Video on Oscilloscope (Easy!)

Here is the easiest way to put video on an old analog oscilloscope that has "Z axis" inputs (usually on the back of the scope:

It uses an LM1881 integrated chip and nine other little components to display live video on an oscilloscope screen.

You'll need the following:

(3) 0.1uF caps

(1) 4.7Uf cap

(1) 1000pF cap

(1) 680k resistor

(2) 100k resistors

(1) LM1881 chip

(2) IN4148 diodes

Plus: an oscilloscope with a Z input; a video camera with a composite video out (usually a yellow RCA plug); two thin wires to go to Z input; a DC power supply that can be adjustable to +5vDC (you'll probably need around 3-4vDC); a composite RCA cable to run from camera to circuit; a breadboard or soldering iron; breadboard jumper cables; wires from power supply.

Here's my version on a breadboard. It's only 10 components but I used a lot of jumper cables to keep things simpler for me to see.

Below is a drawing of the end of the RCA cable coming from the video camera (or TV or VCR or DVD player or videogame console, etc.). The pointy tip is the positive signal. When you're all done you could run a ground wire from the ring/barrel negative part of the RCA plug--but I found it made zero difference on or off, so I'd leave it off.

You'll see nothing until you hook up the wires to the Z axis (intensity) of the oscilloscope. The picture was black and green, upside down and mirror-image flipped. I pointed the video camera at a TV set. Here is a Voltoren medicine commercial.

This photo is of a episode of The Three Stooges. It's hard to see in the photo, but it's the episode where Larry dresses in lady's clothing and tries to seduce members of the Nazi Upper Eschelon. Shown is "Admiral Boring" (Goering) giving the Hitler-salute to Reich's-Fuhrer Moe! It was a weird episode.

User caveats:

1. Use XY mode on the oscilloscope. 

2. The black (negative) bands of the diodes should be closer to the LM1881 in the circuit path.

3. Z axis are not reversed, like other versions of this circuit in books. Z Axis + goes to the center pin tip of the RCA plug. Z Axis - goes to the ring/barrel/negative/ground of the RCA plug. When I reversed them I got no picture.

4. The camera (mine was a 1980s JVC) had to be "zoomed in" for this to work. I don't know why! If I zoomed out to wide-angle the circuit stopped working.

5. You only get a small portion of the video that the video camera sees!

6. I set the video camera exposure control to "+" for a brighter image.

7. With 3.6vDC to 4.1vDC I had much less noise in the video than running at 5vDC. Fiddle with the voltage.

8. The oscilloscope probes I used are newer ones that have 1x and 10x. Use the 1x setting, it got a much better signal for this usage. If your probes don't have a switch on them--they're probably 1x anyway.

Some random shots of my self-assembled Elenco kit power supply (from Amazon or eBay). My $5 HP analog oscilloscope from an antiques store/resale shop. The settings on the scope aren't exactly what I ended up using, but they're in the ballpark. As you can see my X and Y are actually A and B on the scope! There's also an unused horizontal input. The "Z axis" is in the back of this scope: so I ran two wires to the two screws in the back and have them wrapped around the front handle for easy access (instead of reaching behind this super heavy scope all the time).

I set the inputs to "DC" which gave a better image. I think "AC" worked by spread out the the signal and made it way worse. The "BW limit" was off (made a small difference). X vs Y setting. Scope was set to "CONV" which is the normal display setting on this scope (your scope probably won't even have that option). In the end my X and Y (or A and B) were BOTH set to ".2" on the knobs.

In the end I realized my dream of watching an episode of Columbo in Black and Green on an oscilloscope. My bucket list (other buying a new 2021 Ford Bronco) is pretty much complete.

This is one of the chickens that rampaged all over the neighborhood:

                                                                           Delicious!