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Crystal sync motors for Russian cameras


aapo lettinen
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I have multiple crystal sync projects going on at the same time but I still should have time for one additional project this year :D 

I was thinking it could be usable to do a crystal sync motor modification for these old straight viewfinder Konvas models which use the older style rheostat motor.

 

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I could do the mod to my own camera first and then install it to other person's motors as well or just send the ready-to-install boards and parts so that the end user could install it by themselves. 

Would anyone be interested in this type of modification?  

These cameras are smaller than 1M and 2M models so they could find use in indie style shoots even when they don't have orientable finder like the 1M and 2M do. The camera bodies and motors are also more available than the 1M or 2M with a working  original crystal motor which are relatively rare. So I think the mod would be useful in today's world. 

Schedule for the project would be TBA (if the project even will happen). Prices and specifications would also be need to figure out but I would assume it would be nice to have 4 or 5 crystal speeds and the price of the modification could be something around 500 + shipping or something like that. It should be possible to install most of the electronics inside the spring drive cavity to keep the modified system as streamlined as possible.

Please let me know if you are interested :) 

I will finish the other projects in this Summer so after that it could be possible to concentrate on the Konvas motors if there is enough interest to make it viable :)

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  • 3 weeks later...


there was some interest in having custom speed crystal motor for the 1M and 2M cameras. So I will most likely check this option soon 🙂  if someone else is interested in 1M and 2M custom speed motors, you can let me know by PM. I will make some tests and prototypes in the next two months and should have some possible options available then.

At the moment I am using Kinor16CX-2M motor as a testing platform for my crystal sync camera controllers (I have two of these motors so it was the easiest one for my tests, just a coincidence) . So these Kinor motors will be easy to modify as well if needed (though Olex already has a very well working crystal motor for the Kinor16 so probably it is best to use Olex's motor with the Kinors unless one needs something really special like a one-off modification with lots of custom features)

I keep you updated when I have a working prototype to show 🙂 

 

Please note that this thread is specific to Soviet/Russian cinema cameras and making motor modifications for them. If there is more general questions or ideas about making stuff for other type of cameras, please start a new thread in the camera subsection specific to that camera model or a more generalised thread can be created in the "Camera Accessories and Tools" subsection of the forum.

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  • 3 weeks later...

It seems that the Konvas motor project may be delayed a little because there is not much interest for it. At the moment I am developing phase locking functions using the Kinor16cx-2m motor and my prototype crystal oscillator as a testing platform.

I am in the first stages of tuning the phase locking code so it does not work correctly yet but you can see here how I am testing these systems and what it looks like at this stage. I am using Attiny85 microcontrollers for these tests because they are fast to program with my tools and I have lots of them. I may migrate the code to other microcontrollers later when it is finished. Probably doing more videos also. There is info in the video description if someone is interested 🙂

https://www.youtube.com/watch?v=AGd8g07A4Kk

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I got the phase locking working  with my prototype. It still needs fine tuning and I will change the phase locking algorithm to get better accuracy and to get it working correctly under 16fps (160Hz). 

The prototype motor has 10-slot encoder so the frequency is 10 times the fps. So 16fps = 160Hz, 25fps = 250Hz and so on. 

Look at the lower frequency rating on the "Average", that is the median motor running rate. The upper frequency is the crystal reference frequency coming from the oscillator. 

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The whole motor control code is currently running from a single Attiny85 microcontroller. If wanting three digit accuracy I may need to use different system but as you can see this system is already pretty good. 

I will test this code version next with the motor attached to the actual Kinor16 camera and then I will get to adjust it with actual film load. The motor already reacts to changing dummy loads correctly so I am sure the current version will already work pretty OK with the camera but we'll see. I will probably post a video when starting to work with the full camera + motor setup :)

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Testing my refined phase lock + motor control code with the actual Kinor camera with dummy film inside. 

By quickly tuning the torque response I was able to get the average speed pretty close to the target. It is off by about .03 fps or so and I should be able to tune it to .01 fps accuracy with a little more work. 

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It is possible to get it close even with this simpler phase lock system but the accuracy varies depending on the frequency so I may need to make a response curve to compensate this. Even the current system would be usable for sync sound if one just compensates very long takes in edit by a frame or two if needed.

The advantage of this simpler system is that it can be made very very small. I am pretty sure I could fit this system to a matchbox or a little larger space if needed. But I will continue with the more accurate phase lock systems as well. 

Here is how I tested the system today with the camera. The cheap-o mini oscilloscope is for getting quick reference measurements of the motor speed and I am using the pc oscilloscope for monitoring the average speed and phase lock.

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  • 2 weeks later...

Tuning a crystal oscillator for a customer's project. The binary counter has built-in inverter-trigger section so it just needs the crystal, two resistors, a capacitor and a variable capacitor to get the crystal working with it. The circuit needs to be tuned with a oscilloscope to get the capacitance and bias right. 

I tested cheap Chinese crystals and a better IQD one. They could be used with the same bias but the capacitance requirements were different. The IQD one was more accurate though the cheap Chinese one was surprisingly good. There was signifiant differences in the sine waveforms (not shown in these images) so I will probably use the IQD ones in the final devices and the dirt cheap Chinese ones can be used for tests and prototypes. Good to know though that even the cheapest eBay crystals are pretty OK for most uses if you need to use them. 

The system needs another divider to get 240Hz and 480Hz. One can get 150Hz, 300Hz and 600Hz directly from this single divider.

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I have other means for generating reference frequencies as well. This type of crystal oscillator setup is just another tool in the box which can be used for the purposes where this type of system is the most beneficial choice. Frequency needs, available connections, size of the system, user interface etc.  matter a lot when choosing the best technique for frequency generation.

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  • 3 weeks later...

Drafting the user interface code for the first full system I am building. Now when the motor control and oscillator sections work well I am able to concentrate on the circuit board design and the user interface and display settings. 

The current system uses 16x2 lcd display. Here I am testing what kind of display modes could be useful for the end user. One can change these by push button. I have not tested the footage counter yet, it should work correctly but the accuracy needs to be tested.

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On the current hardware versions the footage counters will reset if the power is switched off. This is a practical decision to make the system much simpler and easier to use... the idea of the counters is that you can see how many feets the last take was and then write it down before changing the battery. External EEPROM would make the system much more complicated and it would need additional buttons to reset the counters so this is a much simpler approach. 

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On 3/31/2020 at 12:51 PM, aapo lettinen said:

I have multiple crystal sync projects going on at the same time but I still should have time for one additional project this year :D 

I was thinking it could be usable to do a crystal sync motor modification for these old straight viewfinder Konvas models which use the older style rheostat motor.

 

37429866390_d75a505a4d_k.jpg

I could do the mod to my own camera first and then install it to other person's motors as well or just send the ready-to-install boards and parts so that the end user could install it by themselves. 

Would anyone be interested in this type of modification?  

These cameras are smaller than 1M and 2M models so they could find use in indie style shoots even when they don't have orientable finder like the 1M and 2M do. The camera bodies and motors are also more available than the 1M or 2M with a working  original crystal motor which are relatively rare. So I think the mod would be useful in today's world. 

Schedule for the project would be TBA (if the project even will happen). Prices and specifications would also be need to figure out but I would assume it would be nice to have 4 or 5 crystal speeds and the price of the modification could be something around 500 + shipping or something like that. It should be possible to install most of the electronics inside the spring drive cavity to keep the modified system as streamlined as possible.

Please let me know if you are interested :) 

I will finish the other projects in this Summer so after that it could be possible to concentrate on the Konvas motors if there is enough interest to make it viable :)

I prepared one of my Rheostat motors for the modification today to check how much work it is. I will start to modify this in Autumn because I have some more urgent projects going on at the moment but it was good to check it early on to see how to modify it. 

I will definitely try to build the control electronics inside the spring drive cavity. Probably I will try to include some type of a small OLED display if it is possible. 5 or 6 crystal speeds. Price per modification would be 600 USD + shipping and possible Customs costs. The most efficient way to modify these would be that I would modify one of my own motors here and then the customer would trade their own working motor in, pay the conversion cost and I would send the already modified motor to them. Keeping the trade in motor to modify for the next customer. 

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The first stage of the modification process would be to make the motor run with a normal PWM controller. When that works correctly, then it is pretty easy to modify my existing Crystal Sync system to work with it. We'll see how long it takes to get it working perfectly.

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  • 4 weeks later...

designing the circuit board for the oscillator section of one of the motor projects (Crystal Sync update for one of the original Konvas motors. This update uses external box to house the control electronics). It is pretty slow work to design the actual circuit boards but the work  advances all the time.

I have updated the system menus a little making them more efficient and have also updated the PWM frequency of the motor control to 38kHz so that the motor does not create additional sound under load anymore. This high speed PWM is a major update and necessary for all the designs if one wants to do real sound work with them.

I will make a video of the menu system at some point. It is pretty fun to design the user interface. My favourite part of the project actually 🙂  

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  • 1 month later...

Coming soon:  my self designed and assembled Crystal Sync controller for the Konvas 15EPSS motor. I am assembling the circuit boards now 🙂 

It has a 16x2 display and lots of selectable speeds. All speeds are Crystal Sync and it is connected to the original handle motor of the Konvas 15EPSS via cable but it does not use any parts of the original Soviet control box. The original speed-regulated Konvas control boxes are rare in working condition so this update enables using all the cameras which have the motor itself but the original control box is broken or missing. 

I will post images when I have the boards installed inside the new control box and the switches are in place 🙂

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  • 2 weeks later...

I will test if I could modify the Kiev-16UE to work on Crystal Sync as well. We'll see how it goes. People have asked a usable but affordable electric crystal sync 16mm camera and I believe the Kiev could work for this because the lenses are affordable. We'll see how it goes in couple of months when I get the test cameras here to experiment with them. The goal is to make the final system with couple of Crystal Sync speeds for the maximum of 600 euros including the camera body and some lenses. We'll see if it is possible 🙂

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  • 4 weeks later...
On 8/26/2020 at 10:04 AM, aapo lettinen said:

I will test if I could modify the Kiev-16UE to work on Crystal Sync as well. We'll see how it goes. People have asked a usable but affordable electric crystal sync 16mm camera and I believe the Kiev could work for this because the lenses are affordable. We'll see how it goes in couple of months when I get the test cameras here to experiment with them. The goal is to make the final system with couple of Crystal Sync speeds for the maximum of 600 euros including the camera body and some lenses. We'll see if it is possible 🙂

I got the test camera today and checked how it could be modified. The Kiev16UE modification is possible as a motor-only modification so that one would remove the motor from the camera and send it to me, then I would modify it to crystal sync and send it back. No need to ship the camera back and forth. Price tag for the motor modification would probably be around 400 to 500 USD. 

No complete packages available, only the motor modification if anyone would need it. It is too much work for me to hunt down camera packages from ebay and service and modify them and that takes too much resources from the modification work 🙂 but if anyone is interested in the Kiev crystal modication, please let me know. I will build a prototype sometime later this year

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  • 3 months later...
On 9/17/2020 at 3:47 PM, aapo lettinen said:

I got the test camera today and checked how it could be modified. The Kiev16UE modification is possible as a motor-only modification so that one would remove the motor from the camera and send it to me, then I would modify it to crystal sync and send it back. No need to ship the camera back and forth. Price tag for the motor modification would probably be around 400 to 500 USD. 

No complete packages available, only the motor modification if anyone would need it. It is too much work for me to hunt down camera packages from ebay and service and modify them and that takes too much resources from the modification work 🙂 but if anyone is interested in the Kiev crystal modication, please let me know. I will build a prototype sometime later this year

I have done some experimenting with the Kiev and I think it might be useful if I'll test using a completely new add-on motor with it. Possibly a brushless motor if I'll find a suitable model (just testing some Chinese made ones which could work). The same motor could maybe be used with the Krasnogorsk cameras as well if modifying the output axle etc. connectors. Could be useful I think. I will continue the Kiev project with open schedule.

I am working on the Konvas 15EPSS motor system which should be finished in January. will post pics of it then :)    

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  • 4 months later...
  • 1 month later...

Finished the 24v battery for the system. It uses two 12v gel batteries in series and has a on/off switch and fuse holder. Long cable to allow keeping the battery on ground when operating. Pretty neat battery because the small shoulder bag is handy and excess cable can be stored easily inside the bag. Output is via 3-pin xlr ( 1 = gnd, 3= +24v ) . I will make a higher voltage battery for higher frame rates.

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I should complete the 15epss crystal sync controller in a week or so. Will post results then 🙂 

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