I would like to know if anyone has tried to use a phototube with arduino. I want to use it to demonstrate the photoelectric effect. Could anyone help me out? Has someone done anything similar? I was thinking in models such as A59RX or RCA 1P39/929, but these are difficult to find in Europe...
All you need to demonstrate the photoelectric effect with a phototube is a voltage source and a meter capable of measuring a few microAmperes of current.
The 1P39 will work very well with as little as 9V (PP3 battery) connected across the anode and cathode.
Here is my 1P39 "retro" light meter, measuring indirect daylight:
Since an Arduino can't directly measure current, you could use an analog input to read the voltage across a load resistor. 50K*100uA = 5V.
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Then why do you want to use them?
You can use a plain old LED to demonstrate the effect.
I need this for a project that I've chosen to do during summer. My main problem is how to obtain the phototube, I've been struggling to find the models RCA 1P39 and 929 (which I've found that are the best for this kind of experiment). How did you buy yours? Is there any web where I can find those? If not, what alternatives do I have? What do you think about the RCA 922 (works with red/IR light)? On the other hand, I think that this phototube must be connected by welding it. Thank you? Do you know which other things may I need?
Cheap and simple LED.
But LEDs don't show the photoelectric effect. I could only use LEDs as a light source. I want to measure how the different wavelenghts affect the voltage of the circuit. Therefore I need a phototube.
Oh yes they do. You can show everyone how smart you are by explaining how an LED will also act as a photodiode.
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Photodiodes and LED's aren't the same thing.
No but both can be used to demonstrate the photoelectric effect.
They use a semiconductor as a cathode, not a metal. For this reason, there isn't a work function of the material in the cathode (as it hapens in the photoelectric effect that has methal made cathodes). Furthermore, photodiodes use the photovoltaic effect, that is similar to the photoelectric effect, but not exactly the same. Could you specify your idea?
No everybody makes that distinction and strictly speaking you are correct
So forget I mentioned the LED.
This author uses a vacuum tube rectifier ( in this case 2X2A ) as a demonstration phototube. You may have more success searching for a suitable rectifier tube.
A very interesting topic by the way.
You can get this in Europe new for about 5 Euro but I can't say if you can use it for your intended purpose:
Thank you for your interest. I'm thinking in photodiodes as an alternative if I don't find a phototube.
But as you said they do not demonstrate the photoelectric effect but instead the photovoltaic effect.
I don't know if that tube could work out, because I don't know what "rectifires" tubes are. Do you know something about these that could be useful to my project?
Try reading the entire post before you comment, then you would know!
I can't say if this particular rectifier tube can be used as a substitute for a phototube. All I know is what is written in the quoted article where another model of a rectifier tube is used to demonstrate the photoelectric effect. What I can say, though, is that it is that it is astoundingly cheap for a new vacuum tube.
Yes, it is extremely irritating when a thread is cluttered up with barely relevant AI generated text.
Hopefully it will be gone soon since I have reported it as spam.
Most rectifier tubes I remember have the anode completely surrounding the cathode, that could make it difficult to get light to strike the cathode-facing surface.
The material the glass is made of could also have a major effect, if the experiment involves a specific frequency of light.
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Good points. The 2X2A, which was mentioned, is rather special. : HV rectifier for CRT and radar power supplies. 12.5KV PIV at 7.5mA. So may have a more open construction.
2X2A, Tube 2X2A; Röhre 2X2A ID4272, Half-Wave Vacuum Rectifi | Radiomuseum.org :
