AC Switch - UK conversion

Hello from the UK,

I just received my Smart Home Kit and it is awesome. I was well aware that the AC switch was North American before I ordered, and I just figured i’d use my international power socket converters on it to get it working with UK wall sockets. But before I give this a try I just wanted to check with some better informed people whether this is a good idea. I’m not using a step down converter, so will the higher UK voltage fry the AC switch, or will it be fine?

Thanks for you help.

Just as a heads up, the A/C switch was only rated for ~120VAC, so there is a potential for harm to come to the device (which is why we cannot recommend using it at higher power).

So happy to hear that you’re a new Smart Home Kit owner though, and always excited to hear what our customers get up to with their new modules!

I have bought the Smart Home Kit from Europe.
I guess I need 2 of these devices to couple with the littleBits AC Switch

if you hover the mouse over the picture, you will see its label zoomed

Input AC110-120V 50/60Hz
Output AC220-240V 50/60Hz
and vice versa.

In spite of good reviews, I think the label is not clear. See this other product
Converts AC220-240 Volt 50Hz to AC110-120 Volt 50Hz
AC110-120 Volt 60Hz to AC220-240 Volt 60Hz

In fact, I guess to convert from one frequency to another, a more complicated apparatus is required such as
(see the first of the list which is rated to 100W as the previous ones)

I tried to understand what is the matter with these converters and found that we need to look at these formulas
particularly V=4.44fBmAcN10-6 (with V equal to applied [usually primary winding] rms voltage) and the Power handling capacity section.
You should invert above equation: N = V/(4.44
fBmAc*10-6) and consider what said in this other forum

A 60Hz transformer used on a 50Hz supply will be slightly over fluxed and heat up a bit more.

that is due to f being 50Hz in Europe, i.e. lower than 60Hz, and Bm is consequently higher (a lower f would require a higher N which we can’t fulfil in either the primary or secondary winding at a given primary to secondary voltage ratio).

Now read this other article

If you bring your electric alarm clock, assuming that it works on 240 volts, and set it at 6 pm when you check into the hotel, it will read only 11 pm when it is midnight, and only 4 am when it is 6 am. You will probably miss breakfast.

Therefore, not all appliances will be fine with a transformer which doesn’t convert frequency. In case of a clock radio, I guess it is a bare electronics matter. But there might be other situations where the (electrical) load type (reactive or purely resistive) and design can make a difference.

Finally, don’t forget the whole question is about power (handling/loss). See the above linked table about Core weight, gram / Current density, A/mm²

Power handling capacity of magnetic cores is affected by the required regulation, copper space factor and temperature rise limit. The permissible temperature rise depends upon current density, flux density, frequency, class of insulation, duty cycle and the heat dissipation capability of the transformer. That is why power rating cannot be specified precisely.

This is the reason why transformers/converters are limited in power and also why you will need the power rating of the transformer (before any frequency conversion) to be a bit oversized by design to avoid converting frequency at all without harm.

Maybe other more knowledgeable people can provide more insight because there is actually more on this topic such as the difference between traditional transformers and those working in switched-mode (internally operating at several kHz but still outputting a seamless 50 or 60Hz voltage).

I would stay away from trying to connect this to 220-240v until there is a European/UK one released.

You will at least need a step down converter to connect the AC switch to the UK 240v then a step up adapter to connect the output of the AC Switch (110v) back up to 240v to connect whatever it is you are trying to turn on and off (assuming whatever is connected isn’t able to operate off 110v).

Plugging a 110v device into 240v will most likely fry the AC switch or short your fuse box. Trying to power a 240v appliance with 110v output, that does not operate within a 110v-240v range, will most likely not work or possibly, if for example in the case or a light, provide much lower output…

Wouldn’t recommend it at all at the moment though.

Cheers, Dan

I’m from sweden, eager to make this work as well. Has anyone tried hack this one so it works for 240V?
Are there any other AC switches that will work with the LittleBits IR transmitter? (

The AC Switch from littlebits are manufactured by an chinese supplier called C-Union. It is also available in 240V:

No idea how to buy only one though.

One thing that I’ve found out is that these IR sockets are pretty rare on the market. For security reasons Remote AC Switches are radio controlled, operating at 433MHz. Please give a shout if you’ll find a 38khz AC switch on like amazon. I’ll happily try it out.

If you do NOT have a step down, it WILL fry a 120VAC rated system. I had a colleague from IBM (USA) fry the only working version of a prototype at a trade show in Germany by not remembering to switch the AC power from 110V to 220V on the back of the system. Needless to say, the press corps were none to impressed.

So, does anybody knows if LittleBits have any plan to manufacture international power supplies for their kits?

Hi @fcathala,

Are you referring to the AC switch as part of the smart home kit?

See following topic with additional information for you about this switch…
I asked same question a few months ago, at that time they had no actual plan to make international versions.

Referring to the power bits used for Littlebits:
They are quite international, you can use any local wall socket power plug as long as the output voltage is 9-12 Volt DC. (and the connector must fit…)
The power bit for USB connection is fully international, any local USB charge unit can be used, but when many bits are connected, the charger unit must be able to supply a current of appr. 2 Amps.
Hope this info will help you. :slight_smile:

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“2 Amps” on a USB charger that’s the information I was after. It’s for the CloudBit but I guess it’s the same device from LittleBits catalog.

Many thanks @alexpikkert! :smile:

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Hi @fcathala,
You guessed right !
The official US USB charger unit can supply 2.0 amps at 5 V.
The Cloudbit and the servos are consuming a lot of energy.

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Here is a good target for a 'dream bit"! An IR activated, AC switch with variable AC parameters(using switches?) that could confirm to multiple specifications (US, UK, etc, ) is a sure winner, right? Add your affirmations, suggestions and commitments here so that it will get made!

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Hi @chris101 @fcathala,
Unfortunally it is not only the AC voltage level.
Also the shape of the contacts is different.
In spite of many standardization committees we humans never succeeded in making a real standard wall plug design…
There are 15 (fifteen !) different designs and two different voltages (US, Canada, Mexico an Japan use 127 V AC and the rest of the world uses 240 V AC.)

Earlier I suggested to the Littlebits team to redesign the AC switch for 240 V AC and plug type C and G to cover 99% of Europe…
But this is not (yet) on the development roadmap…
FYI @Patrick_littleBits

This is an old topic but does not seem to have been resolved.

I am wondering whether this product would fit the bill for a UK IR-controlled AC switch:

The product instructions describe a pairing process that appears to be identical to the one for the LittleBits AC switch.

Can anyone advise?

Hi @guymo,
The IR controlled AC switch I am using is also not the official USA thing but a different dutch version and it reacts (after pairing) on a signal from any brand of remote control. It was sold as a so called “standby-killer”.

Your UK switch does the same I think acc to the specs in the link so I think it might work also.
The Littlebits IR transmitter sends (up to four) specific signals equal to a signal of a standard tv remote.
If you try using it, let me know the result… :grinning:
maybe Littlebits team has more info ? @sean_littleBits ?

Home Depot sells manual transfer switches that will safely and legally allow you to select mains power or gen power. here is International Plug Adapters you can see