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My DIY Audio Scope so far (will update)

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barfle

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Actually buried somewhere in the forums within, oh, the couple of years was a project that did that. It was technically successful but aesthetically mediocre. The difference being that a CRT phosphor has a measurable decay time; the time it takes for a spot to fade out after the spot has moved elsewhere. That makes the CRT version much smoother & easier to interpret the display. Discussion was made on how to add artificial decay time to the software project & it fizzled out at that point.


Now if you want something that is 2 ch but is so powerful it has been known to cause Royal Houses of Europe to crumble. The Atari MusicVision:


Yes I have one. I've never hooked it up to my 8' screen for fear of causing cerebral hemorrhage.
I have one also. I modified mine so it outputs composite video instead of CH3 RF. Interestingly, it fills my 1080 screen, but I never figured out why. Great fun with disco and its heavy bass line. 😀
 

doity

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I have one also. I modified mine so it outputs composite video instead of CH3 RF. Interestingly, it fills my 1080 screen, but I never figured out why. Great fun with disco and its heavy bass line. 😀

Would love to see it since I missed that long, lost post. I have seen some digital oscilloscopes online for computer audio but was not impressed. Ain’t nothing like the real thing baby!
 

Wurly1

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Really cool I've watched the video more than once. I like the "4" in the middle & I don't think the widescreen display is a problem at all. Did you say this uses 6" LED display? That's pretty big you can see that from across the room. I am also curious what music and decode format did you use for the YT video?

About a hundred years ago I built something similar but smaller. Actually it was part of a quadraphonic input/output control center:
View attachment 53599

You can see the rectangular display window where the LED meters went. I had to go to a machine shop to get the hole cut out. I don't have the skills or tools to make it look professional. Like in your project the 'tronics is sometimes the easy part, making an enclosure that looks good & suits your purposes is the hard part.

Here's the little LED board that sat inside the tinted window:
View attachment 53600

Notice that the LED modules on the left side are inverted. They were red/green with green being at the center. The board behind was just the input buffer board with multi-turn trimpots so I could calibrate the level detection precisely. Of course it is very rectangular to fit the window. Doing it today (which you're kinda getting me revved up to do) I would do the layout more as you have done.
Those LED modules were sold seperately at Radio-Shack in the end of the 70's.
 

Soundfield

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That’s really interesting Doity, and quite a co-incidence – I was toying with a design for a similar thing a few months back! I was inspired by those pseudo ‘scope displays that Pioneer put on their quad receivers. Like Sonik said, there are loads of VU boards available either as built modules or as DIY kits you can use for this sort of thing. I used a kit as it was then easier to change the mulitcoloured LEDS to normally fitted to such things to large square green LEDS more suited to mimicking a scope:

modified VU pcb.JPG


I tried a couple out as shown here with a stereo signal where I’m also experimenting with making a scope style graticule:

LED Level Indicator on test.JPG


The next stage was to make another two boards and arrange all four in a suitable housing (this was a modified deep picture frame, shown here without the graticule and glass):

quad vu display frame.JPG


But then, as so often happens (!) I lost interest and moved on to another project so it’s not gone any further. I might get back to it but the real reason I haven’t got much enthusiasm for it now is that it’s not a proper vector-scope display and so doesn’t tell you anything about what’s going on in positional terms between the four cardinal points. You also need to take phase into account to do that of course. So I am thinking about doing this as an addressable x-y array of LEDS. Whether this one gets any further than the prototype stage is, given my track record, problematic!!
 

Sonik Wiz

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not my area of expertise, not even near it but I wonder if this is a way in?

I see the actual scope portion is not cheap
Yuppers if you just google USB oscilloscope you'll find a wide range both in features & price, kit or assembled, and some that have their own phone size screens built in. It is important to choose one that show Lissajous tracings where both the X & Y axis can be controlled by the input. Since this simulates a CRT scope where the deflection plates are vertical & horizontal you would also need a rotational matrix at the front end to convert the 4 ch signals to work with this.
 

Sonik Wiz

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That’s really interesting Doity, and quite a co-incidence – I was toying with a design for a similar thing a few months back! I was inspired by those pseudo ‘scope displays that Pioneer put on their quad receivers. Like Sonik said, there are loads of VU boards available either as built modules or as DIY kits you can use for this sort of thing. I used a kit as it was then easier to change the mulitcoloured LEDS to normally fitted to such things to large square green LEDS more suited to mimicking a scope:

View attachment 53985

I tried a couple out as shown here with a stereo signal where I’m also experimenting with making a scope style graticule:

View attachment 53986

The next stage was to make another two boards and arrange all four in a suitable housing (this was a modified deep picture frame, shown here without the graticule and glass):

View attachment 53987

But then, as so often happens (!) I lost interest and moved on to another project so it’s not gone any further. I might get back to it but the real reason I haven’t got much enthusiasm for it now is that it’s not a proper vector-scope display and so doesn’t tell you anything about what’s going on in positional terms between the four cardinal points. You also need to take phase into account to do that of course. So I am thinking about doing this as an addressable x-y array of LEDS. Whether this one gets any further than the prototype stage is, given my track record, problematic!!
I really like that. Good 'ol Velleman kits! I think it would be worth persuing it looks like your almost done. CRT quad scopes are better for showing non-coherent sound than LED meters but LED VU meters are more readable if you are looking closer at amplitude levels. Hey! It's a VU meter!
 

doity

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That’s really interesting Doity, and quite a co-incidence – I was toying with a design for a similar thing a few months back! I was inspired by those pseudo ‘scope displays that Pioneer put on their quad receivers. Like Sonik said, there are loads of VU boards available either as built modules or as DIY kits you can use for this sort of thing. I used a kit as it was then easier to change the mulitcoloured LEDS to normally fitted to such things to large square green LEDS more suited to mimicking a scope:

But then, as so often happens (!) I lost interest and moved on to another project so it’s not gone any further. I might get back to it but the real reason I haven’t got much enthusiasm for it now is that it’s not a proper vector-scope display and so doesn’t tell you anything about what’s going on in positional terms between the four cardinal points. You also need to take phase into account to do that of course. So I am thinking about doing this as an addressable x-y array of LEDS. Whether this one gets any further than the prototype stage is, given my track record, problematic!!
Wow, I love that design. Very ingenious. Well I had no illusions that my ‘scope’ was nothing more than just a way to see that all channels are working and to look at some flashing lights in the meantime. And truthfully most people that used these things probably just wanted some cool lights to groove out on or some similar 1970’s jargon 🙂

I hope that you can finish the project and let us see the results. I love the picture frame idea. I was thinking of duplicating the grid on the Pioneer scopes by copying and magnifying the image and possibly having a nylon decal(?) done up that would at least look like the real deal but gave up on that idea.

I do have one of those Radio Shack LED power meters that hook up to the speaker connection that are true meters in the sense of measuring wattage. Maybe I will hook up mine to the remote speaker connection and see if I can run all simultaneously? Never enough flashing lights 👍
 

doity

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But wait......there’s more! I mentioned earlier that I wanted to replicate the grid of the Pioneer receivers with the fake scopes but gave up on that idea. So I decided to buy some pinstripe tape and do ‘something’. I eventually decided to try and replicate the look of the Marantz 4400 scope.

The markings mean absolutely nothing, but hey it looks like they do so that is all that counts right? 🙂

I am officially done now as there is no way to improve on it in it’s current form.
 

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Sonik Wiz

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But wait......there’s more! I mentioned earlier that I wanted to replicate the grid of the Pioneer receivers with the fake scopes but gave up on that idea. So I decided to buy some pinstripe tape and do ‘something’. I eventually decided to try and replicate the look of the Marantz 4400 scope.

The markings mean absolutely nothing, but hey it looks like they do so that is all that counts right? 🙂

I am officially done now as there is no way to improve on it in it’s current form.
Looks good! You must have a very steady hand to apply that tape so perfectly.
 

doity

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OK I lied! I was not totally done obsessing over my scope as I kind of regretted not putting some kind of lighted ‘4’ digit in the center of the scope. By the time I thought about it I had no space in there to work with. So I ordered some glow in the dark vinyl and had to compromise, though it did turn out Ok. I even used a square of colored background to give some contast to all of the black and white. Actually I stole the idea from those Pioneer receivers (?) that have the cool 2/4 displays.

The lights from the receiver kind of wash out the glow in the dark when it is on but it was a nice thought anyway. You can see what it looks like below in a totally dark room so it does work, but not like I had imagined.

Has anyone else gone ahead and try something similar since I initially posted.....building a scope display that is? I know that a couple people had either started something or were gonna go ahead and try it. Just curious.


56399F02-5514-4A20-95CA-C9F84FE285E0.jpeg

0D58D278-6FBF-4222-A127-03AC341C9D0F.jpeg
 

malcolmlear

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How about this module, it has 6 analog inputs and easy to program any visual style output.

 

doity

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How about this module, it has 6 analog inputs and easy to program any visual style output.


Malcolm, I looked at this and that is pretty badass and fairly cheap also. It looks like you need the kit though to program it, but still fairly affordable for what it does. In retrospect I should had used a single Nixie tube to do what I needed. That would had given it a real vintage look also.

As far as OLED technology, about 7 years ago or so I bought a OLED watch from Japan for quite a bit of money as they were not cheap. Thing was that once the battery went out you couldn’t replace it for some reason and that was it. Still wish I had it. The gadget freak in me is now wanting one of those modules for sure. Look what you started 😀.
 

Sonik Wiz

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Malcolm, I looked at this and that is pretty badass and fairly cheap also. It looks like you need the kit though to program it, but still fairly affordable for what it does. In retrospect I should had used a single Nixie tube to do what I needed. That would had given it a real vintage look also.

As far as OLED technology, about 7 years ago or so I bought a OLED watch from Japan for quite a bit of money as they were not cheap. Thing was that once the battery went out you couldn’t replace it for some reason and that was it. Still wish I had it. The gadget freak in me is now wanting one of those modules for sure. Look what you started 😀.
The MicroView would look pretty slick built into OEM gear. But at only ~1" square it really is micro. There are 10x10 LED dot matrix displays that are 50% larger but still only 1.5" small. With those you wouldn't need an Arduino just a couple of LM3914/5/6 chips... one connected as source & the other connected as drain to address the rows & columns. IIRC there were some DIY articles using this to make a "solid state Oscilloscope".

I like your larger display & the "4" looks cool. For my set up a 5" active area display would be optimum. Now ya got me thinking about it again.
 

Soundfield

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With those you wouldn't need an Arduino just a couple of LM3914/5/6 chips... one connected as source & the other connected as drain to address the rows & columns.
You can't do that directly can you ? - I didn't think they had true open collector outputs but were constant current sources.
 

Sonik Wiz

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You can't do that directly can you ? - I didn't think they had true open collector outputs but were constant current sources.
You are correct. For source you can connect direct. For drain you would connect to a transistor (FET array?) which would go to ground.

I just checked & there are dozens of various DIY LED O'scope plans out ther. All I've seen so far try to mimic the horizintal sweep of a real scope. Don't really need that for this application.
 

Soundfield

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You are correct. For source you can connect direct. For drain you would connect to a transistor (FET array?) which would go to ground.
Or you could use opto-couplers which would be a simple I/F to the LED outputs of those bargraph chips. Although come to think about it you could only use the chips in dot mode in this application otherwise you'd get a very strange display indeed (and need a lot of current).
 
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