Advice for replacing a motor in a 16mm film projector

I'm attempting to replace the motor in a Bell & Howell 1592 16mm film projector. I'd like to have complete control over the motor, from slowing it down so that it plays at a speed as low as 1 frame/second to as high as 24 frames/second. To do so, I believe I could replace the motor with a stepper motor as well as control the electricity to the bulb (so that it doesn't burn the film when playing at lower speeds). What kind of motor do I need to get to replace the existing motor? (Or do I need to replace the existing motor at all?)

The specs on the label of the motor read:

0.7A, 3400 RPM, 1/20 HP, 7.5 MFD CONT ROT INST REV PH-1

Here are a couple of links to photos of the insides of the projector:

Thanks! I've done a bit of tinkering in the past, but nothing this complex.

Sounds like a Capacitor-run motor (which would have a constant speed for the movies). So probably difficult to control it's speed.

Stepper motors (generally) don't ran as fast as 3500 RPM.

Sounds like a DC motor that you can speed-control more easily and have enough power and RPM might be better. Maybe a heater fan motor, windshield wiper motor (gear train removed) or a radiator fan motor would work...


Experiment Time.

Good Luck. (In a thing like this it's almost as useful as Engineering)...

There are several solutions, but I think you would be pleased with a tiny 3 phase induction motor and an AC drive. So that the project does not become a slave to 240 volt power use a drive like this:

It will let you run 230 volt motor from a 110 outlet

You need to find a 3600 base speed motor. It will say something like 3480 RPM on the label. You can turn a tiny motor at 150% of rated speed with slight concern. Worst case you have to fine another one

The drive may have a voltage output signal to tell something else how hot to drive the lamp.

A big concern for the lamp, film and motor will be to keep sufficient heat going for cooling.

Watch Ebay for the motor. It will probably be part of something else. Maybe a Bodine gearmotor

I would go with a geared DC motor, maybe an electronically commutated brushless multiphase motor and an ESC would be a reasonable choice, then add a rotation sensor and write servo feedback logic in your Arduino code. A BLDC motor and ESC can be wired to the Arduino and operated with the servo library. A fairly simple one-pulse-per-revolution hall-effect or infrared shaft encoder can then be used to sense actual shaft speed. The "servo" part is then logic in the Arduino that measures the actual shaft speed, compares to the desired shaft speed, and adjusts the motor speed accordingly.

I neglected to look at the pictures before I posted above. Oops. I would leave the existing motor in place to provide cooling and add a motor to drive the mechanical mechanism. The mechanical part appears to be driven at 1/3 to 1/4 motor speed. This is important because a motor you find will likely be nominally rated at 1800 RPM. Operating within the motor specs it will be easy to over drive the mechanism with an 1800 rpm with the proper drive train.

The flat rubber belt is important. AC or stepper motors provide a rough input. DC motors are generally smoother but stiff. The input to the film shifting mechanism must allow for some flexibility in the drive system or all those nifty parts will suffer. What appears to be a metal input pulley is probably exactly the right amount of rotating mass to make the mechanism work just right when powered by the rubber belt.

Consider mounting the motor outside the cabinet, inline with shaft of the mechanical input or outside the cabinet, to the rear as viewed in the picture, with the new shaft parallel to the existing shafts. The inline mounting would be almost trivial. A C-face induction motor (face mounting) is a natural. The motor will have to be rated at two or three times the output of the present motor if it is to develop sufficient torque at very low RPM, say 1/4 hp.

Ebay auction # 390286282677 is about perfect. This is a rare beast. It will be heavier than you expect, so add a bracket, or better, a stiffener plate to the cabinet

I would mount the new motor to the case, to the right as viewed in the picture, with its shaft coaxial to the drive shaft, and connect the two via a rubber hose clamped over the shaft of the motor and the mechanical input shaft. The rubber hose would be a little flexible and compensate for minor misalignment. You should get it going in about an hour. grin.

Hi, I'm on the same project and I would like to know i someone have found how much is the MAX TORQUE that the projector need to run...

I've found some high torque motor here :

But i don't understand how much is the torque for the projector...



I know nothing about old old 16mm projectors, but i worked for years with 35mm cinema projectors and you absolutely could not run the film any slower without burning it. We actually had to be careful with bulb placement because at 24fps(each frame exposed to light twice for 1/96 of a second) the darker parts of film could easily get hot enough to burn. They also had massive flywheels geared up with LOTS of leverage so if you were to change the speed it would be very very very slow to react.

Im sure that may not even be an issue for a projector like this, but you ought to be sure. Just thought i'd mention it.