General resources for Arduino, synths, and more - BleepLabs/Arduino-Light-And-Sound GitHub Wiki
Soldering
Arduino
The Arduino Projects book (Full PDF)
Arduino cookbook (Full pdf)
Both of these are from the earlier days of Arduino but are still very relevant.
Audio DIY and general electronics
Forrest Mims Engineer’s Notebook – Mims’s books are the doorway into DIY electronics for a lot of people since the 70s. He invented the stepped tone generator, aka the atari punk console, one of the most popular noise kits
Circuit Simulator by Paul Falstad. I use this fantastic web tool to simulate simple analog things all the time.
Craig Anderton has written a few classics and is active today.
Electronic Projects for Musicians 40 years old but still has great info (full pdf)
DIY projects for guitarists
Hackaday’s “Books you should read: Basic electronics”
Hackaday’s “Logic Noise” series.
MFOS
Beavis Audio
Nicolas Collins Handmade Electronic Music
Eric Archer
Mutable One of the great eurorack companies and all of their modules are open source
Doepfer A-100 DIY and vactrol filter.
Little-scale
The Lunetta ebook – Lunetta is a collection of CMOS circuits that work together / a kind of DIY synth manifesto.
This “Circuit snippets” page launched so many boutique pedals makers
DC couple interface info
All of the code and schematics for my devices are here in my github of course
General synthesis
Ableton has a great interactive site called learning synths
I think a great way to really learn synthesis to play with modulars. Automatonism is free and has some good guides. VCV rack has thousands of user submitted modules based on real world eurorack
Oscilloscopes
Cheap oscilloscope
The real scope people like is this 1054Z
Windows visual analyzer
Video synthesis
Hardware
The Vidiot a wonderful semi-modular video synth. Not currently in production but should be coming back in 2019. LXV is their premier video synth company but their other gear is pretty advanced and a small setup is very expensive.
3TrinsRGB+1c another great video synthesizer that has audio/cv inputs. Currently available built or as a very time consuming kit. Gieses makes some of the most incredible and absurd AV devices out there.
Glitchart.com makes some interesting circuit bender styles video distortion devices.
The CHA/V is a very simple but fun DIY video synth.
R_e_c_u_r Still in development but is a raspberry pi based video sampler device intended for live performance. Haven't used it yet but looks very promising.
Vintage mixers like those from videonics or panasonic are still available for reasonable prices on ebay. Most projectors still have composite inputs but a vga upscaler like this can be used. Couple this with an old camcorder or digital camera with composite output and you can do some simple color keying and video feedback.
Avoid all video converters that look like this or are new and too cheap to believe. They will output garbage.
So then how do you get analog video into a computer? Unfortunately the only good options are pretty expensive and aren’t even that solid. There are cheaper hacks that work but the quality isn’t great.
Software
This is mostly for mac as that’s the way it is despite their lack of real video hardware
Lumen Video Synthesizer - Roughly based on the 3trins this powerful piece of software can be MIDI controlled and can use syphon for video i/o. $130
GLMxer is a free VJ focused mixer. I haven’t used it but people say it gets the job done. It does have shadertoy support which opens up a lot of possibilities.
VDMX - Very powerful mixer $350 isn’t cheap but it works well and there aren't any other low priced options with its feature set unfortunately
HYDRA - Browser based "live coding networked visuals". Pretty rad and free
Signal Culture has some good resources for all things video art
MAX is an incredibly powerful visual programming language that can be used to make custom video and audio Here’s one of many guides for making a video synth with it.