Remote Selection Video Switch for Security Surveillance System


A video switcher (also called vision mixer, video mixer, or production switcher) is a device used to select between several different video sources and in some cases composing video sources together to create special effects. This is similar to what a mixing console does for audio.

The A/B Switch circuit consists of three ICs and a handful of resistors. Two gates from a HEF4011BT quad 2-input NAND gate are configured as a monostable multivibrator that, when switch S1 is pressed, triggers a 74HC4017PW decade counter/divider, which has been set to recycle after a count of two. The outputs of U2 at pins 2 and 3 are fed to the control inputs of U3 (a 74HC4066N quad bilateral switch) at pins 12 and 13. Depending on which control input is high, either the J1 or J2 output is selected.

Remote Selection Video Switch

With a little modification, the switch could be set to trigger at a set rate (automatically). With the addition of another 74HC4066N, it could have as many as 8 channels. One possible application would be in a security surveillance system.

Components:

  • 74HC4066N Quad single-pole single-throw analog switch
  • 74HC4017PW Johnson decade counter with 10 decoded outputs
  • HEF4011BT Quad 2-input NAND gate
  • Switch Normally Open
  • 470Ω Resistor
  • 100kΩ Resistor
  • 22MΩ Resistor
  • 100kΩ Resistor
  • Light Emitting Diode – 2 Units
  • Low Voltage Power Jack – 3 Units
  • 0.1 Capacitor

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