projection speed change between 50Hz and 60Hz

[Floris Vanhoof]

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.

[Mark Gulbrandsen]

That's not a model I have ever heard of. In the USA, B&H used numerical numbering on it's 16mm models. Like 1564 and so on. The older projectors had lower numbers. Anyway, a picture or two may help, but I even searched B&H variable speed projector and nothing came up, so it may be a conversion done by someone in Europe. Here in the States all the vari-speed projectors I saw and repaired were Kodak Analysts. I have attached one that is on EPay.

[Floris Vanhoof]

the model is b&H TQ3 1698

[Jim Cassedy]

Very interesting question, Floris!
Mark- The TQ3 is cosmetically identical to the B&H " 1500/1600" Series here in the US. The main difference is the
addition of a voltage selector switch, which I think is mainly to switch the primary side of the transformer that powers
the projection lamp and amplifier. But since the US versions of these had synchronous motors, I have no idea how it
would handle the 50/60hz issue, unless the motor has two different windings or without changing the motor pulley.

. B&H_TQ3.jpg

[Mark Gulbrandsen]

Very interesting question, Floris!
Mark- The TQ3 is cosmetically identical to the B&H " 1500/1600" Series here in the US. The main difference is the
addition of a voltage selector switch, which I think is mainly to switch the primary side of the transformer that powers
the projection lamp and amplifier. But since the US versions of these had synchronous motors, I have no idea how it
would handle the 50/60hz issue, unless the motor has two different windings or without changing the motor pulley.

. B&H_TQ3.jpg

It could only be done with a pulley change. Anyway, he did not really provide enough info such as FPS he uses and weather or not he uses it in a vari-speed mode. But seeing that pix tells me he is only interested in 16 fps.

[John Eickhof]

I doubt it is a poly-phase motor, and like mark said its probably synchronous, thus if it is set u for 50hz a pulley change will be necessary for proper sound speed otherwise if running silent it wont matter except for the show running slightly faster...i would open it up and look at the motor or main belt pulley, there may be a second groove where you slide the belt over for 60hz vs 50hz

[Steve Guttag]

I'm not familiar with that specific projector but I've dealt with many 16mm projectors that had two-groove motor pulleys (and the mating pully on the shutter or drive shaft)...to switch frequency, one just moved the belt over to the other grooves.

[Floris Vanhoof]

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.

From the manual it looks like it's a DC-motor.
http://www.film-tech.com/warehouse/manuals/BHTQIII.pdf

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

[John Eickhof]

specs indicate the tq III series is rated for 50 and 60 hz use ,without any user adjustments, ( you may have to adjust the trim pot to get your desired speed however) I looked at the schematic and it utilizes a shunt wound DC motor with a variable speed control, thus the line frequency is of no issue, yes it will work in N. America by only setting the proper line voltage and having the correct mains plug. Have fun! It's not every day you will see a traveler carrying a 16mm projector around! It will be a challenge explaining to the airport officials that it is a digital-analog display device!!

[Mark Gulbrandsen]

I'm projecting at around 10 fps.

How is the flicker at 10 FPS?

[Floris Vanhoof]

As I'm looking for the odd effects described below, I find the flicker at around 10fps very nice.


R.L. Gregory - Eye and Brain

Film projectors have a special shutter which shows each picture 3 times in rapid succession,

so that although the number of pictures shown is only 24 per second, the flicker rate is 72 flashes of light each second.

Low-frequency flicker produces very odd effects. At flash rates of about 5-10 per second brilliant colours and moving and stationary shapes may be seen and can be extremely vivid.

Their origin is obscure, but they probably arise from direct disturbance of the visual systems of the brain, the massive repeated bursts of retinal activity overloading the system.

[Stefan Scholz]

The ones I repaired for the port exchange service in the 80s had a low voltage DC (tacho-generator controlled) motors, that worked on any mains frequency. And yes, the power transformer had
different voltages to choose from.
The one that my friend from N.Y. state gave me had a (a?) synchronous AC motor, running at 120 V mains. Plus the lamp was also 120 V mirror. The machines for the ships used 24 V / 250 W bulbs of similar body shape. So there was a low voltage transformer, feeding lamp, motor, and amplifier.
The TQ 3 was universally usable all over the world, the U.S. 120 V version only in 60 Hz 120 V networks.

Probably, he also has one of these. Which would make speed variation easy.

[Stefan Scholz]

IMG_20230225_100727[1].jpg
Motor circuit of the "TQ" models. Motor is 24 V DC with alternator to control speed. It works on any frequency (40/50/60/400 cps). So beyond land networks it can be used in aircraft (400 Hz) and some ships (40 Hz). Most ships today use 60 or 50 frequency, depending on area of main use.

[Emiel de Jong]

As I'm looking for the odd effects described below, I find the flicker at around 10fps very nice.


R.L. Gregory - Eye and Brain

Film projectors have a special shutter which shows each picture 3 times in rapid succession,

so that although the number of pictures shown is only 24 per second, the flicker rate is 72 flashes of light each second.

Low-frequency flicker produces very odd effects. At flash rates of about 5-10 per second brilliant colours and moving and stationary shapes may be seen and can be extremely vivid.

Their origin is obscure, but they probably arise from direct disturbance of the visual systems of the brain, the massive repeated bursts of retinal activity overloading the system.

Did you modify the shutter as well? Because normally 16mm projectors have a 2 blade or 3 blade shutter, or switchable. So when you run 10fps you actually get 20 or 30 flashes per second.

[Floris Vanhoof]

I didn't change this yet