Those who have been following my website would remember that I had a big ambition to build an image orthicon camera. Well that project has been put to the backburner due to lack of certain resources and lack of certain knowledge despite reading a bunch of books and IO camera manuals. So I've decided to side step to another project which to my opinion is just as great and that is building a solid state Iconoscope camera!!!:D Reason behind this is, I've been told by tech experts including TV cameramen/engineers that an Iconoscope camera is much easier to construct than an image orthicon camera, plus having an early 1940s RCA 1846 Iconoscope tube handy, it made logical sense for me to shift my focus to building an Iconoscope camera so that's what I'll do!
Before I get into my project, firstly it's important to mention that there are three known operational Iconoscope cameras in the world, two of them are solid state driven with modern electronics and one is a fully restored World War 2 bomber camera block. One solid state Iconoscope camera was made by Paul Marshall in UK back in 1997 which he was using a 1948 PYE photicon midget Iconoscope tube, the details of the camera are on (this page) and the picture can be seen (here) . The other solid state Iconoscope camera was made by famous Japanese Sony senior project engineer Yoshio Ozaki around 2002, he used an early 1940s RCA 1846 Iconoscope tube just like mine and designed/constructed a neat Iconoscope camera from the ground up, I have featured a page on his excellent work with his video documentary on it embedded, to see it (click here) . Over in USA Maurince Schechter has restored an original military Iconoscope bomber camera block to working original condition, it uses a RCA 1846 tube, (click here) to see the details on his restored camera chain.
Now onto the project. So far I've gathered up as much tech info and resources that I can get a hold of. Most of the tech info has been from the net from tube data to general knowledge of Iconscopes to some schematics. I'm currently in touch with Yoshio Ozaki who successfully built an excellent working solid state Iconoscope camera and he is kindly helping me out via email with my project, he couldn't find his original schematics but had some memo note which he kindly scanned and sent to me which gives me a good head start. As for the resources, obviously I've got a RCA 1846 Iconoscope tube that's still under vacuum so that's a good start :) plus I have found a suitable enclosure for the camera which is a computer tower case which use to house an IBM 486 DX2-66 computer, plus I've got plenty of metal pieces, a drill and a rivet gun to make the necessary framing, so because of this I have made a start on the camera. So the construction begins:
First things first the Iconoscope tube. Here is my early 1940s RCA 1846 Iconoscope tube, it is in excellent shape and still under vacuum and there's a good chance it will work! More details on the tube can be seen on (this page) . Now there is no datasheet available on the net for this tube but there is one for the earlier similar tube the RCA 1848 which the specs are pretty much identical, the datasheet can be downloaded from (this link) . Yoshio also used the RCA 1848 data for his 1846 tube. The 1846 tube is the military version of the 1848, the only difference is there is one extra connection on the 1848. Anyways having a suitable datasheet at hand, I know the voltage levels required for each section of the tube.
For the project I decided to make a cardboard model of the Iconoscope tube to close as possible to correct dimensions so I can use it for reference while constructing the tube mounting section of the camera, this is so I don't risk accidentally bumping and possibly breaking the actual tube, that would be a disaster!!!
Some months ago I picked up a computer tower case off the street and gutted the computer system inside which was an IBM 486 DX2-66. When I thought about building an Iconoscope camera, I was pondering a suitable enclosure and this tower case strongly came to mind, so checking it out, with the frame work removed and some new frame work added I thought it would be a very suitable enclosure for my Iconoscope camera and a couple of my tech friends agree too, so this tower case will be my enclosure. So construction begins!!!
First things first, I looked at the big disk drive rack which will house the lens and worked out where the Iconoscope tube will be positioned, I then looked at the dimensions of the tube and looked for a suitable spot to stick a metal platform for the tube to sit on. For the platform I used part of a computer power supply enclosure, I then drilled and riveted the platform to the back end of the of the tower case in a suitable spot.
Here you can see the model Iconoscope tube sitting on the platform and my projector lens sitting in the drive rack, that lens will not be used for the camera as it's unsuitable. This gives a very rough idea on how the tube and lens will be positioned.
But there's more to it, for the tube I need to build suitable mounts with cushioning for the tube's bulb end and tube's the neck with deflection yoke so work begins on making suitable mounts which takes me to the next part.
For the tube's bulb end, I cut out a wood mount concaved in at the top for the bulb to sit in nice and snug, I of course added a rubber lining from an old bicycle tube for cushioning for the tube too. The rubber lining in this pic was replaced with a wider rubber lining so I could nail it to the wood.
Due to the situation of having to place the Iconoscope tube in side on I had to make this wood mount removable so it can be attached to the tube ouside the camera and the tube with mount then slotted in and attached to the base. To do this I had to cut some metal brackets and drill and screw them to the base, drill holes in the wood mount so I can secure it with the tube to the brackets with screws. It required some precision work with positioning the brackets. The wood mount I added a wider piece of rubber from the bicycle tube and secured it to the mount with small nails. Sitting the tube on top it fits like a glove :). In the above pictures you can see the Iconoscope tube seated on its mount on the base inside the tower case and the tube is well aligned at the top for a lens to be centre positioned in the drive rack. I also positioned the mount so that the tube's neck is half way between the base and the drive rack for room to stick a yoke over it.
Next I had to make a suitable strap to secure the tube's bulb end to the wood mount, so from the bicycle tube once again I cut a long strip of rubber and nailed it to the mount on one end and made a used a screw and washer to clip the strap at the other end and as seen it worked out good for the Iconoscope tube :).
After perfecting the mount for the bulb end of the tube, next step was to make a suitable mount for the neck of the tube with the deflection yoke over it, so I had to somehow determine the dimensions of the yoke. I went by Yoshio's notes on the deflection yoke dimensions and made a cardboard model of it and then constructed the mount to for the yoke to correct size, I had to make the concave part of the mount slope diagonally as well so the yoke sits in at an angle, so that required a fair bit of grinding! Then I had to cut a metal plate for the mount to sit on, plus the mount had to be height adjustable to get the best possible positioning for the tube's neck/yoke so had to drill/cut elongated holes in the plate. I then riveted the plate to the base in the enclosure.
The above pictures show the construction stages for the tube's neck/yoke mount and the cardboard model of the tube/yoke sitting on it. I am quite happy with the results so it looks like the tube's mounting is nearly complete. I just have to build the yoke and find a suitable way to strap it to the mount so that will be a bit of a wait as I'm yet to get all the data necessary and resources to build the yoke.
No construction progress to date but am trying to put together a design plan and list of essential circuitry for this camera. Here below is the data for the RCA 1846 iconoscope (actually 1848 but specs are identical to 1846) followed by a very basic block diagram of the Iconoscope camera system which is pretty much the basis of all tube cameras, I will soon do a more detailed block diagram expanding on each section:
Part 1: Introduction to my Iconoscope camera project
Part 2: Cardboard model of Iconoscope tube
Parts 3 & 4: Construction work and modification of the computer tower case into an Iconoscope enclosure
Part 5: Constructing the mount for the Iconoscope tube's bulb end
Part 6: Constructing the mount for the Iconoscope tube's neck and deflection yoke
In the diagram as seen is the very basics. I pretty much made this diagram based off a vidicon camera block diagram as the root basics are pretty much the same, you need video amp/processor circuitry for the signal coming from the target, deflection circuitry for the horizontal/vertical deflection yoke, sync pulse generator to provide the deflection circuitry the horizontal/vertical syncs and of course the power supply to provide power to the tube and the above circuits.
Firstly there's the video amplification and processing circuitry, it starts with a head amp close as possible to the tube's target connection to amplify the video signal from the Iconoscope's mosaic with minimal noise, then there's further amplification followed by video processing circuitry where the syncing and blanking is added and shading correction is required to fix the Iconoscope's trademark shading effects as best as possible to output a best possible quality picture.
Secondly there is the sync pulse generator and horizontal/vertical deflection circuitry which provide the the horizontal/vertical drive signals (sawtooth waveforms) to the horizontal/vertical deflection coils of the yoke for raster scan, in the deflection circuitry you have the input horizontal/vertical signals coming from the sync pulse generator circuit which those signals get amplified and synchronized and outputted to the horizontal/vertical deflection coils of the yoke to drive the beam to scan the the mosaic. Also due to the fact the Iconoscope's beam scans the mosaic at a 30 degree slant, normal scanning results in a trapezoidal (keystone) shaped raster so keystone correction circuitry is required in the deflection circuitry to fix this issue to bring about a 4:3 rectangular raster. And also dynamic horiztonal/vertical scanning is required as the beam takes longer to reach the upper region of the mosaic than the bottom region due to scanning from a slant. This all can be better explained Richard Diehl's 1945 RCA CRV-59AAE Iconoscope Camera page on his Labguy's World site.
Thirdly of course there is the power supply unit which provides power to the the above circuits as well as essential power to the Iconoscope tube which requires high voltages reaching in excess of 1000VDC. It is essential the power supply includes an automatic cut down circuit for the beam current to prevent excess current/voltage hitting the mosaic target causing damage to it, according to the spec sheet the beam current is typically 0.25uA.
So that's my basic understanding of what's required for this camera, if I've made any mistakes in my explanation, pop me an email at email@example.com and correct me as I don't wish to mislead anyone with misinterpreted information.
Here below is the 2nd part of the 1848 spec sheet detailing the dimensions of the tube which I will bring me to discuss the lens to be used:
Now I have been very curious as to what lens has to be used for an Iconoscope camera due to the fact that the mosaic is much larger in size than what a standard lenses for most cameras can accommodate for in projecting an image to it, so I posted in the NBTV forums questioning what kind of lens would be suitable for Iconoscope tubes and one of the members suggested I use an old photo camera lens that projects to rolls of film that are 6x9cm or 6x6cm and also check the size of the mosaic as well. The size of the mosaic in millimeters is 76x57mm so a 6x9cm photo camera lens or anything around the mosaic's dimensions would be most suitable for projecting an image to the mosaic. So now will have to do some lens hunting.
So this is where I am up to so far with my Iconoscope camera project, it's a good start so far!!! :D There is so much more to do yet so I will keep you all updated as I progress with it. I am currently gathering up more pieces of information such as a list of vital design requirements for the circuitry, block diagrams of the camera's various circuits, lists of needed parts etc...
Yoshio suggested I get a hold of an old 3 tube colour camera (I assume a 70s plumbicon camera) and modify the circuitry to operate for the Iconoscope tube. I've also read about Paul Marshall's PYE photicon Iconoscope which he used a plumbicon camera's video circuitry for his camera too. I am not particularly keen on the idea of scrapping a 3 tube camera especially if it's working but I am willing to construct the necessary circuits from a 3 tube camera for the Iconoscope so I am after service manuals for 3 tube plumbicon colour cameras of the 70s era, so if anyone has any such manuals contact me at firstname.lastname@example.org .
Speaking of Paul Marshall's PYE photicon midget Iconoscope camera for those interested in knowing more about his camere, there is two big articles on it in CQ-TV magazine's 1998 issues 181 and 184 which can be downloaded here from the BATC site. And of course a photo of his camera's interior and screen shot can be viewed here and the tube itself can be viewed here.
I truly need all the tech help that can be offered to help me construct this camera as there's a lot for me to learn with constructing an Iconoscope camera. I admit I don't know how to design complex electronic circuits, that is above my current scope of knowledge so that's where I mainly need the help the most! So anyone who is as enthusiastic as me in having an Iconoscope camera build and is keen to assist me on this project particularly with designing the circuitry, you can contact me at email@example.com , I look forward to hearing from you! I basically work like this, you design me the schematics, I go buy the parts and build the circuits.
Stay tuned for the next update.......
Well it's been a few months since I last did anything with my Iconoscope camera construction, I have been gathering up data and emailing electronic experts during the hiatus and have got new info to work with and have picked up where I left off.
So what have I worked on recently, well I have made myself a homemade rackable focus camera lens for the Iconoscope camera. Yep I had to make a lens because the lens I needed for an Iconoscope tube was not easy to find. Basically my RCA 1846 Iconoscope tube has a photosensitive mosaic plate at the size of 78mm wide and 57mm high and a standard C mount lens or even a 35mm film lens will not cover an area that size. I asked around for help and it was suggested I try getting a lens for large film cameras that take film of 9cmx6cm in size, also it was suggested I use a powerful magnifying glass. Well those camera lenses are not easy to come across so I chose the latter which was to make a lens from magnifying glasses. So I experimented. To start with I tacked 2 magnifying glasses onto a plank of wood and focused an image onto a piece of paper with a drawn rectangle the size of the Iconoscope's mosaic and was impressed to see a nice big image projected to the piece of paper with an area far surpassing the size of the mosaic area. So I decided to start making me a lens system.
So I went to an el cheapo store and bought a few $2 magnifying glasses. Now I took things a little further and tried out using three magnifying glasses close together and found that the image was a bit smaller but still fit the mosaic size and the image was a lot brighter which was beneficial for the Iconoscope due to its poor sensitivity. So I started making myself a 3 magnifying glass lens system. I cut the handles of the magnifying glasses and used some cardboard tubing to house the lenses inside and got myself a nice neat looking home brew lens. I glued the lenses inside the tube and let it dry overnight.
Then things went pairshaped the next day. Due to wet weather conditions, the lens system fogged up in the inside causing the focused image to be hazy which was not cool. Also another problem I discovered too was the focal distance from the lens system for distant shots was too short which required the lenses to be too close to the Iconoscope tube which is undesirable.
After experiencing those two issues I decided to drop back to two lenses, primary reason of course is to increase the focal distance. So using two lenses and this time using plastic from a DVD spindle case for tubing I housed them inside and hot glued them in place and made another lens system and no lens fogging has occurred since and the focal distance is good. I also found a suitable railing to rack the lens back and forth as well, an aluminum front panel of a junked sound system I pulled to bits. I sawed off a section of it and sawed the protruding railings down till they were flush with the rest of the panel so the lens can fit inside the camera enclosure on it. So now having a good lens and rail for racking I decided to test out focusing an image inside the camera enclosure onto the paper with the drawing of the Iconoscope mosaic area and see how it goes and I had the paper positioned roughly where the tube's mosaic is situated. It turned out good and the lens slides along the railing nicely.