TV To Scope Converter


Posted on Feb 6, 2014

This project takes after the VGA-to-Scope converter by using composite video rather than VGA signals to create a display on an oscilloscope. The circuitry in the VGA-to-Scope converter has been greatly simplified; op-amp buffers and inverters were eliminated. The continuous current supply to charge up the capacitor linearly (the 3906 PNP transisto


TV To Scope Converter
Click here to download the full size of the above Circuit.

r and associated resistors) was replaced with a simple 1Meg pot from 5V to charge up the capacitor, albeit creating a nonlinear sawtooth. When the pot is set just right, the capacitor will charge up at the correct rate and the trigger signal causes the 555 to discharge the capacitor for synchronization. Below is the schematic. A LM1881 is used to do all the grunt work of separating the sync signals from the composite video. The chip provides the vertical sync on pin 3 for the vertical oscillator, and composite sync on pin 1 for the horizontal oscillator. The intensity signal comes from the composite video signal itself, but is negative. I didn`t really mind since this circuit took only 10-15 minutes to slap together. If an inverter is preferred to make the video "positive" then here is a schematic for the inverter below as taken from the VGA-Scope converter. This circuit includes another 555 to generate the negative supply rail for the op-amps. CAUTION: The oscilloscope must have a X, Y, and Z axis, good gain, and X/Y inverters for this converter to be useful. Second, the video MUST be connected before you turn up the brightness of the oscilloscope. Without the video signal connected, the sweep generators are not operating due to the absence of sync signals so a dot appears on the CRT, which can burn the phosphor. Make sure you have a raster before you turn up the brightness. The same goes for shutting down, turn down the...




Leave Comment

characters left:

Related Circuits

  • New Circuits

    .

     


    Popular Circuits

    Audio PreAmp MIC (dynamic)
    Basic Oscillator (Tone Generator) At 1.8 KHz -alarm circuits
    RS232 Reset for Microprocessor
    Higher Order Filters
    Rain detector electronic circuit project
    555-Circuits
    Ultrasonic remote control switch circuit diagram
    ISO122 124 filter circuit diagram
    Battery over-discharge protection circuit diagram



    Top