Hi guys,

This is more an electrical question. I've two Vibro Graver electric engravers (120V 60Hz) with me. I gave one to a friend who recently moved to another country. He got a step down converter to 110V but then he noticed the frequency used there is 50Hz.

What would the effects of using the device on a 110V 50Hz supply when the device is meant to be used on 120V 60Hz supply. Does the 10Hz difference cause any damage?

 

It may make no difference or it may destroy the device, possibly catastrophically. Pretty hard to tell since we don't know whether or not that device was designed to operate on both 50 Hz and 60 Hz (many devices are) or not. In general, transformers and inductors are pretty sensitive to significant changes in frequency (and 10 Hz out of 50 Hz is a 20% change which is pretty significant), but the design may or may not have allowed for it.

 

Another possible problem is that the vibrating thing may be resonant at the 60Hz it was designed for and so may not work well at 50Hz.

 

It may make no difference or it may destroy the device, possibly catastrophically. Pretty hard to tell since we don't know whether or not that device was designed to operate on both 50 Hz and 60 Hz (many devices are) or not. In general, transformers and inductors are pretty sensitive to significant changes in frequency (and 10 Hz out of 50 Hz is a 20% change which is pretty significant), but the design may or may not have allowed for it.

The device says only 60Hz as shown in second picture. This is what I too was worried about. I'm not sure how the thing works. If its a motor inside or just an electromagnet vibrating. Also how the inductors react to frequency changes.

 

Hello,

I think there is a vibrating needle in a coil.
The knob for stroke will adjust the spring on the needle.

Bertus

 

I would guess that if there is a motor in there, it is a Universal model, if so 50Hz will not matter.
If that is a vibration/speed control, then it would almost confirm it, as it is most likely a Triac controller.
If a vibrator model, then also it should not matter as the impedance changes anyway with variation in speed.
Max.

 

I would guess that if there is a motor in there, it is a Universal model, if so 50Hz will not matter.
If that is a vibration/speed control, then it would almost confirm it, as it is most likely a Triac controller.
If a vibrator model, then also it should not matter as the impedance changes anyway with variation in speed.
Max.

Hi,
Isn't a universal motor one with a carbon brush that can be used with both AC and DC? Also the tip doesn't rotate when I checked now. It just oscillates really fast when pressed against a surface and the motor vibrates really fast when reduced to lower values.

 

The vibration speed will be that much lower probably on lower frequency, depends if what method is used to vary, mechanical or electronic.
Max.

 

The vibration speed will be that much lower probably on lower frequency, depends if what method is used to vary, mechanical or electronic.
Max.

The speed/ vibration adjust knob seems to be a screw in type with a spring attached. Its a very old device too. Model is Vibro graver V-74 (built around 1980s I guess). So its definitely not the new electronic kind for sure. I had a pair so I'd given one to my friend.

 

So the switching frequency is being varied anyway!
Max.

 

So the switching frequency is being varied anyway!
Max.

It likely works like an electric hair clipper “motor”. The screw only adjusts the throw (travel), not the frequency.

Run it for 3 seconds then 10 seconds, 30 seconds, ... and have him feel if it is heating excessively (or blowing a fuse) after each run.

The 50 hz vs 60 hz means the inductive reactance from the motor will be less and allow more current to flow. Inductance may be so great that the change to 50hz is minor. It could also mean that the increase will blow the motor (or melt the enamel insulati9n in the coil).

Alternatively, have him check if replacement coils are available in his country (they should be set up for 50 Hz).

 

Lived in Italy for a number of years. Wife at the time had a 120 Volt 60 Hz massage gizmo. Had a screw adjustment for the travel or throw. Using a transformer it ran fine for a few uses and then one day there was a pop and puff of smoke. On a side note I bought a huge (well by Italian standards) 17 cubic foot refrigerator from a GI getting a divorce. Ran that off a larger transformer and that thing worked just fine for the three years that I had it. The compressor and fan did fine on 50 verse 60 Hz. The vibrating gizmo, not so good.

Ron

 

It likely works like an electric hair clipper “motor”. The screw only adjusts the throw (travel), not the frequency.

Run it for 3 seconds then 10 seconds, 30 seconds, ... and have him feel if it is heating excessively (or blowing a fuse) after each run.

The 50 hz vs 60 hz means the inductive reactance from the motor will be less and allow more current to flow. Inductance may be so great that the change to 50hz is minor. It could also mean that the increase will blow the motor (or melt the enamel insulati9n in the coil).

Alternatively, have him check if replacement coils are available in his country (they should be set up for 50 Hz).

Yes, you are right. I did some research and found what you said to be right. Running a 60Hz device on 50 Hz supply pretty bad and it will draw more current which will overheat the device and ruin it. He did run a few tests and he said it was way louder and not working as it should and getting warm really fast.

 

So, the solution he has come up with is since frequency convertors are expensive he is planning on something like a 12V DC to 120V 60Hz US supply inverter. He has a few appliances that run only on 120V 60Hz and this might help him.

https://www.amazon.com/dp/B074DV8YKJ/ref=dp_sp_detail2?psc=1

https://www.amazon.com/Reliable-2000w-Inverter-Display-Solar/dp/B01114J6T4

 

Something that still bugs me is as how do voltage conversion 110V/220V to 220V/110V reversible auto-transformers work at both 60/50Hz without any overheating as its also an inductive device.

 

Because they are designed to cope with both frequencies. This may make them slightly more expensive and/or slightly less efficient but makes them more universally useful.

 

Because they are designed to cope with both frequencies. This may make them slightly more expensive and/or slightly less efficient but makes them more universally useful.

Hi,

So does it mean that their no of windings or the thickness of their laminations are different?

 

I don't know the details of their design. The problem is using a transformer designed for 60Hz on 50Hz, so maybe they are designed for 50Hz but can cope with 60Hz?

 

I don't know the details of their design. The problem is using a transformer designed for 60Hz on 50Hz, so maybe they are designed for 50Hz but can cope with 60Hz?

Yes. I know that some devices like the one mentioned in my original post can run only on a particular frequency. The auto-transformer I mentioned is something like this in the pic attached. Maybe they can cope up with. I was curious about what design changes they might have adopted to work on both.

 

Yes. I know that some devices like the one mentioned in my original post can run only on a particular frequency. The auto-transformer I mentioned is something like this in the pic attached. Maybe they can cope up with. I was curious about what design changes they might have adopted to work on both.

The purely inductive load of the circuit is “inductive reactance” (in ohms) is (6.28 x frequency x inductance).

Your vibratory motor operates the same way as a hair clipper “motor”. Note from the above that the load “resistance” is reduced by 17% if 50 hz is used (at 120 vac). That means 20% more current flows. Bu, since the motor is designed for 60Hz (see video), the required current flow to pull the flapper into the. Ore (see video) happens much earlier in the since wave cycle and the core saturates at the current from the 60Hz frequency and he whole design falls apart. Then, all of the additional current flow directly becomes heat.

Also, the spring to push the flapper away from the core at each cycle is not tuned to the right tension so the flapper stays attached to the core too long and it just doesn’t get the right duty cycle and further falls apart in terms of design efficiency.

A wall adapter that can work on any frequency is a switch-mode power supply and operates on a different principle. That I am runn8ng out of time to explain.