How to Build a Simple Oscilloscope

Written by david weedmark Google
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How to Build a Simple Oscilloscope
A simple oscilloscope can be made from an old computer monitor. (waveform 20 image by chrisharvey from

An oscilloscope is an electronic device that gives a visual representation of electrical signals, most often seen as a vertical or horizontal line that moves in different patterns on a cathode ray tube (CRT) depending on the signal it is receiving. Old televisions and computer monitors (CRT versions) already have the tube and wires needed to make your own simple oscilloscope. These instructions show how to make one from an old CRT computer monitor.

Skill level:

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Things you need

  • CRT monitor
  • Screwdriver
  • Wire cutters
  • Electrical tape
  • Amplifier

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  1. 1

    Unplug an old CRT monitor and pry off the back plastic case. Most models require only a screwdriver to be inserted into clips at the bottom of the case in order to remove them.

  2. 2

    Locate the two sets of coils inside the monitor, usually located midway, wrapped around the cathode ray tube. These are the deflection coils. Two coloured wires are connected to each coil yoke. Generally, the blue and red wires control the horizontal synchronisation of the picture, and the brown and yellow wires control the vertical.

  3. 3

    Cut the vertical synchronisation wires with wire cutters. This will give you a horizontal line on the monitor when it is later plugged in.

  4. 4

    Attach the vertical synchronisation wires to the "audio out" wires of any amplifier using electrical tape.

  5. 5

    Replace the cover of the monitor. Be careful not to pinch the protruding wires. The wires can be run through ventilation holes in the monitor, or you may wish to cut a hole into the case with a utility knife.

  6. 6

    Carefully plug in the monitor. Look for a horizontal line to appear on the monitor.

  7. 7

    Turn on the amplifier and play some music. Adjust the volume as necessary to get the best results from your oscilloscope.

Tips and warnings

  • Opening the case of any monitor or television can be dangerous. Even when the monitor is not plugged in, it can still carry an electrical charge. Modifying the interior of a monitor can be an electrical and fire hazard. You should have prior experience working with electronics before attempting this project.

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