ALCS konvas 15epss stabilized speed controller

[Aapo Lettinen]

I am making a electronically stabilized (not crystal sync but should still be pretty good accuracy) speed controller for 15epss motors.

It is basically a replacement for the original speed control box of these motors as it is getting hard to find the original boxes nowadays. I am making a as-simple-as-possible device with couple of speed presets and which works at 24 volts. No displays or anything fancy. The device is way smaller than the original konvas controller, I am intending using the same casing than my Eclair 16-speed and 12-speed controllers use so very compact.

Price 450usd and should be finished in the next following months.

It is needed to replace the motor connector with new different one and to internally connect the wires inside the motor handle differently so that the motor works at 24 volts instead of original 48 volts. This modification is simple enough to be user made but I can arrange it here too if needed.

Let me know if wanting to order a controller like this. I have possibility to make crystal sync modification for 15epss too but they cost about a grand and most users don't need the features so wanting to see if this simple more affordable device would have use for them 🙂 

[Aapo Lettinen]

Finished designing the circuit board and sent it to manufacturing now. Will get them back in February so late February/early March is the most probable finishing date for the project.

Let me know if wanting to order one. If wanting to save costs it is possible to install the new connector to the motor cable and modify the motor to 24 volts by yourself so that I would just sent the new speed controller and the necessary connectors and instructions to make the modification.

 

btw the same board will probably work with Kinor16 original motors too if wanting something simple and affordable to replace the original often unreliable control electronics and not needing crystal sync. I can test this sometime later 🙂

 

Edited January 19 by Aapo Lettinen

[Aapo Lettinen]

two of these 15epss controllers ordered so far. There is capacity to make much more of them so let me know asap if wanting to order one, I will preferably assemble them all at the same time 🙂

[Aapo Lettinen]

Finished front panel will look like this.

there is one controller available for order from the April2025 batch, let me know asap if wanting to order it. Will ship in late April / early May. 

Will try to make more of them in Summer but will see if it is possible. Recommending early ordering if needing these as I have tons of other projects and if missing a manufacturing batch it may take long before next ones are made, likely from 4 to 6 months or more

 

[Fred Ansaldo]

That's pretty cool. I have the original box but I think it might have a problem as the camera stops running after a minute or so, so I might go for one of these if I can't fix the OG 🙂

[Aapo Lettinen]

2 hours ago, Fred Ansaldo said:

That's pretty cool. I have the original box but I think it might have a problem as the camera stops running after a minute or so, so I might go for one of these if I can't fix the OG 🙂

I never had the original 15epss control box but it has 48v inverter circuit inside which generates heat. If the camera runs fine at first but then suddenly stops after quite long-ish take, it can be heating related issue I think. There may be some bad soldering joint or faulty component which expands when warming up and loses connection when warm enough.

could be more complex issue too. don't know the exact circuit of the original box so difficult to say but you can probably figure it out when opening it (remember that 48v is already dangerous and a faulty circuit can generate more voltage than originally rated for so definitely have all safety measures in place before attempting any repairs) . if it is heating related issue it may not show up the same way if the casing is opened for testing purposes, this can complicate repairs a lot

[Fred Ansaldo]

THanks ! 

What is the wait time for your controller these days ? 

[Aapo Lettinen]

22 minutes ago, Fred Ansaldo said:

THanks ! 

What is the wait time for your controller these days ? 

I am assembling couple of them in the following days and testing after that. I have one extra in this first batch which I could sell. I guess from 1 to 1.5 weeks with shipping for that one extra unit on the batch. depending on how long the tuning and testing of these takes (and if you modify the motor handle by yourself to work with the controller. you will need a multimeter and soldering iron and some basic tools like small screwdrivers for the modification and a cheapest multimeter which has continuity testing. One needs to change the wiring of the motor to work at 24 volts and then replace the original cable connector with new different type one. Should take maybe 30min to 45min total with testing. It would also be possible to send the motor handle here for modification if longer shipping time is not an issue)

Edited April 26 by Aapo Lettinen

[Aapo Lettinen]

Thermal stress testing. I am testing the heat generating parts with thermal camera at maximum load to ensure that they are not overheating in use.

Decided to mount the power FET differently but otherwise works fine. Small software tuning and remounting the FET with more passive cooling, then it is finished.

 

 

[Aapo Lettinen]

First finished device sent to a client today. Will assemble two more soon and make some tutorial videos of it.

The preliminary stability tests looked like it could be used for short sync sound takes easily if calibrated correctly. Temperature changes the calibration so one needs to let the device warm up properly before trying calibration. I think one could try shoot 1min to 2min sound takes with this device without much issues. The speed stability is really good, it is just about whether the selected speed preset is a little offset a little up or down if the calibration was done hastily at different temperature than the device is normally running at. 

The variable speed knob is sync too so it keeps the selected framerate constant during mechanical load changes on the camera. If hastily needing some speed preset which is not internally calibrated to the A/B/C presets, one could just use the variable speed knob to dial in some custom framerate quickly and check from the camera body 's tachometer if the speed is close enough to the desired one. It is not good for the internal wires to constantly open the device for changing the speed presets all the time, I estimated something like 3 times a year should still be fine so that the wires will last long. Of course you can do it more often if prepared to resolder some wires back to the circuit board if they snap after bazillion opening of the front panel 😄 

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There is one extra controller available for order, takes a week or two to prepare for shipping if ordered now. I don't know when I will have next chance to assemble more of these but probably late Autumn I think. If there is more orders I will make another batch when having possibility .

It is possible to diy modify the 15epss motor handle to work with this controller. Different handles have slightly different tachometer generators so the device is calibrated for the specific motor at a time and if using multiple motor handles with this you will need to recalibrate after changing the handle, or accept that the speed presets are a little off like 0.3 or 0.4fps off if the controller is not user calibrated with that particular handle

[Aapo Lettinen]

The remaining device from the first batch is reserved for couple of weeks, probably sold but need to wait. If someone has very urgent need ("must have this device!") to have this type of speed controller, I might sell my prototype device which has a scratch or two.

I can make another batch of these controllers somewhere between July and December 2025 depending on when there is enough orders in to make it possible. The manufacturer of the 6-pin connector managed to discontinue them just when I was ordering more of them so I need to change the connector type on the next batch, thus will probably need to change the front panel too to have different mounting for the other type of connector. this will create additional expenses. So I will need to collect two or three orders and can make more of these.

There is a deposit of 100usd when placing the order and when I have 2 or 3 orders or more I will charge the rest of the purchase price and make the batch.

Let me know by DM or on Instagram (aaplet14) if wanting to order these.

[Aapo Lettinen]

I will upload tutorial videos and other material of the device on this playlist:

https://www.youtube.com/playlist?list=PLXvIUtmF3Oxt6G5MuiBc-g4n1iZSAj9gA

[Aapo Lettinen]

On 5/20/2025 at 11:32 AM, Aapo Lettinen said:

The remaining device from the first batch is reserved for couple of weeks, probably sold but need to wait. If someone has very urgent need ("must have this device!") to have this type of speed controller, I might sell my prototype device which has a scratch or two.

I can make another batch of these controllers somewhere between July and December 2025 depending on when there is enough orders in to make it possible. The manufacturer of the 6-pin connector managed to discontinue them just when I was ordering more of them so I need to change the connector type on the next batch, thus will probably need to change the front panel too to have different mounting for the other type of connector. this will create additional expenses. So I will need to collect two or three orders and can make more of these.

There is a deposit of 100usd when placing the order and when I have 2 or 3 orders or more I will charge the rest of the purchase price and make the batch.

Let me know by DM or on Instagram (aaplet14) if wanting to order these.

I sold that remaining device now. Can make another batch later this year if someone needs these, let me know by dm or on ig if wanting to order and we'll figure out the schedule then