What is the origin of the term "DOM Motor" for a single stepping motor?

[Duncan Brown]

I thought I'd seen this term more widely, but right now I can only find references in Arri stuff.  DOM Motor seems to mean a motor that will single step, I think with one press stepping the motor to the point of opening the shutter, and then next press spinning it to the shutter closed position.  I can't come up with any words that fit D-O-M.  I just know it's going to be something stupid, like with "MOS Camera"...

Duncan

[Charlie Peich]

Greetings Duncan! 

"I just know it's going to be something stupid, like with "MOS Camera"...

Close.... 'DOM' is the 1st 3 letters for......... are you ready for this? .... 'DOMestic'

Noun: something produced or manufactured in one's own county.

Arri USA used 'DOM' exclusively to identify any Arri camera equipment that was 
designed and manufactured in the USA, not at the main factory in Germany.

This was when Arri Germany and Arri USA were separate organisations. 

The most popular item was the DOM Animation/Time Lapse motor
for the 16S and 16M cameras.

Way back in the mid '50s, there was an interest in 'single framing' with these 16mm cameras.
The cameras were not really designed for single frame operation, but Arri offered this 'lightweight' motor in April 1956...
 

 

Meanwhile, back in Germany Arri factory made 'The Single Frame Gear'. This unit fit in between the camera and the drive motor.
Not very popular in the U.S., in my opinion.
 

 

So , Arri USA continued making and refining the DOM unit and ended with this version in the late '60s, early '70s.

You still had to get a capping shutter which came from Germany.
 

 

Hope that answers your question...

Charlie

[Duncan Brown]

Haha yep that's pretty DUM ?

Do you have the full instructions that presumably exist behind that last image you posted (the one with "Operating Instructions" at the top)?  I have various pieces of that rig.  An intervalometer manual would be cool too, if anyone has one.  Though it's all pretty simplistic, just a matter of tracing out the wires inside if I have to.

There's a dizzying array of connectors involved in all this stuff.  Even things that look like they belong together are connectorized differently.  The intervalometer has what look like male DIN connectors on the front panel, but with no provision for the shell that is usually around the outside of a cable-mounted female DIN connector.  Looks like I will have to try de-outer-shelling some female DIN connectors and see if they fit.

(Edited to add: I recently came up with one of those "Single frame gear" units too.)

Duncan

Edited April 28, 2022 by Duncan Brown