240V to 120V Step-Down Transformer  - Page 1
Forum section: electronics / beginners

author: bigbadwolv
author_rank: Newbie
timestamp: December 06, 2019, 09:59:27 pm
content: Hi all,Please feel free to move this if it isn't in the correct place (I just figured it is a rather n00b question).I am from Aus, and recently purchased a robot vacuum from the US (Shark IQ R1001AE). I stupidly assumed that it would be like many other products and accept both 120V and 240V. Now I am in the predicament of needing a 240V to 120V Step-Down Transformer. The dock (according to the label) requires input of 120V 60Hz 650W.These shouldn't be too difficult to find but I want to make sure what I purchase is both safe for the device and my family. Can you recommend any reputable brands or products?I hope I gave all the info required. If not please don't hesitate to ask for the details required.TIA, Wolv

author: andy3055
author_rank: Super Contributor
timestamp: December 06, 2019, 10:53:06 pm
content: You will be better off buying one in Australia rather than lugging it from here. All you need is something that is either 650 Watt or higher, given the charger draws 650 Watt.

author: tunk
author_rank: Super Contributor
timestamp: December 06, 2019, 10:56:18 pm
content: You might be able to modify it:https://www.eevblog.com/forum/beginners/converting-a-cordless-drill-charger-%28hitachi-uc18yksl%29-from-110v-to-220v/

author: Zero999
author_rank: Super Contributor
timestamp: December 06, 2019, 11:23:27 pm
content: A transformer won't change the frequency, although that shouldn't matter.I can't recommend any specific brands. I'd just go to a known good electronic/electrical distributor and buy one. An autotransformer will be fine, since it doesn't need isolation and will be smaller and cheaper than an isolating transformer. It would be a good idea to use a transformer with a slightly higher power rating than the vacuum, just to be safe, so 750VA or bigger will be fine.

author: james_s
author_rank: Super Contributor
timestamp: December 06, 2019, 11:52:27 pm
content: 650W?? Surely that's a typo? My Roomba charging docks draw at least an order of magnitude less than that.

author: bigbadwolv
author_rank: Newbie
timestamp: December 07, 2019, 12:51:38 am
content: Thank you all for the input so far!Quote from: andy3055 on December 06, 2019, 10:53:06 pmUnfortunately, they aren't available in Aus, which is why I lugged it from over thereQuote from: tunk on December 06, 2019, 10:56:18 pmTrue, but I don't think I'm going to play around with it at this stage - just want a simple solution that I can't really stuff up!Quote from: Zero999 on December 06, 2019, 11:23:27 pmThanks for the info, only posted the frequency in case it was relevant. I'm hoping that the difference between 50Hz (here ins AU) and 60Hz (in the US) shouldn't make too much of a difference.Quote from: james_s on December 06, 2019, 11:52:27 pmYeah I thought the same - I have been in contact with their support, awaiting a response from someone technical...

author: langwadt
author_rank: Super Contributor
timestamp: December 07, 2019, 01:45:41 am
content: Quote from: james_s on December 06, 2019, 11:52:27 pmmaybe it has a motor for a vacuum to empty the robot?

author: andy3055
author_rank: Super Contributor
timestamp: December 07, 2019, 01:54:37 am
content: Looks like this has a self-emptying feature that has a separate motor in the charging unit. That may be why it draws so much. Never seen one like this but they seem to make things more and more feature rich!Your best bet may be to get a suitable transformer and make your own box with a US type outlet.

author: james_s
author_rank: Super Contributor
timestamp: December 07, 2019, 05:26:46 am
content: Ah, well that could explain it. If that is the case then a triac dimmer type circuit ought to work for the motor, every mains powered domestic vacuum I've seen has a universal motor that ought to work fine on one of those. Then you could look at the power supply for the rest of the unit, it may be easily converted to 240V, or replaced with a similar spec power supply.

author: bigbadwolv
author_rank: Newbie
timestamp: December 07, 2019, 06:51:36 am
content: Quote from: andy3055 on December 07, 2019, 01:54:37 amQuote from: langwadt on December 07, 2019, 01:45:41 amI believe Andy is correct the dock does have an auto-empty feature which sucks the crap out of the robot - I assume the motor is in the docking station.Thank you for the responses - I will have to have a look into the proposed solutions and see which way I want to go.