Category: shop

a new circuit has been added to the underscores catalog : _rotary_ – a voltage controlled fader module for V-4EX, V-8, and V-4 video mixers

background

a few years ago while i was visiting berlin Gilbert Sinnott (autr) and i were inspecting the cv mod that had been installed by a previous owner on my Roland V4 video mixer:

you can see the 3.5mm cv jack and a toggle select switch here on the front of the mixer. Inside can just be made out some perf board with protection diodes.

these series of mixers (Roland V8 and V4EX also) have removable T-bars – this is so the user can select whether they want to have a vertical or horizontal T-bar. it also allows for swapping the T-bar interface like for example with this offical Roland CrossFader Module:

prototype iterations

We started thinking about how this CV mod with protection diodes and a select toggle switch could be integrated into a swappable t-bar module…

after some testing and iterations the passive mod was upgraded to an active opamp circuit, allowing for:

• cv gain control over ranges 0-1v up to 0-5v
• simultaneous cv and manual fader position / cv offset

finally we decided to also include a simple envelope follower circuit allowing for audio reactive crossfader control – with this comes the envelope/bypass toggle switch and a shape knob:

this circuit uses TLV237X opamps – these are 3-MHz rail-to-rail opamp available in dip packages (video rate is not needed since limited by the frame rate of the digital video mixers)

demo video

you can see a full install / walk-through of this circuit in the _rotary_ circuit demo video:

it is in stock now in the shop as kit or assembled unit (pcb+panels coming soon)

once again i am closing the shop for the summer (southern hemisphere) while i am traveling / working some festivals in Aotearoa.

any orders placed after November 16th will be processed from the 20th of January 2025. i will also be restocking some popular circuits, releasing a new product and (finally) adding some panel / enclosure options for a number of existing circuits. join the email list to stay in the loop!

if you are in Aotearoa you can catch me:

• performing experimental visuals on the historic Hollywood Theater Avondale cinema screen as part of OUTLIER FESTIVAL in Tāmaki Makaurau,
• building and running the dojo stage tv wall installation and curating films at TWISTED FREQUENCY FESTIVAL in Takaka,
• and potentially hosting a special TRASHPALACE film event in Te Whanganui-a-Tara

thanks for your continued support this year – i look forward to sharing some new projects with you in 2025 – stay safe out there!

this post is to announce the release of another new underscores product – the artnet_led_mapper – an open-source cross-platform application for creating addressable led installations

its the second software app we have released (after the similar tv_wall_mapper earlier this month) and the final in a series of open-source tools for video installation work based on my own art practice from the last year

project overview

artnet_led_mapper is software designed to help you to map arbitrary video onto an addressable led strip canvas – in this example (from the project demo video) i have arranged the leds into a low resolution led wall:

but you can map your video source on to any number of creative and abstract stage designs as shown here from the lateral movement club nights that inspired this project:

the software takes a video source (you can use webcams or external capture cards or video sent over NDI) and uses your user defined mapping to output art-net – a network dmx lighting protocol. this is combined with a hardware led controller to control the array of led pixels.

we recommend using our open-source hardware solution the lateral_led_controller although this software should work with any art-net compatible controllers

watch the full video where i demonstrate setting up the mapping for the led wall example:

background and motivation

as mentioned above this project was inspired by the installation work i did with lateral movement – a semi-irregular club night showcasing left-field & experimental dance music and light – you can find out more about the background to this in the artist talk i gave on it WORKS IN PROGRESS 04:

we ended up using touch designer to create the custom patches for this installation since my collaborators had a bit of experience in this. it worked well but was quite complex. also i needed to borrow their windows laptop to test the hardware on since i couldnt run it on my linux computer.

at this point i was already building a similar single purpose mapping application for tv wall installations and thought it could be worth forking that to do the same thing for led installations

resolume is also capable of outputting artnet for these kind of led installations. i will repeat the exact same points that i listed on the tv_wall_mapper blog post as to why i was motivated to create this alternative solution (since they all still apply to this app also)

we are happy to provide another light-weight, open source and cross-platform alternative to making video-art installations and exploring new ways to work with video and light!

same as the tv_wall_mapper this app is open source and available to compile yourself for free – you can also make a sliding scale donation (between 10-100euros) to support this work and gain access to pre-compiled versions that should run out of the box!

a new circuit has been added to the underscores catalog – the lateral_led_controller – a hardware network interface for addressable led installations

this is another release in the series of open-source tools for video installation work i have been developing and is a companion to the artnet_led_mapper software that is also being released today.

the lateral_led_controller converts art-net sent over wired ethernet into the protocol used for addressable leds. it can be combined with mapping software to send arbitrary video onto an led strip canvas:

this circuit is based on the custom hardware i designed for lateral movement – a semi-irregular club night showcasing left-field & experimental dance music and light

i made a demo video showing how to use this controller to set up an addressable led installation like these – you can check it out here:

addressable leds

its currently compatible with the two main families of addressable led strips (but more can easily be added via firmware updates):

• the WS281X (neopixel) which is a cheap but slow single wire protocol, which the controller can support up to 8 parallel outputs

• the APA102 (dotstar) which is a faster two wire protocol – a single data line plus clock line can control up to the 2000 recommended pixels

motivation

this product is a bit different from the video instruments we usually focus on for underscores releases – unlike those, there are many led controllers already on the market. however when researching options for our club nights (just over a year ago now) we didnt find anything suitable in our price range.

all the existing led controllers we looked at were either:

• very expensive professional gear
• only supported a couple of universes (ie <500 pixels)
• designed for home use with only wifi options ( we need a wired ethernet connection for use in a crowded venue)

i wanted to design a controller specifically made for the kind of video-art installation work we were doing

new alternatives ?

interestingly enough there does appear to be some more affordable options for generic wired ethernet led controllers coming out of china these days such as this H807SA (and a few others i could see on ali)

i have not tested any of these myself so do not know how/if they work – i would be curious to hear from anyone who has however!

regardless i believe it is still worth releasing open source and artist made alternatives where possible. the main advantage to using an open source controller is that we can fine-tune it to our specific needs rather than relying on a black box – this also future proofs us – if a better led strip with a new protocol comes out we can update the open-source firmware and continue using our existing hardware.

circuit modules in the design

one interesting thing about this hardware design is that it is made up of a few existing circuit modules. besides the WT32-ETH01 micro-controller there is also the MP1584EN_5v_stepdown module and the WeMos_CH340G_USB_to_SERIAL module:

the main advantage of this approach is that we can use smd parts while still keeping the project diy friendly. also sometimes it works out cheaper to source these premade modules than the individual parts since they are purchased and assembled in large batches and then resold. however it can feel more “hacky” and make sourcing parts for the project harder in the long term (if these particular modules become less available)

this project started as an adaption from a in-house one-off solution i designed and the use of these modules in it reflects this – if it proves to be popular enough and useful to others outside of this i may consider a future revision which is made up directly from the smd parts it needed – time will tell!

the local web interface

another cool feature of this controller is the local web interface for easily configuring network / led settings:

by joining a wifi access-point created by the controller we can access all the settings required on our computer / phone

i found this to be a nice way to configure a micro-controller without needing to edit code or dive deep into a tiny menu – im excited to use this approach again for other micro-controller projects i work on!

im happy to announce the launch of a new product for underscores : the tv_wall_mapper – an open-source cross-platform application for creating synchronized tv wall installations

although many underscores projects have software components to them this is the first purely software application we have released – its also the first of a series of open-source tools for video installation work that i have been working on inspired by my own art practice over the last year.

project overview

tv_wall_mapper is a software designed to help you create a synchronized tv wall effect – where many tvs are installed together to output different portions of a single cohesive video feed.

there are a few different hardware options (outlined in the project readme) that this app can work with to achieve this effect – perhaps the best being the use of off-the-shelf tv_wall_controllers such as these:

inspiration and motivation

this project was inspired by a recycled tv wall installation we built for the dojo stage at Twisted Frequency Festival 23/24 – you can hear a bit more about this project in my WORKS IN PROGRESS 02 artist talk:

under the hood the video mapping is done using openframeworks + some glsl shaders (both things i had some experience writing for other projects)

it is possible to achieve this effect with existing projection mapping software – for our installation originally we were using resolume with the hardware controller to achieve this.

the main reason i have taken the time to polish and publish this little diy alternative:

• i use pop_os as my daily driver and wanted an app that could run on this (which resolume does not)
• resolume is proprietary and expensive – it is important to have open and accessible alternative tools for artists
• building on the unix philosophy of creating software tools that are designed to do one thing well – this app aims to be simple and lightweight (you can always “pipe” video from other apps using NDI )
• a nice side-effect of having a light-weight cross-compatible app is we can also run it on single board computers such as raspberry pi’s – commonly used for installation work

compared with hardware releases which are relatively easy to price (taking into account the cost of parts, labor, creative work and similar products on market ) it is harder to know how to price software -especially “small specific task” apps such as these. the code is open source and available via the github for anyone to compile for free. i have decided to also offer pre-compiled versions of these apps via the underscores shop for a small donation (a sliding scale between $10-100) hopefully this strikes a balance between making it accessible to those without the funds and also sustainable to invest our time into.

this kind of release is new for us and im very happy to hear any thoughts or feedback from those reading about it here

i am happy to announce that the two_point_one_colorizer circuit based on Rob Schafer’s design is in stock now!

it is currently available as a diy kit or fully assembled and tested unit – bare pcbs will also be in stock soon (when my next pcb order comes in)

you can find all the source – schematics, gerbers and documentation on the project github page

theres some more written info about this circuit in an earlier post i made here

im not quite ready to stock front-panels in the shop yet – partially because im still working on how to expose interface parts like the slide switches that sit below the panel – however panel blueprints are available as files for those who want to diy some.

i will make a dedicated intro/demo video for this circuit some time in the coming month – in the meantime however you can see a demo of it in action in this artist talk:

finally i wanted to share some images captured from this circuit (these are all directly into a cheap easycap capture card) – in particular some examples of when it glitches / breaks (due to providing out of spec video):

some of these were captured while i was experimenting with different kinds of monostables to generate the colour subcarrier frequencies – you can see where the oscillations are too slow to be interpreted as colour as start to be interpreted as changes in brightness. i recommend using ic sockets for the parts U9 & U10 so you can experiment with this also!