One thing I found was I was getting a very rough far from perfect 50Hz sine wave for the vertical drive and was wondering why, but then I realized the return lead from the camera tube heater going back to the transformer needed to be also connected to earth, so I did that and bingo, a nice 50 Hz sine wave derived from mains power frequency! Next I discovered another silly mistake I made which was I had both FET transistors TR1 and TR21 in the wrong way so no wonder I wasn't getting pictures!!! So I put them in the right way and voila, that fixed a lot of the problems!!! I also added those caps to the ICs as instructed by Richard.
Then using my new Tektronix CRO I checked the waveforms and am now getting the right waveforms for the horizontal scan section and the vertical scan input section and I was very pleased. I then with the CRO lead at the output of pin 3 of the 555 timer IC I adjusted the horizontal scan waveform to the required time period of 63.5uS which brought the horizontal scan into good sync and so the video output is now stabilized with no rolling dashes. I also checked the horizontal output and it looks good. Below are pics of the main waveforms from the horizontal scan:
Horizontal scan waveform at output of pin 3 of 555 timer
Horizontal drive output signal to horizontal deflection coil
With the horizontal scan looking good and the above faults fixed I did some adjustments to the adjustment pots untill I started seeing a very squashed partially recognizable picture located at the top of the TV screen!!! This was fantastic news for me as it means the camera tube is working and the video circuit is working and I am now seeing a picture WOOHOO!!! :D Here below is a YouTube video of the camera outputting a squashed picture, in the video you'll see my hand waving in front of the lens.
Now that I am sort of having a picture I am now looking further to find out how to make the picture fill the whole screen. I sent Richard pictures of the waveforms for the horizontal and vertical and he immediately identified the main fault causing the picture to be squished which happens to be the vertical output drive signal which should be a sawtooth waveform but on the CRO it looked anything but a sawtooth as seen below:
A barely recognizable squished picture coming from my camera
Vertical drive signal in its incorrect form, the cause of the pictures being squashed
Richard discovered that the 4.7uF capacitor at output of TR19 is way too low which is why the waveform looks the way it is so he suggested I put a much higher value capacitor in place of the 4.7uF, so I experimented around with a few capacitor values and decided ultimately to put a 47uF in parallel with the 4.7uF totalling the capacitance to nearly 52uF. Adding that 47uF cap has made a remarkable improvement to the picture as now the picture spans to 4/5 of the TV screen and the pictures are now looking so much better and even more recognizable WOOHOO!!!!! :D I love making excellent progress with this camera, my camera is really coming to life!!! Here below is a YouTube video of the camera outputting more reconizable pictures as a result of adding more capacitance to the vertical drive and a picture of the vertical drive waveform and some camera snaps off the screen.
My camera now outputting more recognizable pictures spanning down 4/5 of the TV screen
Vertical drive waveform looking much closer to being the proper sawtooth waveform it should be
Some screen caps of the camera outputting pictures
Now the pictures whilst are more recognizable they are still far from perfect. Firstly the picture is still not quite spanning the whole TV screen and is stretching as the vertical scan progresses further down the screen. That is still due to the vertical drive as it is still not quite a sawtooth waveform. That will be something I will work on later. But now I can see another obvious issue I need to deal with which is the picture is at a 30 degree slant. That had me pondering for a little while until I thought of the focus and deflection leads being in the wrong way around so I decided to one at a time reverse the focus, horizontal and vertical coil leads around voila, the picture is now very close to horizontal and looking MUCH better WOOHOO!!! :D Here below is a YouTube video showing the pictures that are now coming from this camera and I talk a bit in this video about the camera and the progress made and the current issues with the camera that need to be addressed. Also below that some screen caps.
My camera now outputting even better and more recognizable pictures!!! :D
As seen in the video I have found another issue with the camera which is the focusing. I seem to either have a choice of a bit of a tilted image and nearly good focus or very bad focus and a straight image. I was told this would be a back focus issue, unfortunately due to the fact the lens mount is attached to the camera yoke assembly the back focus is fixed so nothing I can do about that. I checked the focus current and it appears to have major AC ripple as I am getting a sawtooth waveform as seen below, the current is about 0.1A which would be about right.
Some screen caps of the camera in action
Lastly I added the 75 ohm resistor to the video output of the video circuit as the picture was overblooming on the output, plus seeing this resistor being at the video output in the Sony AVC-3250 schematic it made good sense to put one at the video output of my camera. And indeed it did as the camera is outputting pictures much closer to the correct brightness/contrast levels!
So the progress with this camera is looking VERY VERY GOOD and I am very proud that I have made it this far with my homemade camera!!! :D There's still a lot of refinements needed to be done to make this camera output pictures that are comparable to say a Sony AVC-3250CE, plus the circuit design will obviously need modifications.
Stay tuned for more updates in the not too distant future!
Here is a direct video feed from the video output of this camera showing how the pictures currently look from this camera. Below is the same video but with the brightness and contrast enhanced.
I FINALLY fixed up the vertical scan issue and I now have perfect sawtooth waveform and I now have a brilliant picture!!!! For a few months on and off I've been trying all sorts of ways to get the damn vertical scan working properly and get a linear sawtooth by ramping up the capacitance from 4.7uF to over 50uF and beyond which helped a bit but caused other problems, even added resistors here and there and changed the zener diode but no luck. I then have been posting in the forums my vertical scan issue and asked a few tech friends and someone suggested I temporarily pull MPF102 FET transistor TR21 out and check the waveform across the 4.7uF capacitor, so I did that and BINGO, perfect sawtooth waveform. I then queried about the MPF102 FET transistor and someone suggested that it could be defective, so I went to Jaycar and bought a few MPF102s and replaced the faulty one in circuit and fired up the camera and BINGO, perfect sawtooth and great linear picture!!!!! :D
I have also dramatically reduced the focus current AC ripple problem on the 28v rail by beefing up the filter capacitance to nearly 5000uF.
So now my camera is really working this time!!! Still not perfectly as the picture is noisy due to target lead being unshielded and too long but good enough to make decent pictures that are nearly up to par with a professionally made vidicon camera if you minus the target noise. So there's still those little refinements needed to be made for the camera to make pictures comparable to say a Sony AVC-3250 camera but for the simplicity of how the circuit's designed, the pictures are pretty good!!! Also the vidicon tube seems to have very poor sensitivity in lowlight so this camera is best used outdoors.
Anyhow here below are pictures of the camera in operation plus some videos made directly from the video output of this camera.
Perfect sawtooth waveform for vertical scan, looks doubled up because the I couldn't quite get the CRO triggered properly
This camera now produces a brilliant image after fixing that vertical scan issue!!! :D There is still the noise issue as seen on screen but that will be fixed by shortening the target lead and shielding it. Otherwise, a very nice picture!
An off screen mobile phone video of my camera in operation
Doing some electronic focus adjustments using what's on the screen as a guide
Me adjusting the camera's various controls for optimum performance
Playing some videos off the computer, in lowlight the vidicon tube has poor sensitivity hence a very dim picture
A video of the camera filming whatever I play on the computer screen
Camera pointed to the kitchem microwave. As seen the vidicon has very poor lowlight sensitivity, had the iris wide open to even get a dim picture.
Here below are a couple more videos made from this camera, one is of myself in front of the lens talking about the camera and the other is some random shots of the front yard from my bedroom. Enjoy! :)
To finish off I am very happy that my camera is now working making great pictures that are usable for filming and am proud of my work! :D I can of course do further work to this camera to make even better pictures which I will do as my knowledge progresses, but for now I am very happy with the pictures the camera currently makes!!!
Now this project is a lead up project to my major project which is to build a solid state B&W 3" image orthicon tube camera which has been in the pipeline for over a year. Now that I've got this camera working I am even more confident I will successfully build one. Since I first thought up of the solid state IO project last year I have gathered up a lot of info and parts and have gained a lot of knowledge about camera electronics, especially in building this vidicon camera so I am better equiped as well! When I get started on the solid state IO project I will start a webpage on it on this site.
I am also planning on building a more compact refined version of this camera by placing the components closer together on smaller boards and positioning the video board closer to the yoke so I can shorten the target lead for reduction in external noise. And of course I plan on housing the more refined edition inside a camera enclosure to make it more practical for use.
Another plan with this camera design is to modify it a little to drive a 1 inch vidicon tube and perhaps other tube types of similar size.
And also I am thinking and wondering of the possibility of adapting this vidicon camera circuitry to drive an image orthicon tube i.e. the timebase board for the scanning/deflection/blanking etc. and the video board to amplify the target signal coming from the image orthicon, it might work with only some mods or it might need total redesign but it's something I am going to look into.
Anyways stay tuned for further updates with this camera, I will be making more videos and will do some refinements in the near future.
Since 2013 I have been working on building a homemade Iconoscope TV camera using my early 1940s RCA 1846 Iconoscope camera tube and during 2014 my friend Richard Diehl of Labguysworld.com has given me some ideas to try to get the Iconoscope tube to output a picture and ultimately his ideas has pointed me in the direction of using the video and deflection circuits from this homemade vidicon camera. So around mid 2014 I officially decided to try using the circuits from this camera and so this marks the fate of this homemade vidicon camera! I disassembled the vidicon camera removing the video board and the deflection board and two of the transformers and so this is what remains of the camera.
Alternatively I could of duplicated the circuits but that was too labour intensive for my busy schedule and sourcing the hard to get parts from overseas is a pain in the arse, so had to do what was most tangible in order to stay motivated with building my Iconoscope camera. In the end it was totally worth it because my Iconoscope camera is working outputting pictures being driven by the deflection and video boards from this vidicon camera and with not much modification at all too, how cool is that! :)