete scheme and the integrated use and other cpmponenti

  3. Just4Fun
    Just4Fun says:

    Interesting, I thought that the thermal inertia of tungsten lamps made them practically immune to flickering… Hmmm…
    If one day I have time (What now unlikely… 🙂 ) I want to do testing.


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