Video Switch for ATV

After being active with ATV on several bands with multiple video sources, I felt the need to have a video switch. With this I do not have to plug one video source to another anymore, it saves time especially when working in a contest.

Overview of video switch unit.

The basic video switch modules were taken from an existing Barco RGB switch unit as well as the power supply. The controller is homebuild, so is the new frontpanel (tnx to Jos, PA3ACJ), the cabinet came from an old rf instrument.

The Video Switch unit is  build round 3 modules, each module has four  (4) inputs and one (1) output, can also be used in reversed mode (1 input, 4 outputs). The unused inputs are automatically terminated with 75 ohm.

Control of the switches is done through a simple 2 button interface, the MOD button selects the correct module (LED under 1st BNC is lit), the SW button then selects the correct input (LED under 2nd, 3rd, 4th, 5th BNC is lit). Only one input per module can be active (it is not a matrix input).

The two remaining buttons (P1, P2) are preset buttons, pressing these buttons will load a (self defined) configuration, this allows the user to switch quickly between two configurations.

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frontpanel view of menu switches and on/off switch

All four buttons have also a second purpose when holding longer then 1 second :

  • MOD Button :  stores current setting into powerup setting;
  • SW button : erases all stored settings (cleans eeprom);
  • P1 button : stores current setting into Preset 1;
  • P2 button : stores current setting into Preset 2;

If saving was successful, three LEDS will flash 3 times.

internal view of one of the switch modules
internal view of one of the switch modules

The controller is homebuild but follows the arduino ( structure, code is written using the arduin IDE in C/C++ and is available on request.

To  control the twelve relays and three extra LEDS, two shift registers with opendrain output have been used, this saves an extra OC buffer.

Controller board (2x shift register left, controller right
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One module with BNC inputs

Although not visible (yet), the unit is remote controllable via USB, commands are already implemented but I need to add hardware.

Commands via the USB bus :

  • Query commands:
    • Id ;
    • Status switch1, switch2 and switch3 ;
    • Firmware revision ;
  • Set commands
    • Set relays of switch1, switch2 and switch3 ;
Original Barco power supply.

Schematics can be found here video switch v2.