Step Down Travel Transformer Questions - Page 1
Forum section: electronics / general

author: edy
author_rank: Super Contributor
timestamp: October 18, 2016, 02:23:23 pm
content: Hi,I have a question about travel power adapters and in particular Europe (Germany, France, Italy) and Israel, and using Canadian/US appliances. I have several 2-prong US/Canada adapters to charge phone, rechargeable batteries or with USB 5V plug on it. I believe they all have INPUT 100V-240V written on them, and it says 0.1A (100V) - 0.06A (240V) AC 50/60Hz.My understanding is if it accepts input 100-240V, then it should be ok simply to use a converter PLUG and that's all, something like this:Now, I know people who are in Europe have type E/F and the pins are slightly thicker than the Israeli type H plugs, but apparently Israel has been changing over to some kind of plug that is more universal. Either way, the plug adapter above has slightly thinner pins.... Will these adapters fall out of the wall? Are they too loose for Israel/Europe? I don't want to get the thicker ones for Germany/France and have to force them into the Israel plug or have problems removing them.... But if Israel is using newer Euro-friendly outlets, will the thinner pronged adapter fall out?Now regarding any appliances that DO NOT have the 110-240V written on them, I purchased one of these step-down transformers from 240 V to 120 V, rated at 50 W:The other end accepts a regular Canadian/US 2-prong plug, so I can plug in any other gear that doesn't have the transformer built in and only takes 120V. What if I plug in a charger that accepts 110-240V into the step-down transformer... will it have any issues? It will just be thinking it is plugged into a US/Canada outlet, right? So is it safer just to use the step-down adapter for ALL my appliances, just in case?Another question is the fact that everything seems to be 2-prong. None of my appliances seems to care about the grounding. Will I have any issues? Do the plugs in Europe/Israel have some kind of protection that needs a ground-pin pushed into the socket to allow current on the live pins? For example, I heard someone say they went to a hotel and they told them to stick a PEN into the ground pin (I guess to flip a trap door there) which tricked the outlet into supplying power on the live pins.Any help would be appreciated! Particularly with Europe/Israel compatibility and the thinner plug, and this whole thing about grounding plugs and whether it is common. Thanks!

author: madires
author_rank: Super Contributor
timestamp: October 18, 2016, 02:53:21 pm
content: When your device or wall wart is rated for 240V/50Hz, it should be fine. Most SMPSUs are. The adapters in the picture are meant for low power devices (IIRC, max. 2A). For more power or a tighter fit you would need a Schuko adapter (https://www.amazon.de/Hama-Reisestecker-USA-Typ-b/dp/B00NBLSLXS/), which also includes earth/PE. The step down transformer is a crude device based on a SCR or Triac and is only suitable for some stuff. Better get a real transformer. AFAIK, just the UK got sockets with shutters operated by the PE pin, but they got a different plug anyway. Can't tell you anything about sockets/plugs in Israel.

author: Zbig
author_rank: Frequent Contributor
timestamp: October 18, 2016, 03:06:41 pm
content: Quote from: madires on October 18, 2016, 02:53:21 pmHave you actually looked at the picture of the black/brown thing edy posted?It is a bare transformer with its core showing on the outside and just some plastic caps covering the terminals. Those are autotransformers and have some pretty interesting failure mode. My colleague has brought one (EDIT: not this exact type) that has blown its winding (due to an overload) and passed the input (240V) straight to the output

author: edy
author_rank: Super Contributor
timestamp: October 18, 2016, 03:57:36 pm
content: Yes... those autotransformers are exactly what I have used in the past, and why I'm asking these questions. Usually it was for some cheaper shaver that came with only 2-prong North American plug and didn't have a 110-240V range, just the 120V. It would buzz just a bit slower.My understanding is that the transformer will simply convert a 220-240V/50Hz input into a 110-120V output and presumably still at 50 Hz? Will that be tolerated by most appliances that will only accept 110V/60Hz? Like a shaver that normally operates on a 60Hz AC would be at 50Hz but still at the lower voltage, so it doesn't blow it. I assume some devices may not like the slower cycle, whereas others have no issues running at 50Hz vs. 60Hz?However most of the devices I used today have chargers/wall-warts that say Input AC100-250V 50/60Hz on them, and output is usually 2 A or less. They are typically used to output 5V to charge USB devices (like phone, Kindle, camera battery, smart watch, etc). And most of them are 2-prong only.So technically I may not need the transformers at all... only the simple physical pin-adapter from 2-flat US/Canada prong to the 2-round Euro/Israel plug?

author: Zbig
author_rank: Frequent Contributor
timestamp: October 18, 2016, 04:11:53 pm
content: Yes, the transformer won't affect the frequency - you'll still get 50 Hz. It's hard to say with confidence that each and every device you encounter will be fine with that but I couldn't think of many that won't from the top of my head. Pure resistive heaters definitely wouldn't care but on the other hand, those are the last type of devices you'd like to power from a tiny transformer. One device that would definitely not work properly would be a very old school, crystall-less radio clock that uses mains frequency as its time base. I don't suppose you are that attached to any of theseOne problem I could imagine would be a device using a transformer and a linear regulator with marginally low filter caps, but I'm just musing here now. Or a device using capacitive dropper. It'd be better if you just listed the devices you're going to use during the trip and we'd try to figure out whether they sould be fine or not.EDIT:I got one! Old-school, electromagnet-based electric shaver would run slowerYou'd only get 83% of your original shaving performance

author: madires
author_rank: Super Contributor
timestamp: October 18, 2016, 04:30:22 pm
content: Quote from: Zbig on October 18, 2016, 03:06:41 pmOk, I see. At first glance it looked like electrical tape

author: edy
author_rank: Super Contributor
timestamp: October 18, 2016, 04:37:51 pm
content: I plan on using several Blackberry chargers and some that are for USB charging. Some have a direct micro-USB cord attached, and others have a regular USB outlet and you use your own USB cable. They all seem to say 100-240V 50/60Hz on them. They range from about 1000 mA to 2100 mA.I will use them to charge a Phone, Kindle, backup-battery powerbank. The chargers look like these (one is Playbook rated at 2.1A, and the other which has a USB 5V is rated at 1A):I've also got something that looks like this... a bit cheaper quality but hopefully still ok:I guess as long as I draw about 2A (some will do 2.1 A so hopefully that is not overloading the adapter) then I am safe to simply use the small black adapter (the first picture I showed)?I also have one of these Blackberry micro USB chargers where the plug end can be changed from US/Canada to European (there are 2 plugs provided which clips in and out):Since most of my devices accept the micro USB anyways, I can use that to charge the Kindle, phone or powerbanks as needed and it is built for European plug. Hopefully it will fit into the Israeli outlet.As far as shaving, brushing, etc.... I am planning to use old-fashion blades and regular brush. One thing I know is a definite NO-NO is to make sure my wife does NOT take her hair-dryer with her. Usually she doesn't because most hotels have them anyways. They usually draw much higher wattage, so would melt the little black power adapter above. Same goes for the autotransformer (which I am thinking more and more that I probably don't need... since all my charger adapters seem to accept 100-240V 50/60Hz - and it's only 50 W rated anyways).Would it be advisable to plug the auto-transformer in the wall, then plug in my North American chargers that are say higher than 2A rated (even if they can accept 110-240V 50/60Hz) simply to make sure I don't melt the smaller black plug adapter? Then I'm using the autotransformer in a sense as a beefier adapter from the 2-prong round plug to the 2-prong flat plug and it just so happens to also step down the voltage. I know it provides no extra protection and stepping down the voltage won't be needed, but physically it will still let me connect to the Euro plug and if my device/charger is say able to output 3 A at 5V, then it is using 15 Watts and if you are saying the simple black adapter will not handle more than 2 A (or 2.1 A), then the autotransformer will tolerate it fine?If I can, I will just use the adapters that have the 100-240V input range that are 2.1 A or below, with the simpler black plug adapters. By the way, just because it says 2.1 A rated doesn't mean the device it is plugged into is drawing that current, right? For example, using the 2.1 A 5V Playbook charger on my Kindle, it will not be anywhere close to 2.1 A as the Kindle needs very little current to charge. Even the powerbank charger has 2 USB ports and is rated 2.1 A, but each powerbank itself has input max 1000 mA 5V only, so technically the charger shouldn't ever draw more than 2 A, even with both powerbanks plugged in. And in the case of charging one powerbank, a single USB is being used on the adapter so it should only be drawing 1000 mA max because the powerbank can't be fast-charged, it will limit itself to 1000 mA no matter what.

author: edy
author_rank: Super Contributor
timestamp: October 18, 2016, 06:04:00 pm
content: JUST AS AN ASIDE:I'm a bit confused as to how an autotransformer works with the 1 winding connecting both sides of the circuit.I think I understand better the 2 windings (separated electrically) around a single magnetically conductive core (like iron). The number of turns ratio between the input/output windings sets up the ratio of the input/output voltage, since input coil sets up an electromagnet field in the core, and then the output coil gets electromotive force induced in it by the electromagnetism.I think I also understand voltage dividers and central-tapping transformers to create a "ground" reference at the mid-point, which then lets you get +V and -V rails. Somehow looking at the autotransformer schematic eludes my thinking at the moment, since it is not electrically isolated one side from the other. You are just tapping on at a point that gives a smaller number of coils windings....Please tell me if I understand this correctly.I imagine an autotransformer or coil wrapped around an iron bar plugged into the mains. Say it is 50 Hz at 240 V for example. Let's say the coil has little to no resistance, it is ideal. There is an electromagnetic field building up one way, breaking down, then building up the other way, breaking down, etc... at 50 Hz for a full cycle. Since the mains current is so much stronger than the coil electromagnetic induction, the fact that there is a magnetic field being generated does little to slow down the current (like an inductor) so the phase of the current in the coil is practically the same as the mains (although I would imagine that it may have a "kick-back" since the magnetic field will want to resist change and keep the current steady even though the mains current is already changing direction).Anyways, if I tap 2 wires on to the coil that are practically next to each other, I will have no potential difference between them. It may as well be 1 wire split in 2. If I plug it in to something (as long as that thing doesn't get grounded) it will just sit there and do nothing. However, if I ground that single tap it will shock to the ground I assume because it will find another low resistance path back to the mains neutral.Now as I move the 2 wires tapping on to the coil further apart... a current will form in the other loop circuit (secondary loop) because of the electromagnetic field in the core. The other loop as long as it never gets grounded, will have current flow through it. Even though they are electrically connected directly by the conductor. It is almost like 2 geared wheels next to each other. As one wheel turns, the other wheel turns the opposite direction and the gears keep them locked in step. So the mains loop drives the secondary loop in proportion to the percentage of the coil turns it shares. If it shared 100% of the coil windings, it would feel the full voltage. If it shared 1 winding only of a 100 winding coil, the secondary loop would only feel 1/100th of the electromagnetic field in the core and only 1/100th of the voltage would be driving the secondary loop?Am I totally confused or on the right path here?

author: riyadh144
author_rank: Unknown
timestamp: October 18, 2016, 07:00:10 pm
content: I am from that area, and you will be just fine, no need for anything else.

author: bigsky
author_rank: Regular Contributor
timestamp: October 18, 2016, 09:52:28 pm
content: edy,(1) This Wikipedia article may be of interest:https://en.wikipedia.org/wiki/AC_power_plugs_and_sockets(2) The transformer you pictured looks problematic as I think most European sockets are recessed and I can't see how it would fit in. Also it looks like the laminations are exposed in the middle and they will not be earthed.(3) Just a note of caution that there are quite a few Chinese-made socket converters which are lethal, typically because the output socket is designed to accept many different plugs and the insulation is lacking. Remember that 240V is more dangerous than 110V.(4) If you are travelling to Europe (don't know about Israel) I would recommend buying any adaptors at your destination. From your posts it sounds like you are not that familiar with mains electricity and this will be safer for you. European product safety laws are quite strict and a reputable local shop is unlikely to sell something dangerous as they could be prosecuted.

author: bigsky
author_rank: Regular Contributor
timestamp: October 18, 2016, 09:59:43 pm
content: Here's a 240-120 autotransformer with earthed input and output, and a European schuko plug. This is a good-quality make - they use British-made toroidal autotransformers.http://www.ebay.com/itm/Tacima-SC-5422-100W-USA-to-EUROPE-Voltage-Converter-AUTOTRANSFORMER-110-120-/201658571380I have a few of these in various ratings that I need to sell (they have UK plugs on the input, though), but shipping to Canada may be prohibitive.

author: edy
author_rank: Super Contributor
timestamp: October 18, 2016, 10:46:10 pm
content: I shouldn't have a problem with the recessed plug as first stop is Israel and they have one of the most poorly designed Type H plugs ever when it comes to safety:http://www.worldstandards.eu/electricity/plugs-and-sockets/h/It seems to be compatible with European plugs now but the prongs are slightly thinner, so the first 2-prong adapter I showed has slimmer prongs that should fit without any issues. No grounding. Here is an example:http://www.international-electrical-supplies.com/israel-plug-adapter-wa-14-1-6-p1534.htmlHere a user posted an Israeli socket that should take both Israeli and Euro:Here is an example similar to my black version showed in my initial post:http://internationalconfig.com/icc6.asp?item=30300So most of my "wall-wart" type chargers for phone, Kindle, etc... use 2-prong non-polarized, and have 100-240V 50/60 Hz written on them, and are under around 2 A should be able to just plug in the wall with the simpler adapter that just physically mates up the US plug to the Israeli round plug.I'm thinking I should return the step-down autotransformers based what I'm hearing, unless there is some good reason to keep them. Also, on this Amazon review check out the negative reviews about people's transformer melting, blowing up, catching fire, heating up, only able to use for 10 minutes or a couple times before catastrophe's.... it's scary. How representative is that? :https://www.amazon.ca/Voltage-Converter-Travel-Power-Transformer/dp/B000VUCKOIHere are the reviews:https://www.amazon.com/product-reviews/B000VUCKOI/ref=cm_cr_dp_syn_footer?k=New%20220V%20to%20110V%20Step%20Down%20Voltage%20Converter%2050W%20Travel%20Power%20Transformer&showViewpoints=1From the reviews on page 6, here's a user who tried one in Israel and this is what happened shortly after:

author: bigsky
author_rank: Regular Contributor
timestamp: October 19, 2016, 05:29:49 pm
content: edy, I am also aware of horror stories about Chinese-made autotransformers, as I said, the style you pictured looks lethal.Also, (1) the three pin Israeli adaptor you pictured (labelled WA-14) looks dubious as the socket pictured is clearly designed to take a plug with a round body and I can't see how the two will engage properly, (2) the three pin Israeli plug you labelled "euro" is not a European plug - please read the articles carefully.Remember if you insert a US plug (eg on one of your dual voltage chargers) into a 240v socket using a simple adaptor, you will have 240v on the flat pins which are not that well insulated.

author: madires
author_rank: Super Contributor
timestamp: October 19, 2016, 06:26:52 pm
content: The plug with the three round pins doesn't match any common plug or socket used in the EU, maybe the Danish 107-2-D1. Please seehttps://en.wikipedia.org/wiki/AC_power_plugs_and_sockets#CEE_7_standardsfor the common types.

author: edy
author_rank: Super Contributor
timestamp: October 20, 2016, 04:09:40 pm
content: Ok, I returned the 220-110V AUTOTRANSFORMERS 50W that look like this:... And I bought one of these instead:http://www.pyleaudio.com/sku/PVKT130https://www.amazon.ca/PVKT130-100-watt-110-240V-Converter-Transformer/dp/B00EEJZPJOIt is fused and has a switch on the front to allow either 50W or 1600W. I am certain this is a safer choice, more idiot-proof and less likely to cause fires or burn equipment plugged into it.I was wondering, why is there a 50 W and 1600 W choice? Why not just keep it on 1600 W all the time, and then you can plug in BOTH less and more-wattage using appliances? Then you don't have to worry about forgetting to flip the switch from 50 W to 1600 W, if you by mistake plug your hair dryer in and it's still on 50 W?One other question is, can I still use this PYLE travel adapter and plug in the BlackBerry chargers (or others) that accept 110-240V, 50/60 Hz? It would act like a sort of "extra protection" just in case the charger is faulty at the higher voltage. The only thing is, I think the PYLE would be outputting 110V at 50Hz instead of 60Hz.

author: madires
author_rank: Super Contributor
timestamp: October 20, 2016, 04:21:29 pm
content: I think the 50W setting is a real transformer and the 1600W setting apparently a SCR/Triac based dimmer.