homemade oscilloscope?

Well, I bought this small B+W tv last year at a junk sale incase I found anything fun to do with it. I really want to make a simple oscilloscope, I just need to figure out how to generate a steady sawtooth wave for the sweep.

What I'm thinking, I need two simple amplifier circuits for the input to scale whatever wave it is to fit on the screen. Positive or negative voltage moves the beam left/right or up/down, so I need to scale that voltage to fit the screen.

Anyways the computer part, I found some programs to generate signals through the sound card, so i attached the left and right output to the verticle and horizontal deflection coils, but the sawtooth wave in the program wasn't good enough to use as a sweep.

Just for playing around purposes, I put sine waves as input. When both have the same frequency and out of phase 90 degrees we should get a circle, and nice pretty shapes for the harmonics. When you parametize the inputs to t as x = sin(t) and y = sin(t+phase), you can graph what you are seeing, pretty cool I guess.

for 2 sine wave inputs of the same frequecy:


for one input the 3rd harmonic of the other, ie one frequency is 3x the other:


The scope isn't going to be used in a practicle sence, but I want to make one that works, it just seems simple, have sweep, have scaled input wave of same frequency as sweep.

Anyone know how I can generate a sawtooth wave for a sweep?
And does anyone know any free function generator programs for PC?

Maybe I'm just weird, but for me its fun at least.

That is awesome!

You will need some sort of hardware interface if you want the computer to work as a function generator. National Instruments makes that sort of thing and software to go with it.

Hey! neat idea dude. If you want some decent signals to mess around with, you may want to consider a software synthesizer. Mainly they are intended for music but you can generate signals with them at normal audio frequencies and LFO frequencies.

Drop by http://www.9barrecordings.co.uk/ and look for the program called "Mass" or look through the directory here: http://synthzone.com/softsyn.htm for something more to your liking.

That's pretty sweet dude. Was that pretty simple, or was it hard? Where could I go to find instructions to do something like that?

EvilAerosolCan said:

That's pretty sweet dude. Was that pretty simple, or was it hard? Where could I go to find instructions to do something like that?

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I just got a job offer today, so that means I can order the parts I need. It's pretty simple, I can post instructions and explain what I am doing if I get it to work. Of course I'd have to include the huge disclaimer about TV's holding a deadly charge even after being unplugged. So if you are not 18 yet, you would have to ask your parents for help.

I think i am ordering from http://www.goldmine-elec-products.com/ unless anyone else has other recommendations. I need to order solar cells for an other project too, so thats my main reason for there.

Is that a good cheap place to order solar cells from?

I ask because I have wanted to make a solar cell unit for a while now.

cyberey66 said:

I just got a job offer today, so that means I can order the parts I need. It's pretty simple, I can post instructions and explain what I am doing if I get it to work. Of course I'd have to include the huge disclaimer about TV's holding a deadly charge even after being unplugged. So if you are not 18 yet, you would have to ask your parents for help.

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That'd be cool. I'm 21 so I don't have to ask my parents.