Step Down Transformer advice needed please

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Satch

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#82570 2-May-2011 12:46

Hi,

I'm looking to purchase a Boston Acoustics Duo-i Plus iPhone radio alarm clock dock (http://www.bostonacoustics.com/Duo-i-plus-AMFM-Stereo-Radio-with-iPhone-iPod-Dock-P393.aspx) as it fits all of my requirements bar one.

The one that falls down is that it does not support 230v. There seems to be next to no info that I can find on the Internet regarding its power requirements, so I ended up contacting Boston Acoustics directly. This is all the info I have been able to get from them:

"The unit needs 120v 60Hz @ 2Amps"

My question is, what sort of step down transformer will I need to operate the unit here in NZ? I really have no clue on this one.

Cheers.

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#464482 2-May-2011 13:56

Dick Smith Product M9760

Thats quite a high current (for an alarm clock) so you need the largest of the three step down transformers that dick smith stock. At $249 for the transformer you might want to look at a different alarm clock!

edge

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#464483 2-May-2011 14:01

Or Jaycar CAT. NO. MF1082. $155 if you buy one only. As noted above, 2 amps seems pretty high draw for this device - can't find any specs on power output etc for Duo-i Plus but 2 amps is around 230W power draw. Having said that, its worse than useless having a transformer that won't deliver sufficient current.

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timmmay

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#464485 2-May-2011 14:16

I bet it uses nowhere near 2 amps. That's 10% of the maximum power you can draw from a wall socket! It probably uses milliamps in standby, and hundreds of milliamps when it's on really loud.

You could always get the dse transformer and measure how much power it really needs, and swap it for a smaller one. Alternately if it has an external power supply just replace it.

edge

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#464488 2-May-2011 14:36

timmmay: I bet it uses nowhere near 2 amps. That's 10% of the maximum power you can draw from a wall socket! It probably uses milliamps in standby, and hundreds of milliamps when it's on really loud.

You could always get the dse transformer and measure how much power it really needs, and swap it for a smaller one. Alternately if it has an external power supply just replace it.

Yep - intuitively wrong - but, as a matter of interest (slow day at work) I have had a look around the interwebby thing and cannot find anywhere in the documentation about a 110/220(or 240V) switchable power supply (incidentally it is an internal supply so a simple swap-out won't work in this case).

What is strange is that it is available in lots of parts of the world (incl UK) so one would think there was either a switchable power supply or a model for 220/240V markets?! OP could always call Avalon Audio (local distributors) to check - although I'm guessing it might be cost causing the look at one that apparently runs in 110V only?

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gzt

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#464500 2-May-2011 15:06

Agree with timmmay. That figure is about the same as a small crt tv.

But, there are cheaper options on trademe, so it may not matter.

By the way, if you are lucky, the boston may have an internal power supply transformer which is easily replaced with something for 240v in NZ.

I do wonder about the line frequency though. US 60hz vs NZ 50hz. A stepdown transformer won't change this of course. Switchmode powersupplies like we get for computers and cellphones are designed for multivoltage and multifrequency, but I'm not sure if smps designed for a single voltage are happy operating on a different frequency. Anyone have any experience with that?

I would guess the boston has an inbuilt transformer and dc conveter, rather than an smps, so stepdown should be fine. But this is just a guess.

Satch

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#464818 3-May-2011 12:17

Thanks everyone for your input. Really shows to me that I have no idea...

Here are the two responses I received from BA Technical Support in the US:

"The unit if bought in the States will not be compatible with 220/230 voltage"

and

"The unit need 120V 60Hz @2Amps"

Is it worth me questioning the Amps requirement if it is that questionably high? If so, what would be a suitable question that made sense?

gzt

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#464823 3-May-2011 12:36

Satch: Is it worth me questioning the Amps requirement if it is that questionably high?

Probably not. The best you could hope for is that they are reading the power sticker on the back of the unit. Maybe go and see the NZ one somewhere and confirm what the NZ sticker says. Probably the same thing - 1 amp @ 240v (= 2 amp @ 120v).

Satch

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#464828 3-May-2011 12:40

gzt:
Satch: Is it worth me questioning the Amps requirement if it is that questionably high?

Probably not. The best you could hope for is that they are reading the power sticker on the back of the unit. Maybe go and see the NZ one somewhere and confirm what the NZ sticker says. Probably the same thing - 1 amp @ 240v (= 2 amp @ 120v).

I'm not even sure they sell it in NZ. I did contact Avalon Audio asking them about the power requirements, but they obviously didn't see any worth in replying to my email...

BS

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#464833 3-May-2011 12:50

Have you had a look at the reviews on

reviews.cnet.com/radios/boston-acoustics-duo-i/4505-7875_7-33777020.html#reviewPage1

one of the reviews mentions that there's lost 45 minutes and he was nearly late for work, maybe the frequency is important, cant see why though, as for the power requirement I think the have missed out a decimal point. 140w "wow" I know the Americans have no concept of energy conservation but 2amps at 120v they have to have made a mistake.

Bryan

Satch

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#464838 3-May-2011 12:56

Thanks for the input BS. I might just email BA back to question the 2Amps part now.

As for the 45mins lost time, I've read a number of reviews and this is the first that mentions this issue. Not sure if it is a common issue or not...

richms

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#465373 4-May-2011 18:42

Any cheap clock from the US will lose time on 50Hz power. Also you _may_ have excess heating in its transformer but usually they dont downsize them to the point that is a problem.

If you are lucky it will have a transformer with 2 primarys that can be rewired in series to get it running on 230, and there is a pin on the clock chip in cheap alarm clocks to change it to work on 50Hz if you can be bothered.

However if its a custom microcontroler design then all bets are off, it could be a different firmware load for the different markets to account for date and time formats and powerline frequancy.

IMO bringing in an average at best ipod dock and dealing with all those hassles is foolish.

Richard rich.ms

Satch

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#465606 5-May-2011 09:33

richms: ...IMO bringing in an average at best ipod dock and dealing with all those hassles is foolish.

I take it you've used a Duo-i Plus before to be qualified to make this statement? What in your experience makes it average at best?

I do agree with you though that the hassles are making it a foolish exercise. I'd really want to do no more than import it, purchase a cheapish step down transformer, and plugging it all in. I may have to look at different options. Looks like it is time to open another thread...

richms

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#465836 5-May-2011 16:41

It only passes composite out from the iDevice, it has a cheap low constrast non TFT type LCD on it, IME those are damn hard to read off axis and have an unacceptable amount of light leakage, particually when used with a blue backlight.

It doesnt mention if it uses the iDevices analog output or does it digitally, but I strongly suspect its just analog. No mention of what control over playlists etc you have for wakeup.

Its nothing flash but as it has a iDevice slot on the top of it they can add another 100 to the price of something not special.

Richard rich.ms

lchiu7

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#465850 5-May-2011 17:16

richms: Any cheap clock from the US will lose time on 50Hz power. ...

Who would make a clock integrated into some other device (like a radio) that would rely on mains frequency for setting the clock these days. Mains frequency is so dodgy and it must be cheap as chips to have a crystal oscillator that sets the time.

Many moons ago I brought back a turntable from the US. Many of them relied on mains frequency and you could often adjust the speed use a strobe disc that had radial lines that would appear stationary when the turntable was rotating at the right speed under the illumination of a 50Hz light. But that US turntable worked fine with a stepdown transformer and 50Hz so it certainly wasn't relying on mains frequency for regulation.

If this iPod dock needs 2 amps, that is about a max of 440W (actually less since we are talking AC current here so would probably have to do some sort of RMS calculation), That's pretty substantial since I run a 7.1 HT receiver (US origin) on a 500W transformer and the transformer doesn't break a sweat.

If the OP's heart is set on this device, I would just get a 100W transformer from DSE or TM and try it out.

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richms

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#465870 5-May-2011 18:04

Mains time is regulated to keep accurate time overall, even tho it may drift +/- a couple of mins during the day, it will always be caught up.

xtal oscilators may have mins per month errors as they dont use an accurate crystal in them since those cost actual money, vs a dirt cheap oscilator that you find in most dollarstore watches etc.

Could be a pretty lame turntable to use mains for the clock source. Quartz lock has been the norm since the 70s? My old first gen 1200 was certainly not using the mains power for anything since it was rock solid even running on a generator that was going all over the place freq wise.

Richard rich.ms

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