circuit to modify in real time old analog video signal.
The project is still going on. Almost done. A syncable VCO modulated by another VCO have been added and can also module the 4bit converter and the keyer. Quite happy with the results ! Next steps, building a box for it and maybe built a version with a Microprocessor for the additional modulation (and reduce part count).
Knowing that everything work, I kinda become lazy on this project (also that I switched to a linux machine, what a change...) however the project took a step further. I originally planed to only use the video processor but it'd be a miss to not add at least an horizontal oscillator (strips). Considering the low maximum frequency (about 5Khz) I went for a LM13700 VCO (cf. datasheet) and some waveshaping to have proper amplitude and bias. Vertical oscillator (bars) is a bit more tedious as the frequency should at least go to 500khz (but mroe about 1Mhz)
(The decision for the additional circuits was hard, considering the modularity of the system everything could be done. From a simple video modificator to a fully modular with patch cable. But I want to keep the thing simple and easy)
I also made my mind, no microcontroller on this project. Full analog for all the nerds out. A simulation of what it could look like . The boxing is always a pain for a one-off project.
the board is working fine. I made a crude test jig out of MDF panel. I decided to give a separated control for the solarize fonction. I was fearing for the LT1054 to be noisy but things are very clean. I'm now working on a daughter board to produce a Horizontal VCO (LM13700) and other things to play with (burst, enveloppe). However even as it, the circuit is fun to play.
The input/output of the circuit is working fine. The NX5DV330 is doing fine as well(but no longer manufactured).
I had this project in mind for sometime now. It is inspired by an old 80's magazine project called the "video palette". It offers several effects to toy with the video signal that has been split from the sync signal. There're two big circuits, a keyer and a posterizer and a rotary switch just send the proper signal into the keyer (negative, posterizer,...). There's also a lowpass filter to blur the image.
I wanted a bit more lo-finess to it so I added a microcontroller (STM32F03F4) and a 12bit DAC to generate others signal that could be mixed with the video signal (as well as a midi input). Considering the lack of video encoder, the signals will only be black and white.
Considering the bandwith requirement it's always a bit tricky to select part, especially for the multiplexer. Too much ON Resistance in the switch and you loose sharpness. For the main multiplexer (the one that split the signal and re-sync it with the modified video) I designed the PCB for two options: The NX5DV330D which is a video-multipler and could the job nicely and the trusty CD4053.