How to Convert 220v to 110v Without Transformer

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220V to 110V adapter without transformer?

Discussion in 'Electrical Engineering' started by peter, Jun 13, 2008.

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1. Most 220V to 110V travel adapter use a transformer, making it very heavy.
   Is there something that is transformerless? Perhaps some sort of switching
   circuit?

2. What do you want to power? There are lightweight "hi power" travel
   adapters - which just have a rectifier and a fuse inside. They are
   suitable for a lot of 110v kit, eg electric frypans, waffle makers, etc.

   If what you are powering is an external power supply, it is often
   lighter (and cheaper) to replace it with an 110v equivalent.

   One thing to consider is to travel with a 12v inverter, which can
   produce mains voltage from a car socket. You could add a lightweight 12v
   SMPSU to suit. Thus giving you a few hundred watts of the appropriate
   mains voltage, wherever you are.

3. 
   They're a triac light dimmer circuit with a fixed, they work only for
   resistive loads.

4. Unfortunately, that doesn't work. Usually it will result
   in some combination of smoke, sparks, and a bang;-)
   If you take 240V RMS and half-wave rectify it, you will
   end up with an RMS voltage of 240/sqrt(2) = 170V. This
   will run a 120V appliance at exactly twice it's power
   rating, and whilst overloading it in this way, also stress
   its insulation to twice its design voltage.

   To get the power rating right, you would need to half-wave
   rectify and then let only alternate pulses through by some
   other means. You still have the peak voltage problem, and
   a peak current which is 4 times the design rating.

   I built a switcher to solve this problem some years back.
   I use a pair of MOSFETs to switch the mains. What I do is
   switch off during the middle portion of each positive and
   negative going cycle. (IIRC, the switching angle is 43/137
   degrees to produce 120V RMS from a 240V RMS sine wave,
   but that's actually quite a bastard to work out with
   integral calculas, although going the other way is easy.)

   This has a number of benefits. The higher voltage part
   of the sine wave is removed, reducing the excess stress
   on the insulation of the 120V product (although it's still
   higher than when running on 120V RMS sine wave). It also
   keeps the instantaneous peak current as low as possible,
   although the power factor will only be 0.5. It also draws
   power only from the portion of the sine wave which is under-
   utilised by the very many power supplies which only draw
   current near the peaks, so although it generates a nasty
   harmonic current, it's cancelling out the nasty harmonic
   currents most other loads generate!

   In my case, this runs a 1050W 120V frying pan on 240V
   mains, and is a big improvement over the transformer which
   we used to lug around.

5. Erm, IME, it works rather well - I've got a US waffle iron in the
   kitchen that has run for well over 10 years on an adapter that consists
   solely of a power rectifier in a box (I opened the box to see what was
   inside, out of curiosity..).

   Of course I don't make waffles all that often

   I did modify things a little by running an earth wire to the metal case
   of the thing. As supplied, it was two pin.

   I'd replace it with a UK one, if I could find one that made such large
   waffles. It heats up quickly, too.

   Doubtless, in time, the thermostat contacts will burn out, or the
   element fail.

   Yep, I'm not disputing any of that. But all that is in this particular
   "hi power travel adapter" is a rectifier. I even checked its part number
   to make sure that is wasn't something special.

   I'd assumed that all these "hi power" adapters had the same arrangement.
   However, I have only opened this one to see.

6. 
   That is the current norm in modern switcher manufacturing practice.

   Also, I would add that most auto switch through that entire range just
   fine. In the past, one would have to set a switch depending on the
   region.

7. What travel appliance does not work on both 110 V and 220 V? I had a AA charger that says 110 to 240 V. It works perfectly in the USA.
   Last time I traveled to a 220V country, the charger overheated and the
   plastic shell started to warp. The batteries were damaged -- their plastic
   covers peeled off. Good thing I noticed it before it did more damage.
   Amazingly, it still worked when I bring it back to the USA.

   Even though it was out of warranty, I asked the manufacturer to replace it,
   and they did. Since then I am afraid to plug anything bought in USA into
   220V, even if it says 110-220V. Admittedly, that charger was not a very well
   known brand.

   This time I'm bringing a panasonic camera (usa version) to europe. The
   charger also says 110 to 220V. I suppose it should be safe to use, and I
   don't want to carry a 50W 220V to 110V transformer. But if there is a light
   weight device to step down 220V to 110V, I would feel safer using it. Maybe
   I can also bring my scary AA charger for other use...

   BTW, the high wattage voltage reducer all say "resistor network" in their
   product descriptions, but people responding to this thread say they use
   diodes, which make sense. Could it contain a diode and a resistor? Light
   dimmer (triac) also sounds feasible, but it would produce spikey waveform,
   probably not suitable for transformer use.

8. I use a Panasonic camera battery charger (supplied with the camera)
   regularly here on 235v. I've never had overheating problems - and it
   worked on 110v in the USA last summer.

9. 
   Modern stuff with switchmode power supplies is usually designed to cover
   the full range from 120 to 240V. This wasn't nearly as easy to do with
   magnetic transformers common in the past.

10. 
    Most modern switchers work from about 85V up to 265V. Most run easily
    down to 90V, and that is the goal since Japan uses 90 Volt system, AND
    the end of the line voltages can be lower than that.

11. 

    Guest

    | On Sat, 14 Jun 2008 21:25:40 GMT, James Sweet <>
    | wrote:
    |
    |>
    |>charles wrote:
    |>> In article <[email protected]>,
    |>>
    |>>> This time I'm bringing a panasonic camera (usa version) to europe. The
    |>>> charger also says 110 to 220V. I suppose it should be safe to use,
    |>>
    |>> I use a Panasonic camera battery charger (supplied with the camera)
    |>> regularly here on 235v. I've never had overheating problems - and it
    |>> worked on 110v in the USA last summer.
    |>>
    |>
    |>
    |>Modern stuff with switchmode power supplies is usually designed to cover
    |>the full range from 120 to 240V. This wasn't nearly as easy to do with
    |>magnetic transformers common in the past.
    |
    |
    | Most modern switchers work from about 85V up to 265V. Most run easily
    | down to 90V, and that is the goal since Japan uses 90 Volt system, AND
    | the end of the line voltages can be lower than that.

    Japan uses 100 volts. End if the line can be 90 volts.

12. ----------------------------
    I used a Sanyo automatic 120/240 VAC NiMH charger in the UK recently
    with no problems.
    Cheers,
    Roger

    I have used a Panasonic 120/240 NiMH battery charger on 240V (New
    Zealand ) with no problems.
    I took it to Italy as well.

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How to Convert 220v to 110v Without Transformer

Source: https://www.electronicspoint.com/forums/threads/220v-to-110v-adapter-without-transformer.169919/

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