Klaas Robers wrote:Harry, if you look through a sheet of yellow plastic, or use a Yellow Filter as was used in the time of black and white photography, you will suppress the visibility of the blue light of the laser and see only the green fluorescence of the painted tin. I also used that in 1973 in front of the screen of my 7BP7 SSTV monitor tube.
Now I see that the drum rotates very slowly, so you can see the picture building up while it scrolls up slowly. This has an extra advantage. If you write e.g. about 3 frames around the rotating drum, the previous picture is faded out much deeper than it was on the screen of the 7BP7 CRT, as in principle you have 3 screens that are used one after the other, in stead of just one.
Hi Klaas
Thanks for posting I had no idea about the yellow filter thing mmmm interesting ,i will try and track something down i have filters of just about all colours and between i used years ago in colour photo developing ...now what have i done with them when i need them !!!
But i will try it out Klaas.
Yes a trip to my junk box to find something that i could test my stepper motor circuit on led to this idea ....i know what you are thinking on having say more scans on the drum so its all in view is something that popped into my head as well when i got it going but i didn't think of say 3 extra new scans ,i would be getting ahead of my self but sounds good thing to try if i can get there ; ).
One thing that i was thinking if i can get this thing going is it might be able to do P16 or and perhaps P32 line but might be pushing my luck with those ideas.
As you know i will have it on its side so the scan will look like a sort of curved crt but i don't think it will look to bad seeing the lines painted on half a tin is pretty viewable and yes again i agree to try and scan part of the drum ...i have not played to much around with speeds yet i am remaking a stepper motor controller just for this and thinking about the
best way to control that polygon mirror ...thinking of using my sstv circuit lm565 PLL horizontal sync feeding to a 555 timer monostable pwm circuit for this ...