Display Letters and Words on the Oscilloscope





Introduction: Display Letters and Words on the Oscilloscope

"Why you do this ?" Because it's cool and it makes me feel so nerd. And everyone love nerds!

Step 1: What You Need to Do This

1 x oscilloscope with XY mode

1 x breadboard

1 x Arduino or a Fartduino or whatever you want that has a 16 Mhz ceramic resonator

And some wires

For the RC low passfilter:

2 x 10kohm resistors

2 x 0.1 uF capacitors

Step 2: Wire Everything Up

Do you really need explanation for this?

Step 3: A Little Bit of Boring Theory

The RC low-pass filters are used to remove the jitter of the 2 PWM signals. The PWM signals jump from point to point and the interpolation between them is made by the charge/discharge curve of the RC circuit.

If you need more information go to the creator's website where you can find also the code http://www.johngineer.com/blog/?p=648. I just picked his code and modified it.

So what you do now? Take a paper and start drawing what shape you want to see on the scope. You need to draw it on a graph and write down the x,y coordinates and multiply them x10. The more points you have, the more precise will be your image BUT the flickering on the scope will be HIGHER so if you have a lot of points to draw try to use for the low-pass filter 8.2K and 0.047uf instead. To improve your shape also set ON the Persist parameter of the scope

Step 4: About the Code

#define NUM_POINTS 19 // our tree is defined by 19 x/y coord. pairs

Replace 19 with how many points your shape has. For example to create my A i used 16 points.

// x coords for drawing the tree (in rough clockwise order, from bottom)
unsigned char x_points[NUM_POINTS] = { 30,40,50,60,70,90,100,110,120,100,70,60,90,95,55,50};

// y coords unsigned char y_points[NUM_POINTS] = { 30,50,80,100,110,100,80,50,30,30,80,50,50,40,40,30 };

The comments say all. You just input your coords here in the right order (clockwise starting from the bottom).

These coords will give you an A instead of a christmas tree!

Step 5: But You Said a Text Also

Yes this is what i said. And look this is what it came out! I know it's ugly BUT with a little more patience than mine you will came up with a nice and clear text. Just make more points!



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8 Discussions

I acquired an old oscilloscope cleaning out a garage. It's an old 40s or 50s Navy unit. Never been able to figure it out even with the manual. Any hints? I'd like to just read what my house power is doing but I've been scared to hook it to 120/220 volts. Any hints? It does have a neat little green screen though.

4 replies

probably you need a 100x probe to do the! In any case it is always written to the input terminal the maximum voltage you can probe. Look if it's written somewhere near the input terminal, CAT I, II, III etc. if it's more than CAT II, should be fine

I am a Licensed master Electrician by the State of Georgia, Unrestricted, just with very little electronics training. The scope is old tube type Navy issue with all the parts, manuals, and accessories which it originally was supplied with I just never took the time to study it though I did fire it up and managed some cool patterns on the little 4" greed CRT screen. I never ascertained if it would handle higher voltages assuming it was for low volt electronics. Thanks for the tips and if I pull it out I'll begin with a little better understanding thanks to your advice and will advise if I smoke it.
Thanks again,

Thanks for the info.I need to pull it out and refresh on the specs.I've got the manual and all parts it was furnished with I just couldn't decipher the instructions.


buy 100x probes and everything will be ok... I did a mistake it should be written CAT III cause CAT II if i'm not wrong is 400 v peak to peak so connecting directly to 220v will blow up everything

now turn this into a simple aray

and you can call every letter with a command