bisect

a card-shaped video distribution amplifier

this circuit is distributed by UNDERSCORES - an open video hardware label : it is available to purchase - as a pcb, kit or assembled unit - at underscores.shop
the schematic for the circuit can be found here
the pcb gerber files for the lastest version can be found here
interactive BOM is here
consider donating to the underscores project to help us continue creating for the commons

features

active splitting of composite video (no lose in signal strength)
powered from a single 5v supply, ie any usb charger
can be configured to either distribute 1x input to 4x output or two stages of 1x input to 2x output
doubles as a business card for underscores.shop

documentation

this project is fully open-source hardware - all the files required to build it are included in this repo for free. if you have the time and/or skill you can contribute back by collaborating on / testing new designs, improving these docs, making demo videos/other creative content etc. you can also support the project financially by donating directing, or purchasing through the web shop.

depending on whether you are going fully diy or buying an assembled and tested unit, some of the following guides will be relavent to you. the flow would be:

ordering parts

parts sourcing guide (w/ notes on pcb fabracation ) - start here if you are building fully from scatch or have purchased a pcb

i try to source all the parts i can from either:

tayda ; cheaper for common parts like resistors etc, also good for mechanical parts like switches and buttons
mouser ; has lots more options, speciality video ic's, can sometimes cost more (free shipping on orders over 50euros)
other ; ocationally there will be parts which will need to be sourced elsewhere - usaully either aliexpress, ebay or amazon etc...

take a look at the full_bom for this project to see where i am sourcing each part from

import into tayda

go to the tayda quick order and in bottom corner choose add from file
select the file tayda_bom.csv in the BOM folder (you will have to download it first or clone this repo)
after importing select add to cart
NOTE: the minimum value for resistors is 10, so you may need to modify these values to add to cart (or if they are already modified here you will need to see the full_bom for actual part QTY)

import into mouser

go to mouser bom tool and click upload spreadsheet
select the file mouser_bom.csv in this folder (you will have to download it first or clone this repo), then upload my spreadsheet and next
ensure that Mouser Part Number is selected in the dropdown above the first row, then next, process
if everything looks correct can now put add to basket

ordering pcbs

you can support this project by buying individual pcbs from the shop. if you would rather have pcbs fabricated from gerbers directly the file you need is here

i get my pcbs fabricated from jlcpcb - 5 is the minumum order per design
upload the zip file with the add gerber file button
the default settings are mostly fine - set the PCB Qty and PCB Color settings (you can check that the file looks correct with pcb veiwer)
it may be best to combine orders with other pcbs you want to have fab'd since the shipping can cost more than the items - also orginising group buys is a good way to distribute the extra pcbs /costs

i often use jlcpcb because they are reliable, cheap and give you an option of colours. remember though that the cheapest Chinese fab houses are not always the most ethical or environmently friendly - if you can afford it consider supporting local companies.

assembly guide

assembly guide - start here if you have purchased a diy kit

interactive BOM for build guiding

follow this link to view the interactive BOM

general solder advice

remember to heat pad first (2-3seconds), then add solder, then continue to heat (1-2seconds)
Checkout the web-comic soldering is easy for more soldering advice

general order of assembly

in general while assembling i start placing resistors and capacitors first. placing 5 - 10 components at a time and then flipping the board to solder them and trim the legs etc.
next i would do diodes, transistors and ic's - taking care that these are placed in the right direction (using a ic socket can be useful)
finally i place the interface parts - rca jacks, power jack, pots and switches - make sure these have lots of solder on for structural stablity

specific assembly advice

start with the smd ic - then do the passive components, and finally the switch and jacks

operating guide

operating guide - start here if you have purchased an assembled unit

To set up using the circuit plug an active video source into an composite video input and plug a display into an composite video output of the device
Next plug in a 5v center-positive power supply into the 2.1mm barrel jack connector – I like to use a usb wall charger for this
with the source select switch pointing up, the signal on input_1 will be distributed to all four output stages
with the source select switch pointing down the signal on input_1 will be distributed to output_1 and output_2 and the signal on input_2 will be distributed to output_3 and output_4

more info

how the circuit works

[info coming soon]

contributing guide

if you would like to contribute back to these projects in some way but dont know how the best thing (for now) would be to reach out to me directly ( tim@cyberboy666.com or @cyberboy666 on scanlines forum) - i will be happy to help

credits & more info

This circuit is distributed through UNDERSCORES – open video hardware label – visit underscores.shop for more info

The pcb was designed using KICAD , the booklet was created in LibreOffice Draw

Everything from gerbers, cad files, panels and documentation is freely available online and distributed under CC-BY-SA / open-source licenses – help us contribute to the commons !

Ask any questions or start discussions related to this project on the scanlines.xyz forum – an online community space dedicated to diy av / electronic media art

You can contact me directly at tim (at) cyberboy666 (dot) com Please get in touch if you are interested in hosting a workshop !

Thanks to Bastien Lavaud for circuit advice, always. To everyone who has or will contribute ♥♥♥

cyberboy666/_bisect_