Aapo Lettinen

Today I made a very basic magnetic encoder disc for the first tests I am going to run soon. I had these axle fittings from another project so was fastest this way... I just put some neodymium magnets inside the bolt holes and sealed them with tape after that. This adapter is made for slightly larger axle but the fitting works OK for the first tests after I added some tape on the motor axle ? I am going to design a better encoder system later but this is great for tests and demonstration purposes. I am going to use self made Hall sensor circuit for reading the magnetic field changes which are used for generating the speed measurement signal after treated in the self made preamplifier. Everything extra is stripped from the camera body so that I can get good access to the motor. Easier to work that way. I am probably going to keep the original battery voltage meter so it can stay for now ?

real Crystal Sync of course with all speed presets being Crystal and very accurate

if there is the circuit schematics of the control system available we can try to guess what could be wrong with the camera. I have understood that the system is "electrically stabilized" speed control. I am assuming it's reference voltage based. In that case it could maybe just be a mechanical fault in the speed selector or its connections. Just guessing, impossible to know without the circuit schematics. (the way I would do that type of speed selector would be with the selector choosing different reference voltages from resistor bridge which is set up between full voltage and ground. The "stuck" selector would indicate that the resistor bridge does not work correctly so the voltage is stuck to either end of the resistor bridge. For example faulty ground connection on the bridge would do that. This is, again, guessing because I am not sure how they have done the selector, I am basing this guess on how I personally would do that type of design the easiest way) .Opening the camera to show the electronics could reveal some information as well and would give better understanding how the speed stabilizing works on that model. If my guess about the resistor bridge fault is right there could be a mechanical fault which could maybe be even seen and repaired easily.

I am more confident making new speed control systems than trying to repair old ones, not being familiar with that particular motor type. Is there still technicians working on these motor models able to repair the old electronics? if there is any, that would be the first option to try. if you want, I could probably be able to make completely new control electronics to the motor if needed but it would be pretty time consuming and possibly expensive. If you want additional features like additional speeds and a display and so on then it could be useful

for microphone, a cardioid mic is better than omnidirectional in this application. You will not want the mic to pick up too much sound from the back (the direction of the sound source) because that sound arrives to the mic earlier than the sound the parabolic reflects you really want to record. All the sound waves which are picked up should be in same phase. Thus you need to know the focal point where the mic is placed and then you should select the microphone's pickup pattern so that it covers as much disc area as possible but nothing extra from the sides and nothing at all from the back. So that the mic "sees" only the disc surface and nothing more. This gives you the best amplification and the best S/N ratio

I researched these briefly some years ago and even purchased a small-ish eBay one for testing. They are not as easy to make as one would think if you want to get good quality audio out of them. I don't have the links anymore which I used for research but one of the things is that you can really tune these things to work well at only one pretty narrow frequency range at a time. The other frequencies are not amplified as much and they don't have the same directionality characteristics so you will amplify very narrow frequency range directional spot from the front and then all the other sounds and noise will surround it from all over the place. For most applications the end results sounds pretty weird. For example it is not good to try to record dialogue with these things because they miss the low frequencies of the human speech and over-amplify the mids. Better low frequency response means that you need larger parabolic disc. at some point it becomes impractical to use and challenging to make. And too heavy or otherwise awkward to use efficiently. Picks up wind, wobbles and is challenging to transport. Thus the existing solutions tend to be heavy compromises between practicality and usability, usable frequency response and directionality and cost. And you'll still need the mic which you would probably not want to manufacture by yourself (it is possible but not practical) It needs to be real parabolic (spherical does not work, it does not have defined enough focal point and it causes phase differences to the sound waves which reflect from different parts of the disc) and it is pretty precisely tuned construction even if it looks simple and easy to make. The mic placement and mic pickup pattern needs to be precisely set too according to the disc cracacteristics. I think the eBay disc I purchased was pretty OK working for the price but the mic placement had to be set by about 5mm accuracy to get the best sound out of it. And it only worked well at very narrow frequency range... I metered it back then but can't remember right now. I think it was something like about 600 to 1300 Hz frequency range where the system worked OK and the rest of the frequencies were not amplified and sounded weird. I know couple of nature cinematographers who use Telinga parabolic mics. I have understood that they are pretty good for that kind of stuff https://www.telinga.com

I'll test how that would work! I am probably testing some type rechargeable Li-Ion batteries as well. The main goal is to have a small battery so that it does not take much space and leaves more room for the control boards.

I started to modify my new Leicina S to real Crystal Sync as soon as it arrived today. There seems to be a demand for sync sound Dual 8 cameras so the update, when ready, will become available for order one way or another. I will do a lot of prototyping and testing in the following months and will post the results here ? The first stage was to disassemble the motor side of the camera to see what the possibilities are to attach a speed sensor to the original motor and how much there will be space available for the circuit boards. I also calculated the reference frequencies needed and did some drafting. The next stage will be to manufacture a custom speed sensor assembly for the motor and then hook it up to my existing Crystal motor controller prototype and start to run sync tests. I can already say at this stage that this WILL work correctly. Release schedule is TBA at the moment but I would say "pretty soon" at this stage because I already know how to do this conversion and have most of the electronics design ready ?

very old thread but I just wanted to add my 2 cents because this thread pops up in google searches very often when trying to find information about crystal sync motors. For "Crystal Sync Motor" I mean a brushed DC camera motor which RPM is phase locked to a stable crystal oscillator signal so that the motor speed follows the oscillator reference as closely as possible. The motor speed is adjusted with closed loop controller so that it stays as close the Crystal reference as possible no matter how much the motor load changes. DIY crystal sync is fully possible. "Possible" does not mean easy but it can be done. I started a camera motor project this January which quickly turned to full crystal sync with multiple speeds and display and everything. At the moment the system works correctly and I am designing the circuit boards having the schematics ready and components chosen. First I thought I wanted to just make a simple servo controller with simplicity in mind and no need for high accuracy speed stability. Just using an Arduino for simple speed measurement and just using the low speed arduino pwm for controlling the motor. No displays or anything. But eventually it turned out I really wanted to have a real crystal sync system which phase locks to a crystal oscillator reference signal to be truly accurate. And the display seemed to be really useful so I wanted that too. Multiple speeds were a must as well. By my opinion, you can start simple and try to make the simplest system you can. Then it may even work correctly. But the simplest shoestring system is never enough as a final solution and eventually you will want (or need) more features. Then you need to redesign the whole system. After some time you need to redesign it again completely. Either you add all the needed features from the start OR you will end up in a constant loop of updating and redesigning. It is a nightmare for people who just want to shoot with the cameras, NOT build them. And designing a really useful and possibly complicated system from ground up takes lots of time and testing and even money. You will lose your nerves countless times and without enough motivation you will abandon the project and move up to something more interesting. Not trying to be discouraging, it's just the way it is. I tested the 4046 chips too. They were working pretty OK but I had serious problems getting the locking range good enough so it was simpler to just write a microcontroller code which does similar style of phase locking task but has practically infinite locking range. It took lots of time of course but it is just a more advanced way to do these things. So the actual phase locking function seemed to be easiest to do by programming a microcontroller. Then you need of course the speed sensor which reads the motor speed. And a preamplifier which conditions the sensor signal so that it can be used for the phase lock. Sensors can be optical, inductive or Hall sensors. Or sensorless though it is tough to do. Inductive sensors ("AC generators") can be the original Pilot Tone generators some camera motors have built in. For optical one can use a slotted or reflective encoder disc with some kind of LED light source and some kind of photo sensor (light diode/transistor) or a "fork-style" assembly which has both the LED and the light sensor in the same package. For Hall sensor one needs magnets attached somewhere to the motor axle so that the changing magnetic field can be measured by the Hall sensor and used as a speed measurement signal after conditioning. Sensorless speed measurement uses the current spikes which the carbon brushes make when they are switching from rotor winding to another. Sensorless measurement needs lots of additional components and signal conditioning so for most systems it is probably much easier to use the other sensor styles. You need a crystal reference oscillator of some kind to generate a very accurate speed reference signal which the phase lock can compare to the motor's speed sensor signal. So some kind of Crystal oscillator section is needed. One can use traditional frequency dividers/counters like binary or bcd dividers to get the multi-megaHz crystal oscillator signal down to suitable frequency to be used as a reference. For example something like the CD4020 binary divider can be used for testing purposes and some of my first prototypes used partially that circuit. This task can be done by programmable dividers too. Or one can use microcontroller as a custom frequency divider ( ctc interrupts) . On my designs I am using all of these depending on which one is the most practical for that particular system. Depending on the system you may need to use multiple techniques so it is best to be familiar with them all. At first I used low speed PWM directly from the Arduino programmed microcontrollers. After some time I learned how to do analog PWM controllers and updated to 38kHz PWM which one of the current designs uses. Digital high speed pwm is also possible but the analog system was pretty interesting to do so I wanted to try it and got it working pretty well. Some other systems will use digital depending on which style is the most practical in that application. You will NOT want to use low speed PWM signal in these systems. It works for control purposes but the noise is a nightmare and you will want to update it to high speed as quickly as you can. Use something which is higher than the human hearing range. For example the 38kHz my current prototype uses works just fine. You will really want to use mosfets when driving the motor. Bipolar transistors are not very good for that application (heating, power loss, possibly a bit more complicated to control with low power circuits, typically physically larger sized for same wattage) and mosfet is even a bit simpler solution in the end. It needs a higher level control signal to saturate fully (it is switched fully on/off quickly by the PWM signal and you will want to avoid the intermediate states so that the internal resistance of the mosfet stays as low as possible to avoid power loss and uncontrolled heating). So you may need to amplify the pwm signal before you can feed it to the mosfet's gate depending on your design and operating voltages. A bipolar transistor will do for this amplification stage or other means will work as well as long as the gate signal is high enough level compared to the motor's actual supply voltage. By my opinion, these Crystal Sync projects are really not suitable for persons who want to only shoot with movie cameras. If wanting to make these, one must be very interested in electronics designing too as well as building cameras from ground up and making mechanical parts and endless number of versions and prototypes which takes many months. Most people are not interested in what is inside the camera or a car engine as long as it works... but for this type of stuff you really really need to be interested in everything technical and mechanical and electronic aspects of the filmmaking products. Another thing is that it is definitely much faster and easier and much much cheaper to just order a crystal sync system from someone else than to build something by yourself from scratch including doing all the research and testing by yourself and learning to program this type of stuff and so on. All in all, I would say: Fully possible to do DIY real Crystal Sync if you are really motivated and have from about 6 months to one year worth of spare time. You need to be really interested in programming and electronics and mechanical stuff. Just wanting to shoot with film cameras is not enough motivation and the project will definitely fail. Use high frequency PWM from the start, you will need it anyway and it may be difficult to update later without redesigning the whole system. The phase lock will probably be a bit easier to make by programming than with logic circuits. Mosfets are the way to go for motor control circuit. For speed reference you can use various techniques as long as they are all based on real Crystals (no external or internal resonators, no 555 style lower accuracy circuits). Check with your oscilloscope to verify the function and accuracy of your reference signal. Oscilloscopes are a must when making these systems. You can't get you system working well without having a good oscilloscope (or two. or three. At least you need one which has two channels or more.) and know how to use it properly. Every signal stage needs to be checked and adjusted with the prototype using the oscilloscope measurements. Without the oscilloscope you can't even know if the system is working correctly or not. If someone is interested in my DIY crystal sync systems, I am making videos of them every now and then. I am updating them here and you can find information in other forum threads as well. https://www.youtube.com/playlist?list=PLXvIUtmF3OxvOYgAHWEapJQzL9e_DCWvX

The developing is a real problem if you want to diy develop long rolls. There is practically no DIY tanks at all for longer than 100ft so you need to either bucket develop or send the longer rolls to the lab. Fomapan can be ordered in 50m rolls and factory replied that longer rolls are possible too if you order at least 10 at a time

My diy scanning system is not very good and I am updating it at the moment. Most of the flicker is caused by that. Sometimes there was some inconsistency with the developing as well. The older rolls are diy developed in the upb1a tank which only handles 15m of 35mm at a time. Later I purchased a Russian copy of the Morse tank which can handle full 100ft loads

The stills stock has ks perfs and different pitch so won't work on pin registered cameras without modifying the camera a lot. Don't know about how it would work in arri2c but I shoot these stocks regularly with my Konvas cameras and they work pretty well with them. So if your camera does not have reg pins and have large enough tolerances the stills stocks should work. A stills lab would probably not be able to develop the whole 100ft roll but almost all motion picture labs can. You can also develop the 100ft at home if you have suitable tank for it. I have some stills bulk film examples shot on Konvas, check my channel (A Lettinen) on youtube

Yes, that one I forgot. Make sure to run down the spring motor before removing the plate

It is possible to remove the main plate on these cameras without messing else than the sprocket wheel position. If you cant get a refund you should take the plate off to see what is wrong with the spindle. Make sure to mark the sprocket wheel axle alignment before removing it. Remove pressure plate. Then take the outer edge screws off and lift the main plate back edge first by lifting from the feed or takeup spindle. Send us pictures of the insides if you decide to remove the plate for inspection

I am actually mixing my own developers. The bleach solution being the same one-shot style I am mixing from Potassium Permanganate and Sulphuric Acid. I like to cheap on things so I am diluting the acid from 96% to the working strength (Much cheaper that way) so I'm used to work with nasty chemicals ? The problem with the first test batch was that either the Bleach stage was too long OR the Clear solution was way too strong. It seemed fine initially but at the final developing stage the emulsion came completely off as a black goo leaving just clear film base behind. I followed the Ilford reversal process but already halved the Bleach and Clear strengths. Is someone familiar with that process, or more accurately does someone know what is wrong with the Ilford recipe and how to fix it to work properly? At the moment I suspect the problem was that there is the wrong concentration of the metabisulphite stated: "Add 25g sodium or potassium metabisulphite to 800ml water. " Maybe it should be 2.5 grams per 800ml? maybe they just forgot the decimal mark from the recipe? Because the current solution is so strong that it removes the manganese dioxide stains in, like, two seconds ?

Still waiting for my eBay purchase (Leicina S) to arrive so that I can start working on the Crystal Sync conversion. But it seems very likely that this update will work and will be available pretty soon. Probably later this year. Our local film supplier started selling color Dual8 (2x8mm) films too so this format is definitely gaining lots of attention fast. https://mutascan.film/en/product-category/films-8mm/ I purchased a old beaten up Camex Reflex for cheap and it arrived today. Such a beautiful piece of kit. Shooting first tests on Fomapan R100 now and figuring out the correct bleach + clear times for diy developing. I have a Lomo Lantan 2x8mm too but will definitely like the Camex Reflex more. Can't wait for the Leicina to arrive :)

it would be easy to install that type of switch as long as the switch can stand the current requirements. It will make charging the belt a little more complicated though if you discharge it at 8v but then want to charge at 12v so that some of the cells are full when the others are near empty. I would maybe use a separate 8v charger in that situation and only charge the drained cells (keeping the switch at 8v position when charging)

I think most of my batteries are this type and pretty well working though they self discharge pretty fast (maybe something like 1 - 2 months or so). Not from this seller but the battery looks similar. https://www.ebay.com/itm/8-4V-NiMH-3800mAh-Rechargeable-Battery-Pack-Tamiya-Plug-for-RC-Toys-Charger/352689401762?hash=item521ded2fa2:g:dXAAAOSweSdc~62d That charger works but it is very slow charging so it is best to get your charger from the local RC or Airsoft store and get one which has selectable charging current (mine has adjustable current from 0 to 5 A) . I use this charger with my batteries: The local store probably has high quality batteries available as well though they will be much more expensive than the Chinese ones. One thing to look at with these is the stated capacity: the higher the number the lower quality the battery may be if the outer dimensions of it are the same. Those 3800mAh ones are by my opinion pretty OK but will self discharge faster than the lower capacity ones. If this style of battery is listed as 5000mAh it is probably pretty low quality though could probably still be used if your charger is powerful enough. Check the local store and if they have 8.4v batteries which are something around 2000 - 2500 mAh they should be fine. You can ask for high quality batteries if they can recommend some

the easiest way to power 8v camera motors is to use Airsoft / RC Car nimh batteries which have tamiya connector. These can be got in 7.2V and 8.4V and it is very easy to make a adapter cable which connects to your camera. You can get additional chargers easily and as many batteries as you want and they are affordable. (if getting extra batteries, make sure to regularly keep them charged to avoid them going bad. High capacity low quality batteries tend to self discharge quicker than good quality low capacity ones.) I would keep the battery belt just the way it is and just get couple of the 8.4v airsoft batteries and a charger. you can make your own belt clip for the batteries. I like to use velcro for mounting them to the side of the camera

I believe it could be possible to get a Konvas 1M package with a crystal motor for that about 1000usd budget. Basically you would need to purchase a Konvas 1m from eBay with two or three mags and send it to Olex for full CLA. I should have a fully working original konvas crystal motor for sale soon with two different 4-pin xlr adapter cables, spare fuses, two nimh batteries and a cheap-o battery charger. Depends on how my own crystal motor projects will progress. the motor + batteries and other stuff : 500usd camera body and mags : maybe around 200usd or so cla by Olex: ??usd shipping and customs costs: ?? usd Lenses will cost extra of course. But the oct18 lenses are much cheaper than oct19 ones so you will save by choosing the Konvas 1M model instead of the 2M. ---------- If you are not interested in crystal sync or orientable viewfinder , you could use the older rheostat motored 1KCP konvas camera with side latch mags and straight viewfinder. That can be pretty cheap if you do the CLA by yourself. Probably you could get the camera body, motor and mags for about 300usd including shipping and then the rest could be used for lenses. I use this older rheostat model with 7.2v airsoft batteries for most of my MOS stuff: I am developing a crystal motor for this Konvas model later this year but it will be costly, the modification price being around 600usd or so. The 1M would be a better option if you need crystal sync but just good to know that it is possible to get the older model run on crystal sync too if you need it sometime later

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. 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.

Nice work! Keep us updated about the progress :) I have been working on my own Crystal Sync system for a while and managed to get it working pretty well. One of the challenges was that the approach I used necessitated pretty high sampling rate (thus high loop running speed on the program) so it was not possible to add any display functions or other extra without compromising accuracy. I resolved this by using a separate microcontroller for the motor control and all the user interface functions are handled by other microcontroller which is allowed to run at slower loop speed. So with my approach and phase locking algorithms it was not possible to make a well working system with only one microcontroller if a display is necessary. But I would be very interested seeing your take on the Arduino crystal sync challenge and how you are resolving these issues. Are you planning on adding a display and multiple speeds?

do you have a MFT mount stills camera or similar camera which can be used with C-mount adapters? it should be pretty easy to test the lens with such a camera to see what it exactly the problem. I personally use GH4 with C-mount to MFT adapter for this type of tests. easy to see the lens characteristics by using the 1x or 2x magnify on the screen

front anamorphic lens is basically a spherical lens with a wide angle attachment which only works to one direction rear anamorphic lens is basically a spherical lens with a rear extender which only works to one direction a spherical rear extender basically takes the center part of the image and magnifies it. In the process one loses some light and also magnifies any aberrations there is. Additionally the extender may not physically fit to the back of the lens. But generally there is no optical reason why it would not work unless the image quality ends up being so bad that one does not want to use the system (imperfections of the original lens magnified too much to be tolerable) or the light loss being too much (the typical one or two stop loss of the extender combined with the possible stop-down requirements of anamorphic lenses to get good enough image quality for cine use. So with anamorphic one would end up to somewhere around T8 maximum aperture with a 2x extender?? )

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. 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.