Photomultiplier Tubes camera build

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Photomultiplier Tubes camera build

Postby Harry Dalek » Tue Jul 19, 2016 6:32 pm

I got a few Photo-multiplier Tubes off ebay this week from a local seller (For sale are six photo-multiplier tubes from the mid eighties that have been sitting in a dark box for the last thirty years or so.)
They were really all for the price of one so if one works thats fine .
i have been reviewing past posts on the forum from others that had been trying them and asking advice ,so reading what i have so far i can see they need to be handled with care .
I have found some information on 2 which are the same tube EMI 9524
The others no luck from a quick search
EMI 92521

EMI D151B

Hamamatsu R1282

RCA 77-52(6199)

I have been thinking on the small steps approach as in a safe test when i know enough to hook one up don't want to brake them.
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Last edited by Harry Dalek on Sat Sep 10, 2016 2:38 pm, edited 1 time in total.
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Photomultiplier Tubes

Postby Steve Anderson » Tue Jul 19, 2016 6:51 pm

Though others may disagree with me here, basically DO NOT have any bright light and volts applied to the tube at the same time. By bright I mean the average daytime illumination inside the average household. In fact I suggest far less than that, a clear nighttime sky with a full moon can destroy these devices. Of course it varies.

I'm not sure why someone stuck the black tape to the tubes. Not needed. But to get the lowest 'dark current' they do need a while to adapt but no harm is done. After 30-odd years the dark current will be quite high anyway, but no problem. It will bleed away under bias after a few minutes - less than an hour anyway. If the tube is used every few months you won't notice it.

My experience with 931A's though has been somewhat disappointing. I found them very sensitive, sure, but at the same time really noisy. In fact useless. These things have been used in the past for decades and with good results, so I can only assume that those I purchased were sub-standard and/or defective. They were cheap though.

A case of, "You get what you pay for."

Steve A.
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Re: Photomultiplier Tubes

Postby Harry Dalek » Tue Jul 19, 2016 7:17 pm

Steve Anderson wrote:Though others may disagree with me here, basically DO NOT have any bright light and volts applied to the tube at the same time. By bright I mean the average daytime illumination inside the average household. In fact I suggest far less than that, a clear nighttime sky with a full moon can destroy these devices. Of course it varies.

My experience with 931A's has been somewhat disappointing. I found them very sensitive, sure, but at the same time really noisy. In fact useless. These things have been used in the past for decades and with good results, so I can only assume that those I purchased were sub-standard and/or defective. They were cheap though.

A case of, "You get what you pay for."

Steve A.


I had been reading your advice on PMT's from past posts Steve i can see you need to take care the ones i won on ebay have the light sensitive area covered by tape can they be damaged while not powered up ? ..i have always been curious about these things and i might or might not be lucky with what i got but as you say never know unless you try .
Still need to do some research on them ...would need to test them safe at some stage ..would be nice to do a camera idea in the future but i know little steps get you there ..i was thinking a simple goal might be be a transmitting led at low light levels at a distance to it ,night test if room light is enough to destroy them .
Even perhaps just picking my nbtv monitor just thinking of ideas i don't even know yet if these things need optics .
Need some sort of test to know its working that is safe,
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EMI 9524.png
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Re: Photomultiplier Tubes

Postby Steve Anderson » Tue Jul 19, 2016 8:49 pm

Harry Dalek wrote:..I can see you need to take care, the ones i won on ebay have the light sensitive area covered by tape can they be damaged while not powered up ?

Nope, they're fine as long as they don't have a lot (it varies) of light and volts applied to them at the same time. You can quite safely remove the black tape when there is no volts on the tube. Whoever sold them was obviously unaware of this.

When I say, "A lot of light", think of of a power cut in the middle of the night and no flashlights - that's still a lot of light to these devices.

Remember, these devices are generally blue-sensitive whereas Silicon is red and IR sensitive. I had a blue LED modulated by a really low current (microamps) to test the 931s. The current was so low I couldn't even see the light from the LED after some 15 minutes of my eyes becoming dark adapted. But the PMT sure did! It was actually quite hard to keep out the minuscule amount of street-lighting!

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Re: Photomultiplier Tubes

Postby Harry Dalek » Tue Jul 19, 2016 10:11 pm

Steve Anderson wrote:
Harry Dalek wrote:..I can see you need to take care, the ones i won on ebay have the light sensitive area covered by tape can they be damaged while not powered up ?

Nope, they're fine as long as they don't have a lot (it varies) of light and volts applied to them at the same time. You can quite safely remove the black tape when there is no volts on the tube. Whoever sold them was obviously unaware of this.

When I say, "A lot of light", think of of a power cut in the middle of the night and no flashlights - that's still a lot of light to these devices.

Remember, these devices are generally blue-sensitive whereas Silicon is red and IR sensitive. I had a blue LED modulated by a really low current (microamps) to test the 931s. The current was so low I couldn't even see the light from the LED after some 15 minutes of my eyes becoming dark adapted. But the PMT sure did! It was actually quite hard to keep out the minuscule amount of street-lighting!

Steve A.


HI Steve i have been looking at your experiments on PMT General Discussion so reading up what you got up to ,have not finished but very interesting i never really looked into PM tubes always interested me but getting my hands on one not so easy .
If they are blue sensitive wonder it that go's up to uv...any case a frequency sweep test is more logical but these things work up to the MHZ range but seeing it work with that might be a good first step ...i will do more reading BTW i like your circuits for the tube you used .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Photomultiplier Tubes

Postby Steve Anderson » Wed Jul 20, 2016 2:53 pm

Generally PMTs have a response to modulated light into the several hundred of Mhz region. Those developed for nuclear applications (scintillation etc.) go well into the GHz frequencies.

Response to the colour of light and UV varies depending on the coating applied to the cathode and the type of glass used for the tube proper. The datasheet for each type will cover this.

The datasheet often will include a suggested circuit, after a while you'll see that they're all quite similar. I did upload the Burle and Hamatsu handbooks somewhere in the PMT thread but if you can't find them they're here again. Good bedtime reading!

Steve A.
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Re: Photomultiplier Tubes

Postby Harry Dalek » Wed Jul 20, 2016 8:18 pm

Steve Anderson wrote:Generally PMTs have a response to modulated light into the several hundred of Mhz region. Those developed for nuclear applications (scintillation etc.) go well into the GHz frequencies.

Response to the colour of light and UV varies depending on the coating applied to the cathode and the type of glass used for the tube proper. The datasheet for each type will cover this.

The datasheet often will include a suggested circuit, after a while you'll see that they're all quite similar. I did upload the Burle and Hamatsu handbooks somewhere in the PMT thread but if you can't find them they're here again. Good bedtime reading!

Steve A.


Thanks Steve for the uploads i will do some reading ... i did find data on another the 6199 mines an RCA so not sure if this is the same so thats good half of them now if it is,as you say theres a circuit and such on the data sheet ....
I have not seen enough of them yet to see how similar the tubes are to each other and there power supply and such ,i like having the data sheet other wise you are working blind ,its just a pain trying to track them down .
I am going to have a look at the 931 data sheet below every one seemed to be using in past post on the forum and see what is similar and what is not ...the light sensitive window is on the side of these things ? all mine are at the top .
Could you have used a white light led for your tests ? know its not as good but blues mixed in there .
BTW also i did giggle at the foil thing enough said !
Attachments
6199.pdf
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hell-zetfax-931A.pdf
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Photomultiplier Tubes

Postby Steve Anderson » Wed Jul 20, 2016 8:44 pm

Yes, I could have used white LEDs, but at that time I probably didn't have any handy. Plus the yellow output of white LEDs is generated from the UV excitation of a phosphor which can be quite slow in response time. Though the PMT shouldn't much respond to it, why throw another potential variable into the equation? White LEDs are marginal even for NBTV, they may get better with time but generally white LEDs are used in flashlights and other simple devices where human eyesight is involved - and that's not particularly fast.

If you want white light use an RGB LED, all three chips in one package, as fast as any other LED, no phosphor invovled and you can make it any colour you wish. Costs more as you'd expect.

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Re: Photomultiplier Tubes

Postby Klaas Robers » Thu Jul 21, 2016 6:04 pm

Steve, talking about RGB LEDs.....:
last few weeks Chis Lewis "finished" his colour NBTV monitor. Het used 3 RGB LEds behind the Nipkow disc. The strange thing is that when feeding the 3 chains with the same current, they emitted white light.........
A few years ago I did an experiment with 3 separate LEDs one R one G and one B, the same size, the same outine and the same make, and when I feeded them with the same current the light wasn't white at all, it was a kind of cyan. I had to adjust the currents to
- 200 mA for Red
- 70 mA for Green
- 40 mA for Blue
to get white light.
So I circuited two Red LEDs in series to get the current for Red to 100 mA.

This is not so strange, we could even expect it, as,
- suppose that the LEDs have a 100% efficiency, there is one photon for each electron.... yes?
- but the energy in a photon is dependant of the wavelength,
- Blue has more energy than Red.
- That is also the reason that the voltage over a Blue LED is higer than over a Red LED,
- so at the same current more power ( V x I ) is going into the Blue LED
- and less into the Red LED.
- ...... yes?
This is well in line with the first RGB LED-lamp, the "Living Colors" of Philips, in which there are two Red LEDs and one Green and one Blue LED. I have that lamp.... two of them. An archetype and almost history

But now: How is it possible that from an RGB LED the emitted light is white when we send the same current through the 3 LEDs? Have they spoiled the efficiency of the Green LED by a factor 2.8 and of the Blue LED by a factor 5 from what practically is possible? I see in the documentation that Chris sent me that the voltages over the LEDs differ not that much, that they circuited internally two Red LEDs in series.
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Re: Photomultiplier Tubes

Postby Harry Dalek » Thu Jul 21, 2016 9:02 pm

I ended up getting some 3 colour leds some time back talking about them here i have to check out what the hell i have done with them ...

I was looking at my RCA 6199 PMT it looks pretty much what i have data for which is good .

Looking at what this thing is sensitive to the data does say 400nm positive negative 30nm which is pretty much ultraviolet,i suppose its still useful just stuck with seeing only this end of the spectrum..i do happen to have a lot of uv leds and such ...

Have to look into the EMI 9524 tube if i can find out any thing on that one i have 2 of that one.

I came across some work on PMT's by the late great Peter Yanczer on a PMT flying spot camera .

http://www.earlytelevision.org/fss_camera.html

He had a flying spot and direct pick up version .

Also reviewing past posts here on Steve O Colour PMT camera with Steve A input great work ! missed all that at the time glad the forum is a place to review all this great work .
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Photomultiplier Tubes

Postby Steve Anderson » Thu Jul 21, 2016 9:38 pm

Blue generally is the longest wavelength response you're going to get out of a PMT. There are a few that are to a limited degree are sensitive to green and/or red as used by Steve O, but these are not easy to come by. ergo expensive.

To find a PMT that is Panchomatic, as per the monochrome camera film is most unlikely. B&W camera film started out with the same problem, a really heavy bias toward one end of the spectrum which is why some early monochrome photos look kinda weird. Years of development later and Ilford launched arguably the best mono still camera film ever, Pan-F.

Anyway, Silicon is red-IR centric, PMTs, blue-UV. That's just the way things are.

Cadmium Sulphide (CdS, i.e. LDRs) are green sensitive, but just too slow for anything here.

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Re: Photomultiplier Tubes

Postby Klaas Robers » Thu Jul 21, 2016 9:56 pm

Harry, it depends on what you want to do with it. If you want to use it for an NBTV camera, you will experience reasonable video out of it, however blue colours ar brighter than red colours, while green is in the middle. In one of the documents sent above you can see the sensitivity curve, which is indeed maximal at blue / violett and almost zero at red, 650 nM (6500 Angstrom). We recognize this very well, when it is really dark. Our eyes then move to black and white viewing, where also blue is the brightest and red almost black. So this is something natural. You even don't realise it.

Happily there is a remedy: place a colour filter between the Nipkov disc and your PMT. That filter should suppress blue, so a yellow filter. These are well known from the time of black and white photography. The original "Ortho chromatic" chemical film is also most sensitive for blue and almost not for red. When taking a picture of a landscape with a blue sky, this sky became bright white and most clouds disappeared. A yellow filter on the lens cured this. So those yellow filters might be laying around next to older cameras. There are several types, try which you like best.

And yes, this filter makes your camera less sensitive. A factor of 2 or 3 is normal. This is written on the ring of the filter. So: nothing new.
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Re: Photomultiplier Tubes

Postby Harry Dalek » Thu Jul 21, 2016 11:20 pm

Thanks Steve and klass your replies there being new to these things just reading and picking up your advice and where ever i find it, the newsletters are good to for past cameras using them ,a camera would be interesting a goal one day for sure but little steps i must tread first before i give that a go but for sure a nbtv or slow scan camera would be nice use for the tubes .
As Steve mentioned the tubes are pretty similar a Question i have to ask would different PMT's pretty must work to some degree in the same circuits with the same pin connections ?
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: Photomultiplier Tubes

Postby Steve Anderson » Fri Jul 22, 2016 2:50 pm

As always it's best to refer to each devices datasheet. As a generic species they all generally operate in the same manner, just like transistors as a generalization work in the same way. But each version has different limits and often geared towards a particular application, RF pre-amps, audio output and so on...

The 931A PMT could be said to be the BC107 of PMT's, it's a general-purpose device and finds a home almost anywhere. But if you want hundreds of megahertz a BC107 is not the device of choice. If you want the most sensitivity or lowest noise the 931A wouldn't be the PMT you'd choose.

So study the datasheets, if you're not sure about something, just ask. Hopefully someone here will be able to help.

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Re: Photomultiplier Tubes

Postby Harry Dalek » Fri Jul 22, 2016 9:19 pm

Steve Anderson wrote:As always it's best to refer to each devices datasheet. As a generic species they all generally operate in the same manner, just like transistors as a generalization work in the same way. But each version has different limits and often geared towards a particular application, RF pre-amps, audio output and so on...

The 931A PMT could be said to be the BC107 of PMT's, it's a general-purpose device and finds a home almost anywhere. But if you want hundreds of megahertz a BC107 is not the device of choice. If you want the most sensitivity or lowest noise the 931A wouldn't be the PMT you'd choose.

So study the datasheets, if you're not sure about something, just ask. Hopefully someone here will be able to help.

Steve A.


Yes i am nervous to try a tube without knowing its voltage range or a circuit example ,they look to be around the same main power supply range but how thats adjusted to the dynodes would be the problem on an unknown pmt.

I am looking at the 931 to my RCA 6199 via the data sheets i have they are not identical but very close .

The 2 examples below give 2 different part values for these 2 circuits ,i think the first looks like what i am looking for as to our hobby ?

Another Question to any one how has used these or knows the resistors caps for the tubes dynodes are wired close as possible to thed tubes connections ? it reminds me of photo diode transistor no long wires between it and the head amp so i suppose this is the same best go close as possible for the head amp as well if that is needed at all for a PMT ?
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RCA 6199
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931
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The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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