Changing a Elmo ST1200 to an ESS controlled machine like the GS.

[Thomas Knappstein]

Hello to all!
Inspired by the Topic of Phils Motor control Board which is amazing ( Phil you did a great Job), I found a few old Pic´s from 2014 when I try to make a Copy of this Motor control Board too. In this Days I had only one GS 1200 and this machines are very expensive. So I decided to make a ST1200 to be controlled by a seperate ESS controll Box even like the GS 1200 has it inside. I study the electronic Diagram of the GS 1200 and began to rebuild the complete Motor control Section on a seperate Plate. It took two Month to get all this Japanese Transistors. Most of them where out of Stock today. After testing the new control Board I assembled all into a seperate Box and put in a new Main Motor into the ST 1200. The old one is only used for Lamp cooling now. The Speaker I have changed to a little one. The Two Blade Shutter has only 40 Degrees dark Areas for maximum Light output with the 15V150W Lamp. A seperate Gear Motor for the take up Arm was installed, controlled by the same Board like the GS 1200 has for his rewind and take Up Motors. At last this Machine becomes two long Arms for big long Play Reels with a Capacy of 2 Hours Super 8 Polyester Film playing on 25Frames/s.

I can´t rebuild this for anyone else, because it is a very hard Job. The reason why i post this here is to show what is possible with this wonderful ELMO Projektors. I´m not an electronic Ing. and have nothing to do with this in my Job.

[Graham Ritchie]

Fantastic Thomas

[Phil Murat]

Hi Thomas,
Fantastic "Conversion" job you did on a ST1200 machine. The "Governor" Board is a module included in the "ESS" function . Aim of "ESS" function is to drive the machine on a almost perfect speed as 25fps for exemple and perfectly synchronized on a source. To do that ,projector pulse signal comes from a sensor installed on GS1200 cam shaft (This eliminates fluctuations due to belt slippage).
That needs to replace main motor for a DC motor associated to a tacho generator or a codding disk with I/R sensor.

Very big job achieved here, involves a lot of manhours !!!

[Martin Davey]

I'm in ore of people like Thomas, who have the skill and knowlege to tackle and produce a successfully working project such as this!

[Janice Glesser]

Very impressive Thomas! This is ingenious. I commend you for your creativity and patience in successfully completing such a monumental project. Thank you so much for sharing with us.

[John Burgess]

I can do some simple electronics etc , but you have taken things to a new level. Exceptional work , you deserve a medal for ingenuity .
John

[Jon Byler]

Very nice! I'm surprised you couldn't find functional equivalents of those transistors from normal electronics supply houses.

[Nantawat Kittiwarakul]

Just came up a weird idea out of nowhere.

Is it possible to replace the original motor & all of its associated electronics with stepper motor instead? In theory this should be totally possible. But in practice most steppers I've seen would seems to be intended for low speed - high precision angular accuracy application, not relatively high-speed application like this.

In other words, is there any stepper designed to run at, for example, 1440 rpm continuously?

[Thomas Knappstein]

I don´t know if there is any Stepper Motor who can handle this. In 35mm are machines on the market with special Stepper Motors to do this.