I'm going from Belgium (230V 50Hz) to the US and Canada (110V 60Hz) with my Bell & Howell TQ3 projector.
I can use the onboard voltage selector switch to go from 230V to 110V,
but will the frequency be 50Hz or 60Hz?
And will this affect the motor speed?
I'm using the motor at the lowest possible speed, so re-calibration is not an option here.
All help welcome!

I don't know about that particular projector, but most projectors with A/C motors have separate pullies for the belts for 50 hz and 60 hz. It is just a matter of switching the belt to the correct pulley, which in the U.S. is 60 hz. Your projector has an A/C motor, according to this:

https://ian-partridge.com/b&h_tq3.html

Since it says it supports both 50 hz and 60 hz, take the back cover off and look for the pullies. If there are not alternate pullies, look to see if there is some other frequency switch. It is hard to tell from this pic:
https://van-eck.net/img/itable/images/fi...61599114145.jpg

Since it is not a D/C motor, but an A/C one, there has to be a mechanical change rather than an electric one to support the correct speed for both frequencies.

Take a look and let us know.

Both Canada and the USA have power rated at 60 Hertz.
Your Bell & Howell TQ3 projector will run 20% faster on an 60 hertz supply.

Quote: Maurice Leakey wrote in post #3

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Both Canada and the USA have power rated at 60 Hertz.
Your projector will run 20% faster on an 60 hertz supply.

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I'm projecting at around 10 fps.
This speed is obtained by adjusting one of the speed calibrating trimpots inside the projector to the minimum speed.
By turning this trimpot, one can also continuously adjust the speed.
I filmed at 10 fps too.
In my EIKI projectors there's a belt that needs to ben changed to adjust speed. I don't think the B&H TQ3 1698 has those.

Here's the service manual
http://www.acofs.org.au/part_5_files...,2590,2592.PDF
maybe somebody here understands the schematics better then me.

The Bell & Howell 1698, under normal conditions, alters speeds electrically by a sliding switch at the rear near the mains input.
It is marked <18 24> .
As Floris says, Eiki projectors can effect speed change by moving the drive belt to another set of pulleys, but not this Bell & Howell, nor its brothers, 1692, 1693, 1694 and 1695.
.

Seems like it's a DC motor from this manual:
http://www.film-tech.com/warehouse/manuals/BHTQIII.pdf

Can anyone confirm that DC-motors of film projectors will run at the same speed regardless of the change from 50Hz to 60Hz?

Sorry, I misread this: https://ian-partridge.com/b&h_tq3.html when I saw A/C. They were referring to the mains supply, not the motor.

Yes, on my Yamawa Super 8 machines, there are 2 potentiometers in order to change the speed: one for 18 fps, and the other for 24 fps.

Now I understand your question more -- you have the potentiometer turned all the way to the lowest voltage setting already. I assume it is the 18fps one if you are running at 10fps.

My 20,000 feet understanding is that DC motors change speeds according to the voltage supplied -- which is what changes when you adjust the potentiometers. According to this: DC motors have no frequency.

https://electronics.stackexchange.com/qu...ffect-dc-motors

When you make the voltage change on the transformer when you are in U.S./Canada, it will supply the same voltage to the motor as it did in Europe. But since mains supply voltage fluctuates (even within the U.S.), you may still have to adjust the potentiometer again to achieve 10fps. In other words, your mains supply could be 115v, for example, or 122 volts.

How many different voltage options are available on the transformer? On many of my projectors, there are options for voltages like 110, 115, 117, 120, 125, for example. 117 volts seems to be a popular setting usually recommended. The LOWER the voltage setting you use on the transformer, the HIGHER the voltage supplied to the projector will be -- meaning, for example, you will get a BRIGHTER light from the lamp, which will SHORTEN the lamp's life, and the motor will run FASTER. In your case, since the problem may be to get the machine to run slower, you may have to set the voltage on the transformer HIGHER, which will make the motor run SLOWER, make the lamp DIMMER, but EXTEND its life. So you need to balance the transformer setting with the potentiometer setting to adjust the motor speed, while considering the lamp brightness and life.

The best thing to do is have an electrician check your mains supply when you get to the U.S/Canada, and set the transformer to the closest possible value greater than or equal to the reading he gets. At least to start out with.

I have heard people say that here in the U.S., our voltage can fluctuate throughout the day. So in theory at least, a projector with a DC motor could change frame rates as your watching a film! In practice, I have not had that happen with my sound machines with DC motors, where it would be very noticeable. :)

It appears that DC only flows in one direction. So it is zero Hertz.
https://www.toppr.com/ask/question/the-f...-current-dc-is/

thanks for the help!

I did some more research out of curiosity. Apparently capacitors attemp to keep voltage constant, so perhaps that's why I haven't noticed any speed changes while using my projectors with DC motors, assuming the mains supply voltage was fluctuating. I have observed brighter light when lowering the transformer's voltage setting, however.

(Funny how college physics was so focused on Calculus rather than teaching us things we would find practical later in life!)


In any case, the bottom line is that your projector obviously supports the lower voltage, and we will have to see what the outcome is when you adjust the transformer voltage, the speed potentiometers, and plug it in to a watch a film.

Good luck!

I'm just back from 7 screenings in Canada and the U.S. and glad the speed stayed the same.
I was especially happy that the throw in a 300+ seat theatre in Montréal was still ok.
The rest were smaller venues and in Brooklyn, NY the projector was standing on a ladder to shine over the heads of the standing audience.

For my next series of shows I’d like to build a single blade shutter into my B&H TQ3 16mm projector. I'll start a new topic for this.

Quote: Floris Vanhoof wrote in post #12

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I'm just back from 7 screenings in Canada and the U.S. and glad the speed stayed the same.
I was especially happy that the throw in a 300+ seat theatre in Montréal was still ok.
The rest were smaller venues and in Brooklyn, NY the projector was standing on a ladder to shine over the heads of the standing audience.

For my next series of shows I’d like to build a single blade shutter into my B&H TQ3 16mm projector. I'll start a new topic for this.

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a club called CC in Greenpoint
here's a site that announces this kind of shows:
https://nyc-noise.com/