A note in advance: Please first check which firmware version is running on your Synkino. Go to “Extras” in the main menu and then to “Version”. If your Synkino still runs software version 1.0, you have to send it to me again so that I can update it. Version 1.0 has a number of severe bugs, which make it extremely difficult to run, and unfortunately an update via Arduino IDE with this software version is not possible without further ado.

The following instructions are valid from version 1.1 or newer.

You need:

  • a 9 V battery (or something else that delivers 6 to 13 volts, 6 AA batteries for example would definitely last longer than a single battery)
  • a microSDHC memory card (i.e. 32GB or less. 16 GB is perfectly sufficient, even for the largest imaginable movie collection! Synkino is not coping well with larger memory cards (SDXC type) at this time.
  • An active loudspeaker, a jack-cinch cable or, if not enough, just headphones to be able to listen to Synkino. The 3.5mm jack socket at the left of the microSD card serves this purpose. The 3.5mm jack is at the top next to the microSD card is intended for that.

Quick start instructions – configuration

  • Connect Synkino to the battery (bottom of the board). Make sure the polarity is right. Wrong polarity doesn’t cuase damage, but Synkino won’t work.
  • Press the Power button.
  • After a while, you will be asked to enter a projector name (“Select Projector Name”). This only happens if you haven’t configured a projector yet. You can change, add or delete projector configurations at any time, but you must have at least one:
  • Use the rotary knob to select the letters/numbers and press to move to the next digit. There are two special characters in the list: Space and “Delete Last.”
  • When you’re done, press the knob for a few seconds.
  • In the next step you will be asked how many segments the wingtip of your projector has. Choose “2” for now, you’ll see later why.
  • You will now be prompted to enter the “Start Mark Offset”. This is the distance (in frames) between the film gate and the start mark detector. Dial in 50 for now.
  • The next values, “Proportional,” “Integral” and “Derivative,” are parameters that allow you to accurately adjust the way Synkino responds to changes in projection speed. Take the default values for now (8, 3 and 1). It will probably never be necessary to change these, but who knows.
  • You will now be taken to the main menu. This is where Synkino will welcome you into the future. Press the small “Reset” button at the bottom right, and you should return to the main menu.

That’s it for now with software control! Next step:

Preparing the microSD card

Take your microSD card and put it in your computer’s card reader. I recommend formatting new microSD cards for the first time, as they often contain junk software that takes up space and could confuse Synkino.

To format the card, I recommend not using your computer’s disk utilities. They are often not fully compliant with the SD card specification, so download the free official SD card tools and format the card with them. You only have to do that once, so it’s no big deal.

Synkino doesn’t run an operating system like Linux or Windows that brings a comprehensive driver for file systems. Synkino has only 4 KB (!) RAM and therefore operate the memory card a little more directly. Therefore it has to be formatted exactly as Synkino expects.

Once the microSD card is formatted, you can copy the soundtracks of your movies to the card. Synkino works exclusively with audio files in Ogg/Vorbis format. This file format compresses the files as efficiently as AAC, so better than MP3, but is free of software licenses and very “unambiguous”. Ogg files can be generated on any computer with free tools within seconds.

For the Mac, a simple program is Audio Converter Lite, it’s free and has no noticeable limitations. At the beginning it asks for an email address, but you can just skip this step. For Windows or Linux, I recommend Audacity.

Theoretically Synkino can also read other file formats like MP4, MP3, AAC, WMA etc.. However, their specifications have a lot of room for interpretation and often also allow extensions that cause Synkino to stumble. Since it is impossible for me to test Synkino with every conceivable file, file types other than “.ogg” are currently not supported. This prevents a lot of problems.

When exporting to the ogg format, only three settings are actually important:

  • Stereo (At least I didn’t test Synkino with mono files)
  • Set sampling rate to 44.1 kHz (48 kHz allow almost no room for speed corrections upwards!)
  • Do not set the quality above 80% (or “8” or “0.8”) or “384 kbps”

For sound in CD quality, 70% or approx. 256 kbps is perfectly sufficient.

Once you have moved the converted ogg file to the root directory of your microSD card, rename it to “001-18.ogg.” The first number is the title number, the second number (here 18) corresponds to the frame rate of your film. It can be any whole number from 12 to 25. Thus Synkino knows that it should play exactly one second of sound during 18 frames.

The next files should follow this scheme, such as “002-24.ogg,” “003-18.ogg,” etc. It makes sense to write the number awarded on the can of the respective film, so that you know later that “Holiday in Hamburg 1982” needs the soundtrack number 007. Makes sense, doesn’t it?

Now you eject the microSD card and insert it into the card reader of your Synkino. The contacts have to point downwards, the card only fits if inserted correctly. Be sure to push the card until you hear the click. eject it, simply press the card again and there will be another click. Like a ballpoint pen.

Time for a quick test run!

Synkino (re-)start. This is important after installing a new µSD card, as Synkino will write a tiny firmware file to the µSD card that it needs to initialize. Don’t worry if you accidentally delete this file. Synkino will simply recreate it.

Select “Select Track” in the main menu by pressing the knob. You will now see a “001” in large letters. Use the knob to select the audio file you want. Probably that’s just 001 right now.

After a few seconds at most, Synkino will display “Waiting for Film to Start”. Sadly, because Synkino doesn’t see your projector yet, it won’t start playback. But if you press the knob again, you will find “Manual Start” option. This option can be useful if your movie doesn’t have a white leader or if you want to start by starting mark for whatever reason. Just give it a try; You should see “0:00:00” on display.

If you are disappointed that the seconds are not progressing, rest assured: Synkino is doing just the right thing, because it thinks your projector is stopped, so the sound stops too!

Now you need to wire up a few simple things.

  • Connect the 3.5mm jack to your amplifier, active speaker or headphones.
  • Plug the cables of the two “eyes” into the 2.5mm jacks in the upper left corner.
  • Power up Synkino. If you move your finger in front of the small black chip on the PCB of the eye, you’ll see a red LED above the display turn on. This indicates that the eye is detecting “reflection” Both eyes have such an LED on the board.
  • Now you thread the beginning of a film into your projector and stop it.
  • Mount the “start mark” eye (upper left socket) somewhere on your projector where it is near the film. A good place is where the film runs into the projector. Make sure the eye doesn’t touch the film (to avoid scratches), but isn’t much more than 10mm away from the film either. Temporarily, simply use a few strips of tape to attach the eye and cable. You can attach it more sustainably later if you want.
Can also well be mounted in the projector, preferably close to the film entry.
  • Attach the “Impulse” eye (the socket to the right of the other one) so that it can see how the projector is running. A good place to do this is often the projector’s motor shaft, which usually makes exactly one revolution per frame. Since handwheels are usually black, you can use a white tape to let Synkino see the movement. (You can also mount it on the actual shutter blade or use your own sensors, but that’s another topic and for later). Again, you should use tape first until everything works smoothly.

The Beaulieu 708 Projetor apparently has a knurled aluminium handwheel, which is seen by Synkino as very many impulses. Here, it helps to wrap the hand wheel with some black tape and paint or stick two white dots on it.

This is enough to reliably observe the engine shaft.
  • Start the projector now! The LED next to the “Impulse” jack should flicker. It might actually flicker so fast you can’t see it, so use the hand wheel to make sure Synkino sees the movement.

You’re almost ready, just one more step!

Two things are important to start the sound safely in sync with the movie:

  • Use reflective (white) leader. A white leader works best, green is okay too, but black film doesn’t work. Besides, transparent film doesn’t work well either.
  • Thread a piece of white leader into your projector until it passes the image window and then stop the projector. You need to save the distance between the start mark detector and the image window in your projector configuration. This is very easy:
  • Make sure the leader is long enough for the start mark detector to see the leader.
  • Remove the lens from the projector.
  • Using a slide marker, draw two marks on the film: one through the film gate and one where the eye is placed.
Without the lens, the film can be marked easily in the gate
  • Rewind to get the leader out of the projector again.
  • Count the sprocket holes between the two markings and write down the distance.

This is the “Start Mark Offset” that must be stored in the configuration of your projector. So go to the main menu and select “Projector” → “Edit” → [Your projector].

Continue through “Projector Name” and “Shutter Blades” until you reach “Start Mark Offset”. Enter the counted value and then press the button until you’re back in the main menu.

That’s it!

Time for a first synchronous projection.

  • Take the movie you want to show.
  • Insert the leader into your projector and stop the projector when the film is fully threaded.
  • Start Synkino.
  • Select the audio file number.
  • Once the file is loaded, you can start the projector.

Enjoy the movie!

If you stop the projector, the sound will also stop. If you restart the projector, the sound will continue to play. If you change the projection speed, the audio playback will follow the projector’s tempo — within a certain range: Synkino can control the speed of an audio file from 17-116%, i.e. from almost six times slower to 16% too fast.

Synkino displays a standing “SYNC” icon on the display while playback is in sync. If the sync is lost, the icon will start flashing and indicate how far the sound and image have shifted until the sound has picked up again.

Even if Synkino can’t regulate anymore, for example because the projector is running at 24 frames per second instead of 18 (which is 33% too fast), Synkino will always readjust. So just turn the projector down, the synchronization will snap in within a few seconds.

What Synkino can’t do is understand reverse projection. Running backward looks the same for Synkino as running forward. So if you rewind a scene during the show, Synkino loses synchronization.

Manual correction

If you ever find that the movie and audio are out of sync, even though the SYNC icon is on, you can correct that manually. This can happen if, for example, you had to cut the film and lost one or two frames. Another possible reason is that your start mark detector has been moved or the loop size in your projector is not always the same.

To correct this during playback, simply press the knob and rotate it to set the exact synchronization point. The SYNC icon stops flashing as soon as the new synchronization point is reached.

Any questions? Just leave a comment.

Roll the film!

Continuous operation

After a complete audio file has been played, Synkino returns to the title selection menu. If you screen several films, coupled and separated with white leader, the projector can now be stopped, the next soundtrack selected, and synchronous playback restarted.

To get from the title selection menu to the main menu, you simply have to select Title 000.

Sampling rate and control range

Sampling rateControl range
48 kHz17-107%
44.1 kHz17-116%
32 kHz17-159%
22.05 kHz17-227%

The sampling rate determines how many values per second describe the audio signal. The usual value is 44.1 kHz, this rate is also used on CDs, for example. The control range of the Synkino, i.e. the extent to which it can adjust the playback speed of a projector that is running too fast, depends on the sampling rate. The values shown in the table apply.


Your Synkino comes with eight “eyes.” Two of them are already plugged into the cables. By the way, the little PCBs have to be plugged in with correct orientation to function. If connected the wrong way round, nothing bad happens, the eye just won’t work. The respective control LED next to the socket shows you whether you have connected it the right way round: It lights up when you approach the eye with your finger, for example.

One angled and one “straight” sensor

In total, you will find:

  • 2 angled sensors
  • 2 straight sensors
  • 2 sensor PCBs without soldered pin headers
  • 2 empty sensor PCBs

You should get a whole bunch of projectors equipped with that.

If you want to build or connect your own sensors, the enclosed schematic will help you. In short: Two of the three lines are a 5V power supply, if you need it (for example with fork light barriers), the middle line supplies the clock as TTL signal. The delivered pulse signal further runs through a low pass and is processed by two Schmitt triggers. The start mark sensor manages with one.

On the jack plug side the tip is occupied with the pulse, the middle ring supplies plus, the shaft of the plug supplies minus of the 5V.


By the way, the current intake during playback is 50-150 mA. So the battery should last many hours. After 10 minutes of inactivity, Synkino automatically switches itself off completely so that the battery is not accidentally drained. You can also switch off Synkino yourself via the menu.

By the way, switched off also means really switched off: No standby current flows. So you can leave the battery connected without any problems.

Last but not least, you can press and hold the power button for about 10 seconds to turn Synkino off. By the way, the Synkino is really switched off, not on standby. So there is no reason to disconnect it from the power supply.

Version History

Version 1.1

  • Significantly improved speed readjustment with much less oscillation
  • Increased control range (17% to 116% of original speed in CD quality)
  • Support for other sampling rates for up to 227% accelerated playback (“scratch mode”)
  • Significantly reduced crackling and popping noises when switching on and off
  • Changes to the projector configuration are now effective immediately without a reboot
  • The operation works with 1, 2, 3 or even 4 pulses per turn
  • Synkino is serially accessible, expandable and programmable via the Arduino IDE (board type: “Optiboot on 32 pin CPUs”)
  • Improved reliability of film leader detection
  • No more immediate shutdown after the end of a playback

Version 1.0

  • Initial version, unfortunately plagued by a cascade of vicious bugs and therefore virtually impossible to use. The update to the latest version will of course be carried out free of charge by me.