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I recently got my hands on a Philips PM8110 (a single pen recorder which is basically an analog printer for voltages) which sadly provides paper with a velocity of 8 cm/hour. Although this would be ideal for measuring temperatures of the environment, it's not really efficient for what I want to use it for (toying around with it since this is an old inefficient technology but I just love the device). Now, I figured out that the paper supply is driven by a synchronous motor which, when supplied with a 50 Hz 100 V signal (supplied from wall via transformer) rotates once per hour.

Since I want to increase the paper speed to around 8 cm/min, I would need to supply the synchronous motor with a 3000 Hz signal [a high accuracy is not really required].

Question 1: Not looking at how to obtain this signal yet, is this even a possible method? Can the synchronous motor even handle such a huge increase in frequency?

Question 2: Suppose the answer to question 1 is yes, how can I multiply the incoming frequency by 60 (or about, so it might become x64 if multipliers would be used). Is there an IC for this? In the ideal situation, I would like to keep this motor (since it's the original) and with a switch, switch between the original 8 cm/hour to a side with a potentiometer for a variable paper speed. I looked on the internet of course but could not find a definitive answer on whether or not there is actually a really simple, small, realizable method.

I guess that if the answer to question 1 is 'no', I would have to search for another motor with the desired rotational velocity (whether this would still be a synchronous motor or not) and install it in the device which, as mentioned previously, is not preferred. Any other methods or some inspiration is also really appreciated.

I would love to get some insight into this,

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You cannot expect to increase the speed of rotation of your synchronous motor by 60x. In addition your paper drive is most probably a motor and gearbox combination; so NOT just a synchronous motor.

You have not specified the number of poles in your motor, so it's hard to guess at what the actual shaft speed is. You can look here for more information.

enter image description here

Notice that in the above table you are talking about raising the speed of a 12 pole motor from 500 rpm to 30000 rpm. You can guess whether that would be successful.

Your best bet is to replace the motor/gearbox with a new one. While you could look for a synchronous motor for this task, your best possibility would be to replace the motor/gearbox with a stepper motor with no gearbox (much less engineering to do). With a stepper motor you can get controllers that will drive the shaft at up to 256x microsteps and the feed rate is then defined by a simple to generate pulse frequency.

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  • \$\begingroup\$ And once you get the paper going faster, you may well find that the bandwidth of the pen drive isn't up to maintaining accuracy. I suspect it will, because they probably had other models that did go around as fast as you want (probably with the same motor but a different gearbox). \$\endgroup\$ – TimWescott Oct 20 '18 at 16:31
  • \$\begingroup\$ I would see if I could replace the motor/gearbox with my own stepper motor & gearbox (with less reduction), and a suitable controller. \$\endgroup\$ – TimWescott Oct 20 '18 at 16:31

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