- 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
sync_ope is a companion circuit for analog glitch & circuit bent video instruments. it preserves the sync pulses from the original signal and allows for smooth mixing between clean (dry) and distorted (wet) video. preserving the sync pulses means the distorted video is less likely to drop out (blue screen) when sent to analog video decoders such as in projectors, capture cards and digital tvs
- knob for physical control over dry/wet external effect
- cv jack (0-1v) for sequenced control over dry/wet external effect
- external video send & return over rca or 3.5mm jacks
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:
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 - usually 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
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go to the tayda quick order and in bottom corner choose add from file
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select the file tayda_bom.csv in the BOM folder (you will have to download it first or clone this repo)
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after importing select add to cart
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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)
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OPTIONAL: it is a good idea to add some dip-ic sockets and 2.54pin headers/sockets to your tayda order if you dont have them around already
- 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
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 filebutton - 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 - start here if you have purchased a diy kit
follow this link to view the interactive BOM
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remember to heat pad first (2-3seconds), then add solder, then continue to heat (1-2seconds)
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Checkout the web-comic soldering is easy for more soldering advice
for some of the rarer ic's both smd and dip footprints are on the board - if you are assembling yourself you can choose which of these to source (dont place both!)
- for the smd parts i would place and solder these first before doing any of the throughhole parts - please make sure these parts are placed facing downwards as indicated on the silkscreen. you can test the continuity of your solder joints with a multimeter on the pin + one on the corresponding dip pad
- Start by soldering the smallest parts first: resistors, diodes, capacitors and regulators - take note of the direction on the diodes : black bar on component matching black bar on footprint – I place about 10 components in and then solder and clip them
- Next lets do the ic’s/sockets - make sure the direction is correct! place in and fold two corner pins to hold in place, then solder all pins. you can place the ic in now too
- Finally solder in the interface parts: trim_pots & pots, jacks, power barrel. If you are using not using eurorack power supply there is no need to solder anything on j7 (or j3)
There is a total of 4 trimpots on the sync_ope board to calibrate the vertical and horizontal blanking pulses – start by rotating all of them fully clockwise
If you have a two channel oscilloscope with edge trigger you can inspect the incoming video signal on one channel and the blanking pulse on the other (trigger on rising edge of this blanking pulse channel)
- set the scope width to about 1ms - test the edge detect works by probbing pin3 of u7_lm1881 this should lock the scrolling display to vblanking of the incoming video frame
- next hold pulse probe on v_blanking (pin10 of u6_hc4538) - similar to above, the scrolling video should lock over blanking pulse trigger
- starting with top left trim (rv3) allign the rising edge of blanking pulse to the rising edge of video signal by turning rv3 counterclockwise
- next allign falling edge of blanking pulse to falling edge of video signal by turning rv5 counterclockwise
- set scope width to about 10us - test the edge detect works by probing pin1 of u7_lm1881 this should lock the scrolling display to c_blanking of incoming video line
- next hold pulse probe on c_blanking (pin10 of u5_hc4538) - similar to above, the scrolling video should lock over blanking pulse trigger
- starting with top right trim (rv2) allign the rising edge of blanking pulse to the rising edge of video signal by turning rv2 counterclockwise
- next allign falling edge of blanking pulse to falling edge of video signal by turning rv4 counterclockwise
start with all trim pots clockwise . plug in an effect and have sync_ope mix knob clockwise (wet): notice the square outline of the screen with the effect and the outer parts that are without - this is what we are trying to fill in:
starting v_blanking with top left - rv3 and then to rv5:
- watching top of screen turn rv3 counterclockwise until effect alligns with viewing area
- watching bottom of screen turn rv5 counterclockwise until effect alligns with viewing area
now c_blanking with top right - rv2 then rv4:
- watching left of screen turn rv2 counterclockwise until effect alligns with viewing area
- watching right of screen turn rv4 counterclockwise until effect alligns with viewing area
operating guide - start here if you have purchased an assembled unit
- power the unit via the barrel jack with 12v_dc adapter - alternatively you can power it from the eurorack header or +-5v with the side power pins
- plug a composite video source (eg output from a camcorder) into the top left VIDEO_IN jack -> the middle led should light up when a video source input is detected
- plug a composite video display (eg an old tv or easycap capture card) into the top right VIDEO_OUT jack
- now with mix knob rotated fully anti-clockwise your source video should be passing through to the display
- plug one of the VIDEO_SEND jacks into the input of your external processing device
- plug one of the VIDEO_RETURN jacks into the output of your external processing device
- now with the mix knob rotated fully clockwise your source video should pass through the external effect device - but with stable sync pulses !
- if you have the gear for it you can sequence this mix knob using the cv jack above it - only the range 0-1v will respond - dont send it negative voltage.
to calibrate the blanking intervals between pal and ntsc there are (rough) markings on the pcb to help you. for any given trimpot:
- rotate it all the way anticlockwise. from this position take the part of cross pointing south-west (7-8oclock) as reference and rotate clockwise until this reference is lined up with the marking (n for ntsc, p for pal)
- if you have an oscilloscope you can calibrate more precisely by connecting the scope inputs to pins 10 of U6 and 10 of U5
- you can also try to calibrate blanking by eye - setting it roughly to the markers and then moving the trimpots slightly to see what happens.
[pic coming soon]
how the circuit works
[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
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 Gael Jaton for sharing your designs and knowledge. to Bastien Lavaud for circuit advice, always. To Guergana Tzatchkova for booklet design inspiration. To Ben Caldwell for project advice. To everyone who has or will contribute ♥♥♥