Power supply - Feetech Ultra high torque servo motor

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1

Hey there,

I have purchased a FEETECH Ultra-High-Torque, High-Voltage Digital Giant Servo FT5335M

At maximum torque it requires 9volt 7.4amp. In its current application it will be used to move a dial - barely any torque required. I am struggling to find an appropriate power supply that doesn’t require major custom modifications

Many thanks,

Torin

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2

Just run it at a lower voltage.

If your gauge needs to move quickly you should be ok to go with an underpowered supply and whack a big fat cap across the output (don’t forget a current limiting resistor as the cap will act like a short circuit initially). This will take care of momentary current spikes and just let your supply deal with the average.

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Hey there,

In the exact same position, how did you end up going?

Cheers,
Jack

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Hi Torin, Jack

Where did that come from. The data sheet I found when I used the link in the descriptive text indicates an operating range of 6V to 7.4V, no mention of 9V. Although most of it is written in Chinese and is typical of the data quality that comes from there. It may be a typo and you meant 7.4V and 9A, although the data sheed quotes a stall current of 6A at 7.4V.

What voltage are you looking for ??? MeanWell have a range of different types.
Here is an example from the web site. This model is listed as a desktop supply.

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Cheers Bob

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Hi Robert,

Thank you for getting back to me. I asked poloulo about this:

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Not sure if they are just being conservative to reduce accountability.

Do you think it is okay with a power supply current lower than the max current draw?

Also if I get one of those desktop supplies what method do you suggest to plug the cord in and distribute to the motor? is there an adaptor or something?

Thanks,
Jack

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You need to consider your application. If you are not loading the servo then it may never get to the maximum current draw. You should look at the servo specs to see what sort of current draw your intended usage will likely require. However, you also need to consider what spikes in load the servo might create, and what the power supply will do when overloaded. For instance, the PS mentioned above is quoted as “OVERLOAD 105 ~ 150% rated output power Protection type : Hiccup mode, recovers automatically after fault condition is removed”. Whether or not that is suitable also depends on your application, and in particular whether you are powering other devices off the same supply. The safest approach is obviously to go with something that is well above your worst case requirement, and it seems that the 9A suggested above is 50% above the stall current, which is a common rule of thumb. But that can get expensive. A proper analysis of the complete setup, including things like torque loads on the servo, start/stop operation, whether or not the servo can be stalled and other loads on the PS may enable the use of a unit that has somewhat less current capability.

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Hi Jack
I think maybe the reason allowing for stall current is regarded as important is if the servo is accidentally or purposely attempted to drive past the mechanical stops it would be in stall mode. So it would not matter what the operating current may be if it hits the stops for any reason it would be “stalled”.

I have not had a great deal of experience with servos so I may be wrong here and there may be some internal protection to cut or reduce power when the stop is reached. I don’t know but I personally tend to consider worst case and don’t get into too much trouble that way.

Jack. That example I posted above is just that, an example. Just to give you an idea what is out there. Work out what you need then search for a product to do that job. Not the other way around.

Looking at the pics that type of supply would appear to have something like a 2.1mm socket. The spec sheet for individual supplies will tell you. I believe there are adaptors available to convert this to screw terminal. I think Core stock something like this.

If you think or know you are going to have trouble with power supply “spikes” use a separate servo supply for the servo and keep a “clean” supply for the electronics. You only have to connect the grounds together. Randomly throwing capacitors (particularly large ones) around can be dangerous as any cap is a short circuit at switch on.
Cheers Bob

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