Home |
Search |
Today's Posts |
|
Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
#1
|
|||
|
|||
Foreign Travel voltage converter (1500Watts 220V to 120V)
Hi all fellow techs!!
I wonder what they put in those very small devices.It is certainly not a real power transformer. Low power devices (50W) contain an autotransformer.(I took one apart) I think it might be some kind of dimmer (good only for resistive loads). Has anyone taken one of those gadgets apart?? Many thanks for your feedback. Jacques |
#2
|
|||
|
|||
It is either a circuit very similar to a light dimmer, or possibly just a
rectifier. "Jacques Carrier" wrote in message om... Hi all fellow techs!! I wonder what they put in those very small devices.It is certainly not a real power transformer. Low power devices (50W) contain an autotransformer.(I took one apart) I think it might be some kind of dimmer (good only for resistive loads). Has anyone taken one of those gadgets apart?? Many thanks for your feedback. Jacques |
#3
|
|||
|
|||
"Michael A. Covington" writes:
It is either a circuit very similar to a light dimmer, or possibly just a rectifier. A rectifier would cut the power in half compared to 230 VAC for a constant resistive load. This is not what you want. --- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/ Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/ +Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm | Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html Note: These links are hopefully temporary until we can sort out the excessive traffic on Repairfaq.org. Important: Anything sent to the email address in the message header is ignored. To contact me, please use the feedback form on the S.E.R FAQ Web sites. |
#4
|
|||
|
|||
"Sam Goldwasser" wrote in message ... "Michael A. Covington" writes: It is either a circuit very similar to a light dimmer, or possibly just a rectifier. A rectifier would cut the power in half compared to 230 VAC for a constant resistive load. This is not what you want. I thought the high powered ones were nothing but diodes? They're only good for resistive loads, mostly they're made for irons and hair dryers. |
#5
|
|||
|
|||
"James Sweet" writes:
"Sam Goldwasser" wrote in message ... "Michael A. Covington" writes: It is either a circuit very similar to a light dimmer, or possibly just a rectifier. A rectifier would cut the power in half compared to 230 VAC for a constant resistive load. This is not what you want. I thought the high powered ones were nothing but diodes? They're only good for resistive loads, mostly they're made for irons and hair dryers. A diode would produce half wave rectified 230 V. This would cut the power in half compared to using raw 230 VAC but would still be twice the power expected by a 115 VAC resistive load. For example: 115 VAC 1.5 kW space heater. On 230 VAC: 6 kW. On half wave rectified 230 VAC: 3 kW. Either would result in failure very quickly. Or, did you have something else in mind? --- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/ Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/ +Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm | Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html Note: These links are hopefully temporary until we can sort out the excessive traffic on Repairfaq.org. Important: Anything sent to the email address in the message header is ignored. To contact me, please use the feedback form on the S.E.R FAQ Web sites. |
#6
|
|||
|
|||
"Sam Goldwasser" wrote in message ... "James Sweet" writes: "Sam Goldwasser" wrote in message ... "Michael A. Covington" writes: It is either a circuit very similar to a light dimmer, or possibly just a rectifier. A rectifier would cut the power in half compared to 230 VAC for a constant resistive load. This is not what you want. I thought the high powered ones were nothing but diodes? They're only good for resistive loads, mostly they're made for irons and hair dryers. A diode would produce half wave rectified 230 V. This would cut the power in half compared to using raw 230 VAC but would still be twice the power expected by a 115 VAC resistive load. For example: 115 VAC 1.5 kW space heater. On 230 VAC: 6 kW. On half wave rectified 230 VAC: 3 kW. Either would result in failure very quickly. Or, did you have something else in mind? I was thinking they had a chain of diodes and made use of the voltage drop, guess I could be wrong though. |
#7
|
|||
|
|||
In article DSQZc.1963$UR2.1628@trnddc08, James Sweet wrote:
I was thinking they had a chain of diodes and made use of the voltage drop, guess I could be wrong though. The "converters" are just a big resistor. They really have very little use except for things like hair dryers. Your best bet is to: 1. If it has a "wall wart" bring the 120v with you and get a replacment when you arrive. They are relatively cheap, and will fit the local outlets. It's a lot easier to get an exact replacement if you have the original in your hand. 2. Buy a transformer. Note that they are sold as xxx watt, but it's really xxx VA on a good day if the moon is in the right phase. Expect to use the transformer for half of it's rating. If you come to Jerusalem, I can give you the name of a transformer shop that will make what ever you want to specification. For example, most transformers don't carry the ground through, I had a 250va transformer (not auto transformer as most are) with the ground carried through and a grounded core made up for my grounded tip soldering iron. 3. Think multivoltage/multisystem, when you buy things. Make your next hair dryer a multivoltage one, etc. Buy in shops that specialize in serving the 220 volt community instead of "travel shops". Geoff. -- Geoffrey S. Mendelson, C.T.O. GW&T Ltd., Jerusalem Israel IL Voice: 972-544-608-069 IL Fax: 972-2-648-1443 U.S. Voice: 1-215-821-1838 |
#8
|
|||
|
|||
"James Sweet" writes:
"Sam Goldwasser" wrote in message ... "James Sweet" writes: "Sam Goldwasser" wrote in message ... "Michael A. Covington" writes: It is either a circuit very similar to a light dimmer, or possibly just a rectifier. A rectifier would cut the power in half compared to 230 VAC for a constant resistive load. This is not what you want. I thought the high powered ones were nothing but diodes? They're only good for resistive loads, mostly they're made for irons and hair dryers. A diode would produce half wave rectified 230 V. This would cut the power in half compared to using raw 230 VAC but would still be twice the power expected by a 115 VAC resistive load. For example: 115 VAC 1.5 kW space heater. On 230 VAC: 6 kW. On half wave rectified 230 VAC: 3 kW. Either would result in failure very quickly. Or, did you have something else in mind? I was thinking they had a chain of diodes and made use of the voltage drop, guess I could be wrong though. Let's see... Say 1.5 kW rating dropping from 230 VAC to 115 VAC. If half wave rectified, that means it has to drop the peak voltage by about 100 V (someone else can figure out exactly how much!) That means the adapter dissipates or otherwise gets rid of several hundred watts. There must be a mini-wormhole in there to dump the heat to another part of the Universe. --- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/ Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/ +Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm | Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html Note: These links are hopefully temporary until we can sort out the excessive traffic on Repairfaq.org. Important: Anything sent to the email address in the message header is ignored. To contact me, please use the feedback form on the S.E.R FAQ Web sites. |
#9
|
|||
|
|||
(Geoffrey S. Mendelson) writes:
In article DSQZc.1963$UR2.1628@trnddc08, James Sweet wrote: I was thinking they had a chain of diodes and made use of the voltage drop, guess I could be wrong though. The "converters" are just a big resistor. They really have very little use except for things like hair dryers. Not really. Think about what you just said for (1) variable load and (2) where the heat goes. --- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/ Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/ +Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm | Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html Note: These links are hopefully temporary until we can sort out the excessive traffic on Repairfaq.org. Important: Anything sent to the email address in the message header is ignored. To contact me, please use the feedback form on the S.E.R FAQ Web sites. |
#10
|
|||
|
|||
Sam Goldwasser wrote in message ...
"James Sweet" writes: "Sam Goldwasser" wrote in message ... "James Sweet" writes: "Sam Goldwasser" wrote in message ... "Michael A. Covington" writes: It is either a circuit very similar to a light dimmer, or possibly just a rectifier. A rectifier would cut the power in half compared to 230 VAC for a constant resistive load. This is not what you want. I thought the high powered ones were nothing but diodes? They're only good for resistive loads, mostly they're made for irons and hair dryers. A diode would produce half wave rectified 230 V. This would cut the power in half compared to using raw 230 VAC but would still be twice the power expected by a 115 VAC resistive load. For example: 115 VAC 1.5 kW space heater. On 230 VAC: 6 kW. On half wave rectified 230 VAC: 3 kW. Either would result in failure very quickly. Or, did you have something else in mind? I was thinking they had a chain of diodes and made use of the voltage drop, guess I could be wrong though. Let's see... Say 1.5 kW rating dropping from 230 VAC to 115 VAC. If half wave rectified, that means it has to drop the peak voltage by about 100 V (someone else can figure out exactly how much!) That means the adapter dissipates or otherwise gets rid of several hundred watts. There must be a mini-wormhole in there to dump the heat to another part of the Universe. --- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/ Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/ +Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm | Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html Note: These links are hopefully temporary until we can sort out the excessive traffic on Repairfaq.org. Important: Anything sent to the email address in the message header is ignored. To contact me, please use the feedback form on the S.E.R FAQ Web sites. Sam is right.Power must be eliminated!! I was thinking about a simple 220V SCR dimmer adjusted to fire around 45 degrees on each positive half cycle of the 220V line input.I guess that could give about the 1500W required by an hair dryer,a toaster,etc. which operate normally at 120V. I found one of those 1500W converters (very small) but I cannot crack it open to peek inside........They cost about $20 in Montreal. The 50W model costs only $5 .It is a simple autotransformer.(220V to 120V) Many thanks for the replies. Jacques |
#11
|
|||
|
|||
"Geoffrey S. Mendelson" wrote in message ... In article DSQZc.1963$UR2.1628@trnddc08, James Sweet wrote: I was thinking they had a chain of diodes and made use of the voltage drop, guess I could be wrong though. The "converters" are just a big resistor. They really have very little use except for things like hair dryers. They're most certainly not a resistor, a 1500W converter stepping 240 down to 120 would be dissipating a tremendous amount of power. |
#12
|
|||
|
|||
"Jacques Carrier" wrote in message om... .... | Sam is right.Power must be eliminated!! | | I was thinking about a simple 220V SCR dimmer adjusted to fire around 45 | degrees on each positive half cycle of the 220V line input.I guess that could | give about the 1500W required by an hair dryer,a toaster,etc. which operate | normally at 120V. | | I found one of those 1500W converters (very small) but I cannot crack it open | to peek inside........They cost about $20 in Montreal. | | The 50W model costs only $5 .It is a simple autotransformer.(220V to 120V) That's correct. And the high power units use a triac - basically a light dimmer preset to provide 1/4 power to a resistive load. The switchable ones combine these two. NM |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Why a 220v welder is as good as a 120v..listen up, I discovered this w/o electrocuting myself | Metalworking | |||
voltage regulator that drops out of circuit | Electronics | |||
Voltage on Phase Converter | Metalworking | |||
Phase converter balancing | Metalworking |