[WIP] SNOW - Analog video noise

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After a successful prototyping session yesterday on the VEB,
I came up with a new project “SNOW” (Eurorack module)

The idea is to make a Video Noise Source module .
In the current schematic not everything is connected yet and some values and voltages will be changed later. Work in Progress!

Current features:
analog transistor noise
highpass filter
bias control (very rough state, this will be a trimmer on the back)
gain control (now it is just a attenuator)

Upcoming features:
comparator output (possible with CV control over bias)
more outputs with several filter configurations
…and more

Sunday Noise screenshots:

Schematic:

[VisibleSignals]

Great name for this module!

[giantmecha]

Looks great! Tis the season

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It was already snowing here today, so I did some more work on it.
I had some new ideas about the filter sections. to filter after the amplification, and have several configurations. (lowpass, highpass) I still have to test the values, but it will become something like this.

I might make one simple noise source, and later a bigger extended version
This way I can release the first SNOW for the holidays
The simple one will have 2 pots (gain + comparator threshold), 4 output jacks and maybe a switch
*which noise is routed to the comparator. filtered of white. I have to test if this is interesting enough.
else it may become a jumper setting.

The comparator section is working in the simulation:

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features:
2x offset pot
2x level pot
1x comparator pot
1x comparator source switch (noise1 or noise2)
2x noise out jacks
2x filtered out jacks (2x highpass filters with gain settings)
1x comparator out jack

panel:

pcb:

schematic:

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boards are ordered! (black panel & pcb)
I’ll update the schematic when all is tested and working.

[VisibleSignals]

I’m in! But you knew that

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v2 pcbs are in. I’ll test them and report back here

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test update:
the comparator works very good!
it can go from black starfield to white blizzard, so it lives up to its name!
channel 2 noise looks nice
I have to adjust some values for amplification settings (channel 1)

The values I calculated for filters might be off, so I’m going to test what works better!

quick and dirty screen photos of the comparator out:

[VisibleSignals]

That last image would make a great backdrop, with some keying over the top! Great stuff

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I’m looking into making the comparator voltage controlled.
But that might mean that I need to make 2 sandwitched pcbs, as I probably need to add another opamp for the 5x (1v to 5v) scaling & buffering. - right?
I’ve added a MOD jumper in the v2 pcb. (JU)

I was thinking of making a simple non-voltage controlled version and a bigger one with more features, like 2x CV comparators and more filter outputs.

current schematic:

[VisibleSignals]

Hey Martijn, here are my thoughts:

Sandwiching boards can be a lot of work - you have to work out which signals are going to crossover, and make sure your connectors are lined up and the right way around, and then you then have to lay out the two boards separately (well I haven’t worked out how to do them both together in Eagle yet). But I’ve done a few now (most of my new boards are sandwiched) and it does get easier with practice.

As for adding more functionality to the design - it’s a balancing act and I think sometimes having too many features can detract from the whole idea of a modular format. For example there are those “complete voice” modules in the audio world where there’s an oscillator, filter, VCA, envelope generator, etc etc all in one module. I know some people love that but it seems a bit of a cheat to me, and restrictive because maybe I want to use a different filter etc. Relating that to Snow, maybe all I want is one Snow output, and having multiple outputs is overkill (I could just get two of them if that’s what I wanted). But having said that I haven’t used it yet so I’m not really in a position to comment on what makes sense with it!

I hope this helps, or at least gives you another perspective to think about.

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yes, that is true. I rather like the 8HP format, so normally I try to fit everything in that size (non-stacked).
Featurewise it can just be a interesting source to be processed further.
but the comparator CV control can be really useful and maybe easy to make.
I will think it through some more.
maybe I’ll choose for one noise channel + comparator, maybe with CV. Then you will have 3 outputs and one input, 3 or 4 pots .
we’ll see

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OK testing is done!
Turned out I had a faulty lm6172 in my testbuild. replaced it and now everything works as intended!!

I have an Order thread on the LZX forum, but will post it here when the new pcbs are in.

[VisibleSignals]

Count me in for one, please!

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30 cm of snow here in the Netherlands, snowstorms and going down the slope in an inflatable canoe!

[VisibleSignals]

Most accurate module photo ever!

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lots of pcbs~& panels are ordered!
when they are in, I’ll make an order thread here too

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In this demo I show the 5 different outputs:
1: offset1
2: offset2
3: filtered1
4: filtered2
5: comparator (with switch that selects source 1 or 2)

The offset outputs have 2 pot controls, offset and volume
The filtered outs react to the volume pot.
The comparator output has a level pot and reacts to all pot settings of the selected channel.

[VisibleSignals]

Excellent! Looking forward to trying this out!