Need help expert guidance please

[Anil Khubchandani]

Hello all,
I am a doctor and hence not well versed with this field at all. However I stubled upon this educative forum while searching for a specific query.

I have an electrical massage chair (which was earlier powered by an Class2 transformer adapter supplied by the manufacturer-Input 110V 60HZ Output 24V 1Amp-I have a picture if needed).
With this, the motorised massage chair (with variable speed on remote) was working perfectly well.

I have relocated to a place with 220V input & also the bigger problem is that in this shifting I have lost the original 110V adapter mentioned above.

Can anyone suggest how to get this chair to be in use again.

The only power supply I could find was a 24V 3A adaptor (the laptop adaptor type) & the shops were insistent that 24V with anything more than 1Amp would work perfectly.

With my LITTLE knowlege of physics from college I find it difficult to beleive that 24V1A requirement
of Class2 transformer would work perfectly well even with a 24V3A laptop like adaptor.

I hope that someone of u can explain that since the 24V DC requirememnt matches it it OK to run the motor with 3Amps supply instead of the previous 1Amp supply of the previous transformer.

 

[FvM]

I agree with the suggestion. A 24V DC adaptor with 1 A or higher current rating should work, because it's essentially a constant voltage supply (similar to a 24 V battery) and the motor takes only the current it needs, usually less than 1 A.

The suggested replacement is surely a switched mode adapter, it behaves partly different than a transformer power supply, e.g. if the motor has a large inrush current. There's a certain risk that a switched mode adapter has problems to start the motor, but that's less likely a problem if the adapter has larger current rating. A practical test will be necessary in any case.

 

[Anil Khubchandani]

Thank u so much for the prompt reply.
I need a little more clarification from ur reply.
From ur reply, I gather that I can go ahead with testing the newly bought 24V3Amp adapter to work with the motorised massage chair. (the picture of the attempted replacement adapter is attached with this-Please see it if it is OK)

Is there any risk of damage to the motor/rollers in the chair (thats my only concern)
The adaptor cost is barely a few dollars (so it is immaterial)

Lastly I did not understand what u meant by "switched mode adapter"
Is it some modification to be made to this new adapter or is it something to be bought afresh.
Thanks

 

[Dan Mills]

That adaptor will almost certainally be fine.

Switched mode refers to the way that modern power supplies are made (using internal power switching devices to create a high frequency for the very much smaller transformer that can then be used), the old supply used a low frequency transformer which is larger and heavier but conceptually a much simpler component. It is pretty much an implementation detail.

Give it a go, I don't forsee a problem.

Regards, Dan.

 

[mtwieg]

A higher current adapter will certainly drive the motors. The only potential problem with a higher current rating is that the motor may produce quite a bit more torque when loaded. That could be a good or bad thing, but for a massage chair I doubt it's a big problem. If you're really worried about it, then you could put a 1A fuse in series with the motor.

 

[Orson Cart]

The 24V 3A adaptor will work fine, just make sure the + goes to + and the neg to neg,

Orson Cart, BE (E&E) power electronics engineer.