House of Hacks

Friday, February 26, 2016

How to measure fluorescent and LED light flicker


Fluorescent tubes flicker because of their inherent design. LED lights may or may not flicker depending on how well their power supply is designed. How do you measure the amount of flicker? In this episode, we quantify the flicker in the fluorescent tubes and after an LED light conversion.

How to easily convert fluorescent tubes to LEDs:
Electronupdate video: Measuring Light Bulb Flicker with Nothing More Than a Cell Phone:

For a written transcript, go to How to measure fluorescent and LED light flicker

Music under Creative Commons License By Attribution 3.0.
Intro/Exit: "Hot Swing" by Kevin MacLeod at


After seeing last week's episode about converting fluorescent lights to LEDs, David Terry asked "do they flicker the same way fluorescent tubes do?” I wasn’t sure, so let's measure and find out, today at the House of Hacks.


Hi Makers, Builders and Do-it-yourselfers. Harley here.

Fluorescent tubes are powered by AC current and flicker based on the speed of the power cycles. Here in the United States, our power cycles at 60 hertz. This means the hot lead varies between positive voltage and negative voltage 60 times a second. The tubes don’t really care about positive or negative values, just the absolute value and so will flicker at twice that rate, or 120 times a second.

This is too fast to bother most people, but a non-trivial segment of the population are affected by this and have problems working under fluorescent lights. The flicker can also cause artifacts when shooting video at certain frame rates. And, as the bulbs age, they may not go on and off at every cycle, causing the flicker to slow down and become more noticeable.

To measure the flicker, I've got this simple setup. I have just a solar cell and the oscilloscope. The flicker in the lights will cause the output of the solar cell to oscillate in sync and the scope allows us to see that variation. At 120 times a second, we expect to see each cycle to be around 8 milliseconds so I have the scope set to 10 ms per division.

Now I'm going to connect the scope to the scope to the solar panel. And we’ll see what we have here… and that's exactly what we expect to see; each cycle is about 8 milliseconds.

So now I'll go over into the room other room and check it out with the LEDs.

I still have exactly the same setup as I had before. Let’s connect the scope to the solar panel and see what we get.

Ah, a straight line. So, to answer David’s question: no, there is no flicker with these LEDs. Thanks David for asking the question.

And coincidentally, a couple days ago an electronics channel I subscribe to, electronupdate, uploaded a video showing how you can use a cell phone to detect this flicker. I thought you might find that interesting.

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Thanks for joining me on our creative journey. Now, go make something. It doesn’t have to be perfect, just have fun!

Friday, February 19, 2016

How to easily convert fluorescent tubes to LEDs


There are several ways to convert a fluorescent tube fixture to using LED lights. In this episode, Harley shows the fastest, easiest, but most expensive option to retrofit T8 and T12 fluorescent lights to LEDs. At the end, measurements are taken of the light output to see the effect of the new lights.

How to count in binary:

For a written transcript, go to How to easily convert fluorescent tubes to LEDs

Music under Creative Commons License By Attribution 3.0.
Intro/Exit: "Hot Swing" by Kevin MacLeod at


Today at the House of Hacks we’re going to go from this to this. Oh, yeah!

Hi Makers, Builders and Do-it-yourselfers. Harley here.

The general illumination in my shop is all fluorescent lights and for quite some time now I’ve been wanting to upgrade them to LEDs. Recently I’ve had two bulbs that were kind of on the way of going out and today they just didn’t come on at all. So I went down to the home store and decided to bite the bullet and convert a couple of my fixtures, two of the fixtures, a total of four bulbs, from fluorescent to LED.

In all my investigation I’ve found that there are kind of three principal ways of doing this conversion: the first is very quick, very easy and expensive, the second is less expensive and also a little bit more work, and the third way is the most amount of work but also the least expensive. So, today, because of time pressure, I decided to go, on these, with the first option of the most expensive but the fastest and easiest to do.

For cost comparison, these bulbs are $60 apiece and I have four bulbs to replace. So that means the total cost on this conversion today was $240. Now to put it in perspective, I think I paid $200 for the whole fixtures originally, including fluorescent tubes. So it is quite a bit more expensive but now I have LED lighting with all the benefits thereof.

Today I want to look at what it takes to install them and what the difference is in the light output. So let’s get to it.

These come in four foot long packages. There’s two tubes that snap together to make an eight foot section. They’re made by Feit Electric, Feit electric, I don’t know how you really pronounce that. They replace both T8 and T12 bulbs and the advantage of these is they work off the ballast voltages so you have to do is take out the old bulb and replace it with the new one after you put everything together and unpackaged it.

It says it’s rated for up to 50,000 hours of life. We’ll see how that actually works itself out. It uses 44 watts and has a color temperature of 4100 Kelvin. So it’s sort of in the middle of the color temperature range.

Here we have one set of ends as packed. A cap is over one piece for shipping to cover the open middle where the two pieces will be joined together. It can be removed and discarded. And the other end contains the power pin that will connect to the light fixture.

Here’s the other set of ends. One end has a clear plastic piece over it that contains a magnet. This will stabilize the center of the light. Remove it for now and set it aside. This is the other pin that will connect to the light fixture. The other piece has a connector with two spring loaded pins. Pull this out until the pin locks into place.

Now slide the clear plastic support over the end without the connector but don’t cover the small hole for the locking pin. Slide the two pieces together until the pin locks into place. Finally slide the plastic piece over the joint to help support the connection.

We can see half the tube is aluminum extrusion to provide support and heat dissipation. The other half has a curved frosted diffuser.

Installation is just like a normal fluorescent tube. Once both ends are in place, push the middle up so the magnet sticks to the fixture for support.

And that’s really all there is to it. Snap the two pieces together, take out the old bulbs and put in the new bulbs. Short. Sweet. Simple.

I really like it. It seems to work out really well.

Now let’s go take a look at what the actual light output is.

The measurement of tubes is on the left and the LEDs on the right. There is 1 EV difference between the two. In photographic terms this is one stop, or twice the amount of light out of the LEDs.

So you can see, the light output from these is quite a bit more. It’ll be nice having consistent color temperature across all my bulbs too. Working in the shop should be much more pleasant for me.

If this is your first time here: Welcome! We're glad you’re here. All my videos have to do with maker related types of topics: woodworking, metal working, shop projects in general, kind of like this. If that kind of thing sounds interesting to you, go ahead and subscribe. We’d love to see you again in the next video.

Now, go make something. It doesn’t have to be perfect, just have fun!