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For sale: Crystal Sync Controllers for Konvas and CP16R

aapo lettinen

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I have couple of ongoing crystal sync controller projects which I originally intended for my own use but it would be great to be able to sell couple of finished systems to other forum members to cover the developing costs and to help others to shoot their movies better 🙂

The current models include a crystal sync modification to the Konvas 15EPSS motor which converts the motor to 24 - 30v battery and replaces the original electrically stabilized control box with my new Crystal Sync Controller. My controller design enables 16 internal Crystal Sync speeds and a Variable non-crystal speed function.

I have finished one of these controllers so far (sold to the customer in the US) and two more are on the way waiting to be assembled. The current v1.2 firmware allows storing counter information to the onboard memory to save counter information when power is lost and it has couple of additional features compared to the 1.0 version, like the possibility to record pre-set take lengths to save film on certain types of shoots. The controller allows shooting up to 64fps in crystal sync with the modified Konvas 15epss motor. The framerate presets are somewhat customizable and may differ between controllers, please ask for more if wanting special framerates or other custom options 🙂

Price for the controller including the modification of customer's 15epss motor is 800USD+shipping. 

The images and video are of the 1.0 version, the Konvas controllers for sale are from firmware 1.2 onwards:



Please let me know if you are interested in these Konvas controllers. Ordering one requires shipping your existing 15epss motor to me for modification (installing the internal speed sensor to it and modifiying the motor to 24v use) . The work takes from 1 to 2 weeks if I have the controller box already ready for shipping. If needing to assemble a new control box it typically takes an additional 2 weeks.

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This is the first mockup version of the controller I am making for the CP16R camera. It is a external 12-speed crystal sync controller which is connected to the camera via a special cable and enables using the CP16R cameras which have broken original electronics. Only the original camera motor itself is needed, the rest of the electronics are replaced by my modification.

- framerate presets as seen in the picture

- no shutter parking but one can use the 3fps inching speed to reach correct mirror position

- external start-stop switch with cable included

- possibility to extract start-stop signal from the controller to control external devices

- possibility to extract the crystal speed signal from the controller to control external devices

- film end warning most likely included. I am just testing this feature at the moment how well it integrates with the system


I am planning on making a single batch of these in February to gain more funds for making more advanced modifications for the CP16R later on. So it is a great opportunity to get your non-working CP16R back to life for reasonable price and to support the further modifications at the same time.

This modification is relatively cheap, 500 USD + shipping.  It requires shipping the whole camera body to me for the modification and one gets the camera back in couple of weeks with the Crystal Controller installed. As said I am planning on making only a single batch of these in February and it is probably not going to be available after that.

Please note that this is a quickly made mockup version and the final controller will have professionally printed markings. The framerate presets are the final ones and I have the circuit boards and software already finished, only the external case and control panel need more work: 


Please let me know ASAP if you are interested in this CP16R controller. It is only available for a limited time and I will need to assemble all the units at the same time in February so will need to know beforehand how many cameras there would be to modify then.

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On 1/14/2022 at 12:23 PM, aapo lettinen said:

Photos of the Konvas 15epss controller v1.0 :




Design locked for the one control box I am finishing this month and which will be available for purchase in February.

it will have the same framerate presets than the v1.0 seen in the photos and videos I posted but in the place of the 40.00fps preset there will be a 33.333fps preset. The Quick Select speeds will be the same (varispeed, 22.01fps, 24.00fps, 30.00fps, 48.00fps) and the firmware updated to the v1.2 version which has the possibility to save counters to the internal memory so that they are automatically called on startup and which has the possibility to set predetermine take lengths after which the camera will automatically stop (for example for shooting exactly 16ft or 20ft takes all the time if needed to save film in situations where one needs approximately fixed length shots) .

Let me know if wanting to order this version, I'll have one available in February.

Additionally I have one extra Konvas motor and camera if anyone is interested purchasing a modified motor or a motor with a 1M camera body and mags. The motor and camera have the less common 4-teeth rubber connector on the motor axle.  If selling the motor or motor+camera I would be able to purchase another camera+motor kit from ebay and modify it later in Spring to sell it too fully modified and ready to use (just add lenses). just a thought if anyone is interested in this possibility 🙂

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The current design of the CP16R external box controller has a film end warning system which gives an audible warning when the preset film amount runs out. The film amount is selected using a 12-position rotary switch (just a coincidence because they are the only switches I have available at the moment).

This gives the possibility to select the film amount in 10 meter intervals so that it is easy to use short ends with the system.

Turning the film amount selector to "0" position resets the counter so that one can change the magazine and choose a different film amount for it.

I will add a 9-pin accessory connector to the control box so that it is possible to output the following signals from it to external devices to add lots of extra functions if needed:

- crystal reference frequency (shows the exact framerate preset the system is set on at the moment)

- serial output 9600 baud if I get it working correctly (the serial data contains film counter information and can be used for extrenal footage counters, reading it using a computer, etc.)

- motor encoder signal (speed sensor signal) output (shows the exact framerate the motor is currently running )

- open collector output to control audio recorder start-stop etc. devices when the camera is started. Comparable to a switch which closes momentarily when the camera motor is started or stopped

- start-stop switch connection to add more start-stop switches if needed (one can control the start-stop with electrical devices like Arduino too if taking the time to figure it out)

- unregulated power output for external devices which consume very little power and which have their own voltage regulator. Couple of hundred mA can be taken out from the connector. (It is easy to cause damage to the system if making a wrong connection to this pin so extreme care is needed when using this)

The accessory port signals are extremely useful for persons who want to develop their own accessories for the system or if wanting to add a display or other accessories later (I can develop accessories too if needed). There is a catch though: it is relatively easy to cause a short circuit and destroy something if making a wrong connection to the accessory port so extreme care is required when tinkering with this extra connector and I recommend using correct metering and oscilloscope to double check the connections before using them 🙂


I WILL WAIT TO GET AT LEAST 4 OF THESE CP16R CONTROLLERS SOLD BEFORE MAKING ANY FURTHER SYSTEMS FOR THE CP16R.   The external box system is available for order now and I will post material of the prototype when getting it fully finished.

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