Step down or Step up Transformer

[SDR]

i want to get a cordless phone with an answer machine from USA. Is it better to get a Step Up Transformer from US or a Step Down Transformer here in UK please?

[Grunff]

The cordless phone base probably plugs into the mains via a low voltage adaptor. If this is the case, then the easiest and cheapest option is to buy a 240V -> whatever voltage it requires adaptor (from the UK).

[Harry Bloomfield]

SDR wrote on Tuesday (24/02/2004) :

Er.... Neither...

You would be better obtaining a small power supply of the correct output voltage + current and AC or DC as required by the unit. Probably this would be a 'wall wart' type.

Reason... The transformer in the existing PSU will have been designed for 60Hz and the UK uses 50Hz. It depends upon the design of the core, how well it might work on 50Hz.

[SDR]

Harry

Do you mean the type that can be picked up from say Argos for about a fiver with multiple adapter pins?

Will these be suitable for continuous use?

[Harry Bloomfield]

I was thinking of something a little better quality than the really cheap ones, perhaps a fixed output type....

What voltage/current AC/DC does the unit need?

[S Viemeister]

US cordless phones operate on different frequencies than UK ones. Unless you live very far away from anyone else, (an island of your own?) it may not be a very good idea. It may not even be legal.

[derek]

No that's not what's required.

Thirdly, they only change the pins. The voltage is the same . 240 volts will blow a 110v appliance.

Secondly, The mains here is 50 HZ as opposed to 60HZ in the USA 50 HZ may Blow, or overheat a 60 HZ transformer.

Firstly an American telephone is designed to work on the American telephone system. Which has different line voltage, and different signal levels. You may experience quiet transmission and/or quiet reception.

This makes it pointles to research innivotive solutions to 3, and 2.

DG

[Lurch]

I wouldn't bother with either. An American phone won't work on a UK phone line, totally different systems I'm afraid. ..

SJW A.C.S. Ltd.

[Nic O'Demus]

Absolute tosh.

At present and, errm, disregarding the legalities for the moment, I am currently using 4 USA cordless phones (without ansafone). Engenius, look it up on google or ebay. Brilliant phone and with an external aerial at about

12 m high is working well at 3 miles. 2.4ghz IIRC. With one handset I can answer calls on 4 incoming lines. A downside is that the base unit (12V) and battery/handset charger (9v) are separate units. So I have 4 base units and 4 charger units. 2 of these are operating from Maplins 240>120 transformers. Working fine but buzz a little. The others are working from 9 & 12v mains operated wall warts. As I say, my system works a treat. Connecting the base unit to the bt wall socket requires a US style (RJ11) plug to BT plug which is exactly the same as a modem cable in the uk.

In reply to the OPs' question, go for a UK wall wart of the correct voltage, wattage and polarity. HTH Nic.

[Lurch]

Hmm, I was reliably informed by quite a few people recently that they are different and don't work. If they do then I'll go back to my original plan.

Yep, go for that then if the phones work. Isn't anyone going to mention approvals for equipment connected to BT's network, no, I won't either then. ..

SJW A.C.S. Ltd.

[John Rumm]

Oh yes it is!

(Look at the DC voltage a current output of the current supply and get something with the same voltage and equal or greater current capability)

You are thinking of a plug "travel adaptor". A new wall wart PSU is self contained and will provide DC at whatever voltage it is supposed to...

A 240->120V step down transformer with the existing PSU will also work in all likelyhood.

If it is a linear PSU (i.e. not switched mode) then it is likely to run cooler - a transformer is an inductive load - its reactance will rise at a lower frequency and hence pass less current and so dissapate less power.

Not that different - the main differences we things like mark space ratios for pulse dialing - not that relevant these days (and anyway most BT exchanges handle US style pulse rates just fine)

[Dave Plowman]

You absolutely sure about that? Twas my understanding the nominal levels are identical.

[Nic O'Demus]

My little system works well for me. I suspect that there would be an anomaly with BTs' approval system and I will get round to reading all of it. Eventually. In short, yes a US cordless phone with or without an ansafone, will work perfectly well on the UK phone system. Buy a 240v wallwart to power it. A system phone, ie. pbx etc, will not work when plugged into a BT or any other socket except the one that is wired to the correct CPU. IIRC BT adopted US telephony technology about 20+ years ago but designed their own socketry in order to (a) preserve the antiquated and existing copper/aluminium cabling and (b) to preserve their own monopoly. Nic.

[SDR]

Nic

Does the 50Hz/60Hz become an issue? Also where did you get the Wall warts from? I assume that facilities such as call identifier may not work here?

[Andy Wade]

That's completely wr>> Firstly an American telephone is designed to work on the American

As other have said, the main issue is the radio system. Unless the product is CE marked under the RTTE directive its use will be illegal in Europe.

[derek]

What, zero level into 600 ohms??? You would say that. ;-)

AIUI the line voltage differs by the voltage of 1 accumulator (2 volts) I don't know about the sending/receiving levels. But my experience in the days when BT phones had no features but bootleg phones could have memories etc was that a bootleg phone I obtained on T'Court Road was so quiet nobody would use it.

DG

[Paul W]

What frequency does the cordless use ?

I think you'll find it's 900Mhz (that is the frequency used in the states that is "equivalent" to our 2.4GHz spread spectrum stuff), which is bang in the middle of our GSM waveband, so if you live near to anyone - you ain't gonna be popular !

Paul.

[Scott M]

No.

No way, Jose!

The US system seems far better than BTs limited Caller ID/1471 system as, for those who don't know, it sends an actual caller name down the line.

[Owain]

"SDR wrote | i want to get a cordless phone with an answer machine from USA.

Don't. The mains voltage is the least of your worries.

1. American (Bellcore) Caller ID is completely different and incompatible with British caller ID. Bellcore caller ID is used on some cable telephone lines however.

1. The flash button corresponds to Recall. However the American Flash is a much longer line break than a British Time Break Recall, so your Flash key will probably just disconnect your call rather than acting as recall.

2. An American phone will not be CE approved and must not be connected to the British telephone network - contravention of the Telecommunications Act - which probably won't worry many people unless you shove 240Vac mains down the phone wire and electrocute a linesman, in which case you could face a manslaughter charge.

1. And most seriously, an American cordless phone will not use British radio frequencies and as it won't be type approved to the relevant specification for use in the UK you are using an unlicensed radio transmitter in contravention of the Wireless Telegraphy Act 1949. It is an offence to use, IMPORT, manufacture, sell, advertise OR POSESS, without authorisation, non-approved cordless telephones. Use of such apparatus, particularly high power models that are available in some other countries, can cause harmful interference to other authorised radio users. It is also an offence to connect them to the public telephone system. Where necessary, the Radiocommunications Agency will prosecute or take other enforcement action under the Wireless Telegraphy Acts to prevent the harmful interference caused by those who use non-approved apparatus or possess such apparatus without authority to do so. Agency officials can seize apparatus found in unlawful use or possession and the courts can order its forfeiture. [from RA

193 (Rev 3) September 1999] see for updated URL if this one is out of date)

| Is it better to get a Step Up Transformer from US or a Step Down | Transformer here in UK please?

Step down in the UK - will be made to UK safety standards, and they're heavy to post/carry.

Owain

[MarkM]

Rubbish. We used an american cordless phone here for many years. IIRC, I had to replace the telephone line plug first, as well as getting a new wall wart power supply. This was in the old days when cordless phones here were expensive. Nowadays cordless phones here are very cheap, and pretty good, so theres no real point in getting one from the US.