Recommendations for: Step-up Voltage Converter 110v to 220v

[lilliputian]

Hello all, first post on the forum!

A friend of mind acquired a Soviet-era lamp from Ukraine she'd like to use here in the US. It is a fiber optic lamp and a disc is supposed to rotate inside when turned on changing the colors, but of course when you plug it into 110v (with a 2-prong to US adapter) it is naturally very dim and the motor doesn't turn. While it may be that the lamp needs other work besides, the first step is to get it the proper voltage that it was designed for.

There are a number of questionable 5-letter-brand step-up converters on Amazon, but I figured I would ask the experts to see if anybody has any recommendations. Not looking to spend lab-quality money, preferably <$50 yankee bucks, and preferably something on the small side that she can stick under the bureau where the lamp will reside.

Thanks in advance for the help. Attached are pictures of the lamp itself (cute, right?)

-Lilliputian

PS. I am savvy to fixing old computers and such (ie. replacing components same-for-same), but wouldn't feel comfortable modding the lamp, as I don't have the expertise to find the correct power transformer, modify the other components, etc.

[themadhippy]

Double check the lamp ,but it looks like you dont need a110-220v transformer,but a 110v to 12v transformer to replace the one already in there

[lilliputian]

Yes, the motor is 12V, but the power transformer in the lamp is expecting 220, no?

[Benta]

Yes, the motor is 12V, but the power transformer in the lamp is expecting 220, no?

Both lamp and motor are 12 VAC. Replace the transformer, then it should work. It seems to be in the 15 VA range, but finding an exact is likely not possible. A 15 VA toroidal type mounted vertically would fit, but you'll need to create some mounting hardware.

[themadhippy]

Yes, the motor is 12V, but the power transformer in the lamp is expecting 220, no?

the lamp looks like its also 12v,so why go up to 220v to drop down  to 12v?

[lilliputian]

As mentioned in my initial post, I'm not really comfortable trying to find a suitable replacement transformer for the lamp itself, that's really outside of my expertise.

[Benta]

As mentioned in my initial post, I'm not really comfortable trying to find a suitable replacement transformer for the lamp itself, that's really outside of my expertise.

In that case, remove the transformer and connect a 12 VAC, ~1 A wall-wart instead.

[themadhippy]

As mentioned in my initial post, I'm not really comfortable trying to find a suitable replacement transformer for the lamp itself, that's really outside of my expertise.

how did you intend to work out the size of step up transformer you required? its exactly the same method to calculate a step down transformer.You know the required voltage and current ,in this case the lamp needs 8W and the motor 1W so a total of 9 watts at 12V,or 0.75A,add a bit for luck ,call  it 1A.Transformers are normally rated in VA so in this case you want something rated for at least  12V 12VA.

[lilliputian]

I'm talking about a standalone voltage converter that she can just plug it into between the lamp and the wall.

[BeBuLamar]

It's better to replace the 220V to 12V transformer with a 110V to 12V transformer. It's more difficult to find a step up transformer from 110V to 220V.

[tunk]

Maybe something like these:
https://www.amazon.com/s?k=step+up+110+to+220+voltage+converter&rh=p_36%3A-2000&crid=2EY4S47J2YO9H&qid=1715344306&rnid=386442011&sprefix=step+up+110%2Caps%2C201&ref=sr_nr_p_36_5

[mariush]

A 12v AC wallwart adapter would be easiest choice.  Just add a barrel jack connector besides the power cable and plug the wallwart in the barrel jack connector.

It's minimal intrusion, literally just cutting a round hole for the connector or the barrel jack cable.

example 12v 10w AC adapter : https://www.digikey.com/en/products/detail/ideal-power-ltd/77DA-12-12/15667495

2.1mm / 5.5mm standard barrel jacks : https://www.digikey.com/short/2dh4nchm  or cables with female jacks : https://www.digikey.com/short/w13whj01  - get a cable with barrel jack with a thread so that you can screw/lock to lamp case, and solder the wires to the output of the AC transformer and just not plug the lamp in the mains using the regular cable. 

other option...

Get a 110v AC : 220v AC transformer and put it in a wood or plastic box, with AC sockets on the box.

Example : https://www.digikey.com/en/products/detail/hammond-manufacturing/1182D240/4809289  117v/230v in , 240v out  connect the two primary windings in parallel to set to 117v AC input.

It's Size / Dimension 76.20mm Dia  , Height - Seated (Max) 31.75mm  so you'll need a box at least 80mm square, at least 35mm tall

Here's an example : https://www.digikey.com/en/products/detail/bud-industries/PN-1331-DG/439758  or

it will cost more, but the AC transformer can be reused with other things.

[xvr]

I'm talking about a standalone voltage converter that she can just plug it into between the lamp and the wall.

Standalone voltage converter, with output suitable for transformer, is a transformer itself. So there is no reason to turn 2 transformer in series - just one transformer will be enough.

[langwadt]

https://www.walmart.com/ip/STEP-UP-CONVERTER-110V-to-220V-50W-TRANSFORMER-VOLTAGE-PLUG-FOREIGN-IN-USA-NEW/101268110 ?

[Zero999]

https://www.walmart.com/ip/STEP-UP-CONVERTER-110V-to-220V-50W-TRANSFORMER-VOLTAGE-PLUG-FOREIGN-IN-USA-NEW/101268110 ?

Assembled Product Weight
0.5 lb

It's a pile of 💩. It's imposible to squeeze a 50VA autotransformer in something that size. It's obviously fake.

The 1 star rating and bad reviews say it all.

[BrokenYugo]

You don't really see much in the way of legitimate products in that realm, mostly generic black box stuff from China with very questionable insulation and assembly quality. Not the kind of thing you give a friend to leave plugged in.

This is about the most legit looking one I could find, and it looks a little sketchy to me, just not as sketchy as most of them. Again, not something I'd leave plugged in. https://www.amazon.com/Converter-Wireless-Charging-LX-500C-Appliances/dp/B078H3KG7Z/ref=pd_rhf_cr_s_pd_sbs_rvi_d_sccl_2_4/130-2557915-9950005?pd_rd_w=7lTKI&content-id=amzn1.sym.9c71db11-3b2f-49a1-9fef-afd524b20130&pf_rd_p=9c71db11-3b2f-49a1-9fef-afd524b20130&pf_rd_r=5BHWXQTYAPBA6YPX5BHK&pd_rd_wg=LwFX4&pd_rd_r=11e69f52-2732-42d0-9c70-a2749230b534&pd_rd_i=B078GYZC2D&th=1

It really is easier, safer, and more power efficient to change the transformer or convert it to an external 12V AC supply, if you can handle not mixing up two pairs of wires and use a screwdriver you're overqualified.

[CaptDon]

An external wall-wart type transformer should be at least 1A at 12V.A.C., The bulb is 10 watts@12v. A one amp wall wart will be just barely enough.

[Zero999]

I'd say a 1A wall wart is more than enough.

The bulb is 8W and the motor 1W, that's 9W. It's true, the motor will have a power factor under 1, but it won't be that bad. Suppose it's 0.5, which gives 2VA for the motor and 8W for the bulb, which is a total of 10VA, which is 833mA and still less than an amp.

I would also consider replacing the bulb with an MR16 LED lamp. The only issue might be ventilation, although someone at work did that with a fibre optic Christmas tree, with good results.

[lilliputian]

You don't really see much in the way of legitimate products in that realm, mostly generic black box stuff from China with very questionable insulation and assembly quality. Not the kind of thing you give a friend to leave plugged in.

...

It really is easier, safer, and more power efficient to change the transformer or convert it to an external 12V AC supply, if you can handle not mixing up two pairs of wires and use a screwdriver you're overqualified.

That's a shame, I thought maybe they were just rip-offs of something more reliable, but what you're suggesting is that all of them (apart from actual lab equipment) are probably a bit questionable. I definitely don't want to get one and give my friend a fire risk waiting to happen just for a lamp.

So if we take the previous suggestion for a replacement internal transformer (I think my friend enjoys the foreign power plug, so that would probably be preferred over an external transformer), I should be looking for a 12VA 1A transformer (with of course 110V input rather than the original 220)? I know a lot about at this point about replacing old capacitors and such, but transformers are new territory for me.

[lilliputian]

I would also consider replacing the bulb with an MR16 LED lamp. The only issue might be ventilation, although someone at work did that with a fibre optic Christmas tree, with good results.

If the current bulb is still too dim following transformer surgery (or if it burns out), will definitely take your advice.

[CaptDon]

I had to look again at your picture and indeed it is an 8W bulb. I had a nearly identical flower display that I parted out because the sun had damaged the plastic parts (It had been in a window for years) and mine was already wall wart powered and had a 10W 12V lamp that looks exactly like the 8W in the picture. They run hot!! My wall wart was hard wired from the factory and the flower base had a switch on it.

[lilliputian]

Sounds like yours had a good life.

[Zero999]

I would also consider replacing the bulb with an MR16 LED lamp. The only issue might be ventilation, although someone at work did that with a fibre optic Christmas tree, with good results.

If the current bulb is still too dim following transformer surgery (or if it burns out), will definitely take your advice.

I strongly recommend LED. I have some 4.8W LEDs, which produce 345 Lumens, which is equivalent to a 35W halogen and will be over four times as bright as your old 8W halogen, as well as using less power. Heck, you could even use a smaller transformer, which might even work out cheaper, even though the LED is more expensive. You can also use a lower power LED: 1W will probably be more than brighter than your halogen.