New Project.

Hello gadget fans! Captain Demotricus Tiberius Berk at the helm again, and today I`m starting a new project.This time its a little removed from PCs but WILL have a Web Cam built in to it so I`m posting it.I`m going to make a Star-Scope (or a “Long Range Visible Sensor Array” to keep in with the naff Star Trek associations).

This will be whats known as a 1st Generation device, and as such, is quite old technology.
I`ve managed to source a very cheap supplier of Ex military Hardware and amongst the goodies that they sell is a “Cascade Tube Image Intensifier”. This is a unit that was originally used in the British Challenger tanks, -its a P8079HP Cascade Tube with a self contained power supply unit and can be run off a 3-7 volt supply, so either a six volt battery pack (4 x AA size) or a 5 volt USB supply rail will power the device.
Physically the unit is a long thick and massy Tube about 5 inches diameter by 15-20 inches length with a phosphor display screen at one end and an input sensor at the other. To make it work you need two lenses, an objective lens , to project a focused image onto the input sensor, and an eyepiece or magnifying lens to view and magnify the output screen. In practice , a 35mm Camera lens of the highest F rating you can find (more light = better performance) will work as an objective lens. -You have the same choices as you do with a camera – either a wide angle (30-50mm), a fixed 1:1 ratio lens (50mm) or a telephoto lens will work, but the field of view will be smaller for longer lenses and the smaller the field of view, the less light will be gathered.Most commercially available night sights (gen 1) will amplify light by about 100 times. a good gen 1+ will give you 300 times the light. Gen 2 will give you between 5000 and 10,000 times the light.
A Gen 3 will give you between 20,000 and 80,000 times.

Gen 4s are classified.

THIS unit will give you 50,000 to 100,000 times the light so is extremely useful.
The downside is of course the size and weight of the unit. This unit will definitely need a tripod mount and is not something you could mount on a rifle easily , or would you want to.

The Price.

a Tube will cost (HAS cost me..) £35.00
a lens (already bought one off E-bay – theres loads there , dirt cheap) £5.00
an Eyepiece, – A jewelers Loupe can be picked up off Amazon for £3.00

I have yet to factor in the cost of a Battery case and switch and mount, OR materials to connect the lenses to the device, but they will be cheap. – A visit to a hardware shop should furnish me with the desired bits, – a Tube
(plastic pipe), Glue, tape, whatever…

So far , I have ordered my tube, bought a camera lens and a Loupe. – I will continue this piece when they arrive.

I will leave you with a picture of some finished units that others have made, – some are quite professional,

others not so….

A P8079HP Tube.
IMG_7456-1024

a Good one..
index

A Bad pair.
images

Something along the lines of what I want to do but with a web cam attachment in addition to the eyepiece.
DSCF09333

Afterthought:- Was sad to see on E-bay, many 35mm cameras that cost an arm and a leg in their heyday , going for

peanuts – a Canon A-1 (I used to have one , Cost £500 plus) went for £5.00 . (Wish I had a time machine, -I`d make a fortune…).

Until the next time, Demotricus Tiberius Berk signing off…

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9 thoughts on “

  1. Hi!

    Nice post!

    I´m making a night vision tube with this image intensifier also, actually its already done, but i want to add a gain control circuit to it, so i can control it trough a potentiometer, i read that in other post you said that you buy a potentiometer to control the gain.

    How did you make this gain circuit? can you share the circuit diagram please?

    1. its a VERY simple circuit

      use any linear variable resistor or potentiometer that has a 1 Watt rating or above -(you could probably get away with lower) – make it about 500 ohms- you can vary this too but don`t forget that the lower the resistance, the higher the current it will draw – use ohms law to work out the current through it (V = I * R, or I = V divided by R ) – e.g if we use a 500 ohm VR1 then I = 9 volts divided by 500 ohms = 0.018 Amps or 18mA (open circuit)
      so in other words it will draw 18 milliamps without the tube connected.
      Also , the higher the value of pot you use means that in practice that the smaller the proportion of the pots range will have an effect on the gain of the tube. (it will only seem to make a difference at the top end of the pots travel).

      The tubes gain is directly related to the supply voltage. – maximum supply voltage should be about 9 volts – I use a 5 Volt supply from a USB lead and find that the gain is adequate so I would advise caution using higher voltages.

      You will find that a lower F rated lens will make more difference than the supply voltage and gain so I would advise you to explore that avenue first if trying to get the best performance from this tube.

      1. Hi, thank´s for your reply, i have something similar done, i have a 7,40 volts battery, and then i put a 10R resistor and a 260R pot, this way i have tension off 6,66 volts maximum, and 2 volts minimum. (i think that i dont need less then 2 volts)

        I decide to question you because i have read in forums, that we should use a voltage regulator to stabilize the circuit (lm7805), and then adapt a pot to the circuit to regulate the gain.

        And to tell the truth i was really confused, because i dont have any knowledge in electronic, and all of thats seems really hard to make…

        what you think about that, do you ever heard this before?

        Also, i have the original datasheet that was released by EEV with the tubes in 1982, and in there they say, that the tube uses a single dc input at 6,75 volt, with a maximum comsuption off 50ma, and its regulated to work in peak performance at 4,50 volts. and the maximum input voltage should be 7 volts.

        But they dont say anything about the gain control…

        If you want i can send you the datasheet…

  2. Hi!, – yes, I`ve got that datasheet (somewhere lol!) and To be honest I did not read it – but what you say makes sense.
    There`s no point in using a 7805 voltage regulator really if the device has its own regulator which is set at 4.5 volts, – that would mean that whatever voltage you apply above 4.5 volts is pointless as the device itself will only ever see 4.5 volts. – I did suspect that the gain data was spurious and you`ve just confirmed it for me – in short , with the new information you`ve found – there Is NO point in attaching any type of potentiometer to the device (I did not attach one to mine BTW – I just connected it to a 5V supply rail via a USB lead) – I did read some of the Forum posts and thought until now that there was no regulator fitted – hence the theory behind the circuit I posted, – it WOULD have made the actual voltage reaching the tube variable – obviously it`s all theory now lol!

    For further information BTW – a 7805 regulator is a three pinned device that looks like a power transistor, when you look at the device from the front the three pins are :- voltage in (left pin) , Ground (middle pin) , and Voltage out (right pin) – you apply an unregulated voltage across the voltage in and ground , and 5V regulated is taken from voltage out and ground. – the ground is negative.

    1. hit thank´s again for your reply, i buy my tube from anchorsupplies and they send me a pdf with instruction to construct the night vision tube, and at the and of the page they say that the original tubes was built with a gain control potentiometer, and they recomend us to built one!

      After i read that, i´m looking and searching for the ideal gain control circuit, and i came across with a lot of theories, and the las week i find this datasheet from eev, and i was surprised to find out that in anywere they talk about a gain control circuit, they talk about an internal circuit (inside the tube) that they implement in this tube, that will prevent the tube to be damaged by excessive light.

      if you grab your tube and point it to bright source of light you will see the screen became really bright and then one second after it reajusts the screen to an optimal state of brightness. and thats the protection circuit they talk about.

      So… i supposed that maybe eev only sell the tubes to british army, and the army tecnictians construct the housing of the tubes and maybe that gain control circuit,
      I agree with you when you say that probably a gain control circuit its pointless, because of this internal circuit that adapt the screen to a optimal exposure in case of excessive brightness.

      But a gain control circuit, maybe will be handy in situation off very low light, to give you a little more exposure… could be this kind off gain that british army adapt to the tubes?? that´s what i´m trying to find out…

      1. I think the automatic gain control circuit is like you say , – a protection circuit that reduces the gain internally if the tube is overloaded.
        It`s hard to picture what the suppliers mean by a gain control potentiometer.
        The only parameters that you can control are the supply voltage and the supplied current – the working current is not controllable really – you can stop or limit it if the current passes a threshold but it`s impossible to actually vary the current supplied – you can only vary the amount AVAILABLE, – and if there IS a voltage regulator inside then you meet the limitation we`ve already covered.
        The problem is that there are only two conductors accessible to us – the actual supply rails.
        I`m afraid I don`t have an answer to this problem electrically – but what I can say is that the actual lens you use DOES make a huge difference. – An ideal lens to use is a 35mm SLR camera lens – the F stop should be at least F1.7:1 or below. – there are a lot of older 35mm cameras for sale on E-Bay now, and they are cheap at the moment – The very best lens you can realistically buy would be one rated at F1.2:1 – anything lower than that will be expensive.
        Zoom lenses WILL produce an image but by their very nature, have larger F stops – it`s hard to find one better than F4:1 So the lenses you could look at will typically be 50mm Standard lenses – a 50mm lens is neither a telephoto lens or a wide angle – it gives an image comparable to what you see with the human eye, i.e.- not magnified.
        It would be interesting to find out what the specs of the original lenses used in the chieftain tank were – it would certainly give an insight to what should be used for best results.

  3. I agree with you, it would be very interesting to know the specs of the original lens… the problems with good lens its the money they cost… i have seen in ebay good prices, but i´m from Portugal and the shipping usually costs alot… well, thank´s for all your reply´s and sorry for my English… 🙂

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