Ingenious hybrid lamp sold in a MINDLESS way...

Can a light bulb be both incandescent and gas-discharge? The little, odd GTL3 lamp seems to be a hybrid between the two technologies. In this video, I take a closer look at the science hiding inside it.
The lamp is sold in two different versions online. Only one of them can be recommended - I show you why!

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#UVC #GTL3 #Brainiac75

[SeanBZA]

I actually met those a long time ago, as they have been used at least since WWII as map lights on aircraft, with the tube having a phosphor coating to create white light, then a switchable filter, so that you can either filter out all but the red phosphor emission, to keep night vision, or have some of the UV light bleed out as well, to illuminate maps that have invisible ink marking on them, put there so that if they were discovered there would be no intelligence immediately visible. Run off the 28V DC bus using a pair of resistors, and then a variable resistor that functioned both as power switch and display brightness control in the feed to the lamp. IIRC 27R 15W main resistor, then a 60R 5W resistor across the lamp to limit the voltage when the main filament went open, so it would not self light, and then a 20R 20W wirewound brightness control with a switch. Switch and brightness control on the lamp itself, on the end of a curly cable so you could use it close to the map. Resistor mounted at the other end, providing a bit of heat extra to the cockpit all the time, and not noticed in the other power draws off the battery when the aircraft is on.

[ooddrrhh]

Seeing the graph that shows how much UV-C is produced compared to the visible light is terrifying because I'm a welder and the visible arc alone is blinding. I would love to know how much UV light is produced! I also use roughly 28 volts and 350 amps. A wee bit more than a 3w light bulb!

[izzieb]

I can't really add anything intelligent, but I always like seeing a notification for a new video from you. Always something interesting and often learn something new.

[wimwiddershins]

If UVC was visible to the human eye that lamp would be super bright and painful to look at. Instead, we can happily stare at it while our retina gets a suntan. :/

[sulfie]

Super informative and intriguing video! Watching the lamp switch the light emitting filling was incredible!

[n-steam]

I wouldn't call it a hybrid, I'd call it a half-fluorescent.
Those long tubes have similar heating elements on either side with small voltage differences, and a large voltage difference between either end.
They also contain the same mercury too and emit UVC, you're saved by the phosphor coating that absorbs the UVC and re-emits it as visible light.

[madbstard]

I have a few of the 240v bulbs....well, kinda similar to these. Used to use them for a quick sterilization of repaired computer equipment. But always used them with wifi plugs cos thanks to BigClive, I know that UVC can be a bit worrying.

[rpavlik]

You could use a photodiode and an oscilloscope to view the oscillating of the light in the DC version.

[KekTekDe]

2:35 would be interesting to know if the thermoionic coating is also radioactive (since strontium oxide or barium seem common)

[chrisdickens]

Fascinating to see the ratio of UVC produced vs visible light.

[zebo-the-fat]

I run one of these from a 12 volt transformer with a series high wattage resistor to limit the current. Works well for de oderising old walking boots!

[sulfie]

Good thing my midterm class starts in 10 minutes! So excited for this video!

[poorlydrawnstickman]

I love the scientific approach and the confirmation of your guesses in all of your videos! Keep it up, can't wait for your next video!

[pada]

The music and that slow-mo shot give me vintage sci-fi vibes and I love it.

[garygough]

Twice the value of ballast cap works for 120 VAC .
Related accident. I have a old incandescent bulb that radiates 70 MHz pulses when on. My guess is the folded filament self resonance is about 70 MHz, the bulb may be gassy and the filament ends and support wires are alternating forward biased diodes ( noise emitting).

[martine-e-dee]

Thank you for unveiling those hidden gems of science for us!

[TonnyCassidy]

played around with the same bulb a while ago, that ballast, aside from changing the DC to AC also increases the voltage, the bulb requires about 24v to start heating the filament, the 10v written there is only after it strikes therwise it needed a current limited 24v supply, i managed to power mine off dc PSU with an H-bridge, PSU set to 25v 300mA and with an oscillator to make the H-bridge switch at around 2.3KHz increasing the freq dims the bulb

also did a banana test which didnt work for some reason, i did verify the banana test should work if it really produces UVC by doing the same test with philips TUV lamp

[collectorguy]

This nicely demonstrates the very high electrical conductivity of plasma. Always fascinating.

[kakarikiIck]

Omg how dangerous. People don’t care if they sell a load of the bulbs online. Thanks for educating people.

[user]

04:59 That sucks. I still remember what 310v from full 3µF capacitor felt. That can be even worse.