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ALCS "Universal" Crystal Sync 2-speed motor for 16mm cameras

Aapo Lettinen

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Hi you all!
I am finishing a simple 2-speed crystal motor in February which is meant to be more "multi-purpose" than my previous motors which were very camera specific. The goal was to create something relatively affordable which could work pretty OK with different type of cameras and has all the controls integrated to the motor so that the user just needs to figure out how to attach the 5mm output axle to the camera and how to mount the motor to the camera so that it stays in place.

It is basically a spin-off of my Eclair ACL motor unit but mirrored, with larger body and integrated 2-speed electronics and is meant to be mounted on the camera's right side. The current customer is going to mount it to a Krasnogorsk camera by making a custom axle modification and 3D printed connection parts for the camera, I am only supplying the crystal motor unit. Likely we will hear more about the Krasnogorsk project later on...

I will make couple of these basic 2-speed "universal" motors if anyone else wants to order one. I will post photos when having the final front panel and switches in place, should receive the circuit boards next week and the software is already finished.


Some specs:

- has one crystal speed and other crystal speed which is exactly double the first speed. So it has either 24fps and 48fps, OR 25fps and 50fps, OR some other speed and double that speed. I can change the speed settings here just before shipping but it is always one speed and exactly double that speed, NOT possible to select two entirely different speeds on the same device

- from 18v to 20v operating voltage. typically something like 19v is pretty fine for it. use a higher voltage battery and simple Chinese step-down converter to get the correct voltage for it if needed

- variable "wild" speed with potentiometer which adjusts the motor power directly

- adjustable top power limit for the variable speed, to roughly limit the top camera speed in variable mode

- locking "run" switch to run the motor continuously

- momentary "run" button which can be used to shoot short takes to save film, the motor runs as long as the button is held down

- power-in connector which has two wires for external run switch. the motor runs as long as the wires are connected together so one can install momentary or locking switches there

- for extra fee and waiting time it is possible to get a custom made dual motor axle with manual inching knob. the normal motor has a small screwdriver slot on the end of the motor axle which can be used for inching or you can try to inch with the variable speed using short pushes on the run switch

- rotation direction can be changed by removing/reattaching a jumper inside the controller. this should be possible to do using forceps via the ventilation slot but opening the panel is not difficult either and likely will only have to do this once if ever. if you already know the required direction I will change it for you before shipping

- the device is typically suitable for 16mm cameras where the motor is mounted on the camera right side and the camera runs relatively smoothly. Typically a 1:1 drive axle on the camera is needed (one motor revolution means one frame of film shot) but I can alter the framerate settings of the device to allow different gear ratio as long as the exact ratio is know. so for example belt drive could work if the ratio of the gears is known.

- the motor is 26w and typically not powerful enough to run 35mm cameras. might be possible with small like 100ft rolls but no guarantee it would work. No guarantee for it to work perfectly with every 16mm camera either but on most cameras it should be pretty well working

- it is not suitable for cameras where the motor is mounted on the back of the camera (arri16s , etc) because the end result would be extremely awkward and cumbersome. You are allowed to make crazy tests though if you want, it might still work for your application and would at least be entertaining ?

- not suitable for cameras where the motor is mounted on the left (operator) side, it would mean the controls being on the underside of the motor and all the text upside down which would make it a very surreal experience to try use it. so does not work with the Eclair ACL, I have different motors for that camera model.


Just send me a DM here or on FB or Insta. I will make couple of these motors depending on how much I have leftover parts from the ACL motor projects, there is limited supply but I will try to reserve as much parts as I can for these motors if possible.


the price outside EU is 700usd + shipping without custom motor axle (so having only the screwdriver slot for inching). 830 USD with the custom axle and manual inching knob for easy inching. Payment via PayPal.

For private EU customers I need to add 24% VAT but the motor can be paid with wire transfer in Euros to save costs and shipping costs are lower so the price works out to be on about the same level.


I will make a single batch of these to use the leftover parts from the ACL motor project. There is no other batch planned, I might make something different later for multi-purpose use but not guaranteed and will take a long time to finish. This device is available now so it is a rare chance to get a universal-style crystal motor for your camera modification project for relatively affordable price and good support ?

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Tested the software and circuit boards now and they work perfectly.

One update: the motor can be switched between 24/48fps and 25/50fps modes by the user by installing or removing a jumper inside. Just open the front panel by removing 4 screws, jumper on or off, front panel back on.

So no need to send it back to me for this kind of fps base change, I decided to add the jumper method so that it is easier for me to finish them and it adds security to the end user that they can make this change by themself if in some rare cases need to do it ?

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  • 4 weeks later...
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It is possible to order this 2-speed motor with a display update too!

the display allows choosing more base speeds, it has one button (not pictured, this is a prototype not finished yet) which is used to select the speed at startup.

The updated motor costs 1100usd + shipping and delivery time about 1 month. Two or three available depending on how many parts I have left in April.

The display adds the following base speeds:










So these are the selectable base speeds on the motor if it has the display update. The "1x2x" switch works similarly after the update so if the selected base fps is 20fps the motor speed is 20fps in "1x" position and 40fps in "2x" position of the switch. Similarly if the base is 30fps the "2x" position is 60fps and so on. So effectively the motor has a total of 18 crystal speeds after the update!

Normal motors with the internally switchable 24fps or 25fps are also available for 830usd + shipping just like before. They have delivery time of about 3 weeks at the moment.


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  • 3 weeks later...
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Posted (edited)

Here is some files where one can take mounting plate dimensions when designing how to mount this Universal Motor to their own camera project. Please inpect the photos carefully to see which holes are used for mounting, the motor is supposed to be mounted to the camera with four M4 screws/bolts and the rest of the holes are either blocked by the motor parts or already used for something else (mounting the motor drive or electronics box).

Motor axle is about 19mm lenght measured from the mounting plate surface. And it is 5mm axle. The screw heads of the brushless drive mounting screws are about 3.5mm height so leave about 4mm room for them and you should be fine.


Designing your mounting system should be easy, you can even print out the 1:1 pdf file of the plate and make a cardboard model of your mounting system if that is easiest way to work.I have one partially assembled 2-speed motor which can be finished in about a week or so after someone ordering it. So I have these available and can make more whenever needed, just need orders to keep them moving 🙂  two were sold last month so there is already people working on these

Edited by Aapo Lettinen
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