Thanks 
Oh I know HOW to connect an LED, I would just like to see the schematic match the project, for completeness, like.
Looking at the arduino code, the LED needs to connect to D13.
The code also implies there is a switch for attenuation connected to D12, but I don’t see that in the schematic or any of the photo’s either. The code does not force any pull-up or down, so is left floating, so not so good
Cheers,
Texy
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I drew the schematic after building the device and next copied the device a few times without looking at the schematic, so I never noticed that the trigger LED is indeed missing from it. The blue LED is meant to signal that a key is pressed. It flashes briefly every time a key is pressed. A green LED with a 10kOhm (or bigger if you have a very bright LED) resistor in series should be connected to D13.
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‘not so good’ does not apply I’m afraid 
I think you may have missed the point. D12 is used in a very clever way in the original schematic, shown below. In the original code it was meant to be used as an output to be set to low whenever attenuation of the input signal was desired. When set as an output the software writes a 0 to it and this effectively puts about 0 V on R3 (connecting it to GND) and thus puts R3 in parallel to R2 and changes the voltage divider (R1, R2 and now R3).
If not so desired it is configured as an input which has a high impedance mode which effectively disconnects one side of R3 from the circuit ergo makes it float and thus it is not a part of the voltage divider anymore (R1 and R2).
In my implementation I was not interested in absolute measurements and not in applying signals of high amplitude that would need attenuation, so I left out this mechanism. The input circuitry was adapted to my use case in my schematic. I left most of the code as it was however, just in case someone building the device would want to restore its original functionality. The code for D12 in this implementation is moot.
But thx for the comment, here is a new version of the schematic.
If you mean the signal input, that would not be desirable. This would put a higher load on the input signal and that is something an oscilloscope should do as little as possible. Also the led is meant to show when it triggers and this can be set to a positive or negative transient in the signal via the scope’s menu, so a led on the input would not be able to do this.
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Thanks for the explanation - the use of D12 in the original context makes sense.
And thanks for the updated schematic sorting the additional LED
So in your version D12 is not used at all. The code I’m looking at in your GitHub page does show D12 configured as an input though, so I’m still a bit perplexed 
Texy
As I said before:
Even if D12 is set to be a digital input in some part of the program, its value is not read. Since the code does not do anything with the input value of D12, it does not bother the working of the oscilloscope.
No problem then
I already had a couple of those displays in my spares bin and just printing off the front panel. I think I may change that to include labelling in a contrasting colour.
Not sure if the small panel size will allow the wording to be clear enough though, but we will see.
Cheers
Texy
Do show the results when you’ve got a working version!
Will do!
Need to buy some more bits though first.
Cheers
Texy
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In my design I use an OLED display with the dimensions shown in the picture below.
Given its width it will fit a eurorack 5HP (i.e. about 25 mm) module nicely, measuring 24.74 mm width (height = 16.90). These fit the STL-files in the repository.
There are however 0.96 inch OLED displays that look very similar but are 26.90 mm wide and 19.26 mm high. They won’t fit the STLs 
.
So check the dimensions of the display when you order it.
I made a small change to the software by adding a DC-zero-ing (DC-offset) item to the menu. The + and - button now allow you to move the signal trace up or down the y-axis which can be handy should it have a DC-component. The chosen setting will be saved in the arduino’s EEPROM thus will be retained when the device is reset or power is interrupted.
Note in this picture the x-axis is switched off.
You can find the software in Scope-O-Matic’s repository.
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Another small change to the software. Now at v2.2. I gave every voltage range its own offset value and made sure they are saved in the EEPROM; furthermore I made the vertical scale selection wrap around, which is much more convenient.
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Thanks for the updating!
I modified the schematics using a rotary encoder to replace 3 buttons.
And changed SMD atmega328p-au to replace arduino nano so that the size of PCB becoming smaller.
The outcome is awesome!
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Nice ! Please show us a picture once you have a finished module.
I think in the near future I will try to adapt the triggering of the module. Some digital synths show one cycle of the waveform being played in the display, which I like very much. I assume they have an easier task to sync to that waveform because they ‘know’ exactly when it is played and with which sample its wave cycle starts. In the present version of Scope-O-Matic that can be tricky to achieve. But there must be algoritms out there that can be of use and I can experiment with. Furthermore the scope now is sort of universal in its setup and the software could be simplified quit a bit if showing one cycle of the waveform is all it needs to be able to do.
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Sure. I tried to use breadboard yesterday. And I am sending to JLCPCB for printing now since I don’t have 3D printer for the front panel…
I will let you know soon 
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Hello guys, sorry I’m new to this arduino synth thing
I wanna build these waveform osciloscope
Can I insert microphone as input?
So it will show waveform as I speak
Or can I insert audio jack output from my computer?
A microphone would need a preamp to get the signal up to synth levels.
Computer sound output would also be lower than synth level, though not by as much, depending what you’re doing you might or might not need to amplify that.
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The oscilloscope has a control mechanism which allows you to choose the input signal amplitude. I’ve never measured what the minimum signal level to show something sensible it needs is.
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Hello
I buy preamp mic kit 1 transsistor, make cardboard enclosure
And still waiting for the main component
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Nice !
If you want to use only a microphone on the oscilloscope, you can simplify the oscilloscope circuit by connecting the slider of the preamps VR1 pot directly to R2 and R3 and get rid of J1, Rv1 and R1 in the oscilloscope circuit. Note that you will then loose the ability to connect other signal sources.
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