Intro: Visualist, 80's Analog Video Effects Controller
Realtime Video Effects With Sound Reactive Psychedelic Visuals.
Searching the internet you can find many audio effect circuits but analogvideo effect circuits are rare. Why?
Is there no interest? Visualist is a project out of 2011 but I didn't published this on Instructables, up to now. This real time false color video instrument for VJ's, DJ's and other artists is great for live shows.
The video circuit was first published in the German Funkschau magazine a long time ago. The circuit is cheap. The MC1377P is the only non regular component. Sound- and video circuit can be build for about 60 dollar.
Take care, only people with enough electronic skills and with an oscilloscope can bring this project to a good end. Sorry.
Step 1: The Video
Step 2: Block Diagram Video Effects Controller
The first picture shows the block diagram of the video board; a kind of flow diagram. In this circuit the color video input signal is made into a b/w signal by cutting off the color burst using a notch filter (10.7Mhz). It's not perfect but it's sufficient.
The signal is split in 2 directions:
1- Via the comparator IC1a the sync pulse is passed to the oscillator IC4c/d (31250khz) to make a semi-normal PAL-sync-mix for IC9, the "famous" MC1377P RGB to PAL/NTSC encoder.
2- The way through the seven comparators IC1 and IC2.With six resistors between IC3a/b we can control the upper and lower threshold and the threshold for every luminosity level in between. In other words, the signal will be "sliced" into 7 luminosity levels. Each level will produce a color out of a range of combinations chosen by IC6 and IC7. The comparator potmeters are fine to experiment with. In the video you can see the wonderful effects.
It's in fact a "false" color generator. After the comparator the signal passes through a priority encoder IC5 that results in a 3-bit-word. IC6 and IC7 (1 out of 4 analog switches) are doing the color change. The 2-bit control signal is made by IC10 and IC4a/b.
Pressing the "color select" button briefly makes a color change; holding the button down makes a continuous color change. More effects are produced by the RGB inverter switches; they invert the color layers.
Step 3: The Soundboard
The block diagram of the sound board shows the selection switch between the built-in microphone and the line input. After that comes the automatic volume control. Third is the filter for bass, mid and high tones. Last are the LED drivers for the Light Dependent Resistors. They control the RGB color saturation in the output video signal.
The second picture shows the sound circuit.The third picture is a photo of the sound board built on a single island board.
Picture four shows the 3 voltage regulators on the top and the LED/LDR bridge on the bottom.
Changing the three 560ohm resistors by 470ohm potentiometers at the video board, and parallel to this a light sensitive resistor makes that the color of the VISUALIST reacts on the sound of a microphone or an audio line-input. So, we get hand- and sound control together. The sound circuit is an Elektor design and is a LED color organ. The automatic volume control makes that hand-control is not necessary by wild changing environmental sound. You can see the printed circuit and layout of the Elektor design in picture five and six.
Important is the use of light sensitive resistors in the videopart. They merge sound in the videosignal.
Step 4: Building the Videoboard
Picture one shows the printed circuit board. Picture two shows the component placement on the board.
Take care; make good solder connections. Make first all the wire bridges; after that place the IC pins. Work clean. Picture three shows the oscilloscope signals for calibration on the test points. Picture four shows the components at the video board. The signal cabling between the switches, potmeters and audio/video board has to be of good quality. Most connections are done with coax wires.
For finetuning the videocircuit an oscilloscope is required. A list of testpoints and signals you can find in picture three.
Step 5: Lay-out of the Controllerbox
I build the Visualist in a microphone box. Also a small monitor is build-in. You are free to position the buttons and potmeters in the way that is fine for you. The input of the Visualist can come from a PAL or NTSC camera, videoplayer or computer. You have to switch on the board to the videosystem of your choice. The output can be a videoscreen or beamer.
Very important is the way you light out the objects in front of the camera. This influences the shape of the seven luminance slices. Here a video with normal and processed signal with just a few luminance levels: