UV generator based on a spark gap

v4000ds · Mar 22, 2021

I want to make an ultraviolet generator based on a spark gap in air. I tried using a drill motor as this.
To do this, I covered the contacts on the commutator with a marker to make the contact worse. Supplied 19.8 V from laptop charging, serial connection of electromagnets with rotor windings, 15 ohms. The current was about 1A.
After about 20 minutes of rotation of the engine, the brushes were worn off.

Instead of carbon brushes, I started using copper wires, they burn out faster, but give a larger spark.
I get even more spark using tin soldering wire.
My question is what can be used to cover the commutator and which brushes (tin, copper, etc) should be used to generate the largest spark?

rjenkinsgb · Mar 22, 2021

Anything that is sparking is burning away.

Why not just make a carbon arc type source? They are simple and emit large quantities of UV, plus carbon rods are cheap.

You can use a solenoid with a small number of turns of heavy wire in series with the arc setup to pull one of the rods away from the other and regulate the current.

Edit - examples:

Carbon Arc Rods 6.4mm x 305mm 5 off | eBay

6.4mm x 305mm. General purpose carbon arc rods.

www.ebay.co.uk

2 x Graphite Carbon Rods for Science Experiments Electrodes | eBay

Still fits through a standard letter box. Various sizes available in drop-down option above all x 100mm. (length approx.).

www.ebay.co.uk

**broken link removed**

audioguru · Mar 22, 2021

Why are you making UV? To blind and burn the skin off somebody?

v4000ds · Mar 23, 2021

rjenkinsgb said:
Why not just make a carbon arc type source? They are simple and emit large quantities of UV, plus carbon rods are cheap.

Because my parents won't let me buy carbon electrodes. In Ukraine 1 kg of a carbon electrode costs $ 2-3. I have a lot of copper and tin, I don’t need to buy it. Not long ago I started doing electroplating.
I have different metals (in the composition of salts, substances) - iron (transformers), aluminum (radiators), copper (wires), mangan&zinc (ferrites), barium (in copper wires), strontium (ferrites), tantalum (capacitor), titanium (hdd), zirconium (radio tubes), magnesium (hdd), neodymium&nickel (magnets), sodium (NaCl), potassium (KOH capacitors, batteries), lithium (Li-ion accumulators ), silver (CDs, relays), gold&platinum (radio parts). I can cover the commutator with anything.
I want to do fluorescence microscopy. My parents do not want to buy me a ready-made ultraviolet source (lamp, LED), so I have to do it myself. The most accessible option for me - from the motor from the drill.
In addition to receiving sparks on brushes, it is possible from the motor a pulse source of high voltage. To do this, connect the brushes in series with the diode, and put the diode and capacitor in the opposite direction. I will probably make such an option.

audioguru · Mar 23, 2021

Maybe the parents of the kid smartly did not want him to buy things for him to go blind and burn his skin.

Pommie · Mar 24, 2021

Sometimes when I weld and it's a small job, I just do it quickly without gloves. Every time, my (left) hand gets sever sunburn. Arcs give out a lot of UV.

Do you have a welder?

Mike.

MacIntoshCZ · Mar 24, 2021

Which wavelenght do you want?

Pommie · Mar 24, 2021

MacIntoshCZ said:
Which wavelenght do you want?

If it's a spark gap, all of them.

Mike.

MacIntoshCZ · Mar 24, 2021

Pommie said:
If it's a spark gap, all of them.

Mike.

" I want to do fluorescence microscopy. My parents do not want to buy me a ready-made ultraviolet source (lamp, LED), so I have to do it myself "
He will need to filter it to get exact wavelenght.
I have zero knowledge in this. I dont think excitation filter is adjustable. Or is it? He will need to swap it to change wavelenght i think

v4000ds · Mar 24, 2021

I also have zero knowledge in this .
But the scheme is wrong. The glass microscope absorbs ultraviolet light.

Fluorescence - Wikipedia

en.wikipedia.org

The most striking example of fluorescence occurs when the absorbed radiation is in the ultraviolet region of the spectrum, and thus invisible to the human eye, while the emitted light is in the visible region, which gives the fluorescent substance a distinct color that can be seen only when exposed to UV light.

Ultraviolet - Wikipedia

en.wikipedia.org

Name Abbreviation Wavelength
(nm) Photon energy
(eV, aJ) Notes/alternative names
Ultraviolet C UVC 100–280 4.43–12.4,
0.710–1.987 Short-wave, germicidal, completely absorbed by the ozone layer and atmosphere: hard UV.
Ultraviolet B UVB 280–315 3.94–4.43,
0.631–0.710 Medium-wave, mostly absorbed by the ozone layer: intermediate UV; Dorno [de] radiation.
Ultraviolet A UVA 315–400 3.10–3.94,
0.497–0.631 Long-wave, black light, not absorbed by the ozone layer: soft UV.

Extreme ultraviolet EUV 10–121 10.25–124,
1.642–19.867 Entirely ionizing radiation by some definitions; completely absorbed by the atmosphere.
Vacuum ultraviolet VUV 10–200 6.20–124,
0.993–19.867 Strongly absorbed by atmospheric oxygen, though 150–200 nm wavelengths can propagate through nitrogen.

Arc lamp - Wikipedia

en.wikipedia.org

MacIntoshCZ · Mar 24, 2021

v4000ds said:
I also have zero knowledge in this .
But the scheme is wrong. The glass microscope absorbs ultraviolet light.

Fluorescence - Wikipedia

en.wikipedia.org

Ultraviolet - Wikipedia

en.wikipedia.org

Arc lamp - Wikipedia

en.wikipedia.org

View attachment 130530

thanks

v4000ds · Mar 24, 2021

http://www.sciencedirect.com/topics/engineering/carbon-arc

ZEISS Microscopy Online Campus | Mercury Arc Lamps

Mercury arc discharge illumination sources are highly reliable, produce very high flux densities, and have historically been widely used in fluorescence microscopy.

zeiss-campus.magnet.fsu.edu

v4000ds · Mar 24, 2021

Maybe I need a special ultraviolet microscope made of special glass,

Fluorescence microscope - Wikipedia

en.wikipedia.org

but I use a cheap glass

Pommie · Mar 24, 2021

You can't see uv which is why you use a fluorescent dye, so it gets converted to a wavelength you can see.

Mike.

Name	Abbreviation	Wavelength (nm)	Photon energy (eV, aJ)	Notes/alternative names
Ultraviolet C	UVC	100–280	4.43–12.4, 0.710–1.987	Short-wave, germicidal, completely absorbed by the ozone layer and atmosphere: hard UV.
Ultraviolet B	UVB	280–315	3.94–4.43, 0.631–0.710	Medium-wave, mostly absorbed by the ozone layer: intermediate UV; Dorno [de] radiation.
Ultraviolet A	UVA	315–400	3.10–3.94, 0.497–0.631	Long-wave, black light, not absorbed by the ozone layer: soft UV.

Extreme ultraviolet	EUV	10–121	10.25–124, 1.642–19.867	Entirely ionizing radiation by some definitions; completely absorbed by the atmosphere.
Vacuum ultraviolet	VUV	10–200	6.20–124, 0.993–19.867	Strongly absorbed by atmospheric oxygen, though 150–200 nm wavelengths can propagate through nitrogen.

UV generator based on a spark gap

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