Bought a cheap 230V to 110V step down converter. It uses a MOSFET. Will it fry?

[fuzzybabybunny]

I have a gift for a friend in Australia and the item draws 40W @ 110V AC. It's meant to be always on (small little hydroponic grow kit with LED lights and water pump and touchscreen).

I bought a "50 - 1875 Watt" step down converter and opened it up. My device only uses 40W max so is this going to be a problem?

All it uses is a MOSFET to step down the voltage and a large heatsink that it's attached to. There's an adjustment dial to fine tune the output voltage.

I'm under the impression that MOSFETs generate a lot of heat. Will this unit fry itself if left on to draw 40W basically 365/7/24?

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[Mayne]

It shouldn't.

 

[Fir]

That's a TRIAC not a MOSFET.
It's sinked reasonably well.
However you probably want more than 40W on it.
Those converters are fine.
Until a spike hits them.

 

[Thebobo]

I'm confused by your wordage, it's probably me but you could always use two in parallel if your concerned about current draw.

But

• 2 Selectable Settings (50W or 1875W)
  • 1875W - Designed for heat-related appliances including hair dryers, irons, heating pads, etc. ( max. 1600 watts ). Do not use other electronics on the 1600W setting.
  • 50W - Designed for small electronics such as battery charger, cell phone charger, shavers, answering machines, portable radio, etc. ( max. 50 watts )
• Note: Travel converters are not designed for continuous use. Unplug it when not in use.

 

[fuzzybabybunny]

That's a TRIAC not a MOSFET.
It's sinked reasonably well.
However you probably want more than 40W on it.
Those converters are fine.
Until a spike hits them.

How come it needs more than 40W? What happens if the voltage is too low? There will be times when this hydroponic unit will be drawing way less than 40W. The lights turn off at night and the pumps turn off as well. Only thing that might be running is an internal clock and microcontroller.

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[Mayne]

why would you want the pumps turning off?

 

[PottedMeat]

oh wow that's awful.

that's a standard triac-diac dimmer circuit being used as a 'step down converter'??? it's even got a little trimmer lol. i'm assuming they have it set to fire at ~120 on the 220v cycle.

i'd imagine how this thing behaves is completely dependent on the load. resistive - fine. inductive - hell naw. smps... i dunno. the rectified waveform will be missing a lot and the input caps won't be fully charging . are there any youtube reviews under load?

the best option would be a legit step down transformer

 

[fuzzybabybunny]

oh wow that's awful.

that's a standard triac-diac dimmer circuit being used as a 'step down converter'??? it's even got a little trimmer lol. i'm assuming they have it set to fire at ~120 on the 220v cycle.

i'd imagine how this thing behaves is completely dependent on the load. resistive - fine. inductive - hell naw. smps... i dunno. the rectified waveform will be missing a lot and the input caps won't be fully charging . are there any youtube reviews under load?

the best option would be a legit step down transformer

Soooo... What would happen if I plugged in, say, a device that draws varying loads of 2W - 40W on this converter 24/7?

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[andy2000]

I wouldn't use one of those on anything other than a simple resistive load (like a hairdryer, toaster, or lamp). For anything electronic, or with a transformer, you really need a step down transformer. It's bigger, and more expensive, but not too big for only 40W. If the device has an external power adapter, it's probably easier to replace the power adapter.

 

[Red Squirrel]

I'd be curious to stick a scope on the end of that. I doubt it's a pure sine wave coming out the other end. Does look like it's a triac, rated for 25A, so technically will be fine for a 15a socket. https://www.st.com/resource/en/datasheet/t25.pdf

I don't think it would do well with any kind of motorized load though, but probably be fine for resistive loads and SMPS based loads like computers. I'd stick a scope on it though to see what the peak voltage is.

 

[fuzzybabybunny]

The device I have is this:

https://www.amazon.com/AeroGarden-Bounty-Gourmet-Herb-Seed/dp/B010NBJZLK

So it's got some lights and a pump, but also a microcontroller that runs the customizable timing of the pumps and lights and the LCD.

If I use this converter to step down voltage the unit won't run, right?

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[sdifox]

don't be cheap and buy one like this

https://www.amazon.ca/Simran-AC-100...locphy=9000783&hvtargid=pla-314667877869&th=1

pay a bit more and get the 500w one

https://www.amazon.ca/Simran-AC-100...locphy=9000783&hvtargid=pla-314667877869&th=1

 

[PottedMeat]

^the 100w one should work, the datasheet for the garden says ~54w

Soooo... What would happen if I plugged in, say, a device that draws varying loads of 2W - 40W on this converter 24/7?

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i wouldn't send without having actually tested it with that garden as the load. ...you could wire it up to a dryer socket to test it out.

it looks like real 100W step down transformers are $15-$30 on amazon

someones youtube review of a 500w similar type:

https://www.youtube.com/watch?v=NWivcxbg4hM

 

[Thebobo]

Just buy some led grow lights a timmer and pots etc. Not everything has to be wifi usb hi tec.

 

[nakedfrog]

Is the power supply actually integrated into the unit itself?

 

[fuzzybabybunny]

Is the power supply actually integrated into the unit itself?

Yes.

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[fuzzybabybunny]

Just buy some led grow lights a timmer and pots etc. Not everything has to be wifi usb hi tec.

I already bought the unit. It's a gift. I'm not going to give a DIY project as a gift.

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[fuzzybabybunny]

I'm going to have to buy the step down converter in Australia because I'm leaving in a few hours.

Would something like this work?

https://www.amazon.com.au/Step-Down-Voltage-Converter-Transformer-BESTEK-Protected/dp/B01LZ4SBAY/

It says not to use for hair dryers, coffee machine, etc. Why can't it do resistive loads?

Would a device with LEDs and water pump not work with this then?

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[PottedMeat]

It says not to use for hair dryers, coffee machine, etc. Why can't it do resistive loads?

it can, a hair dryer is 900+W, coffee maker is 1000+W

it will probably work alright. the best bet is a nice heavy transformer.

 

[fuzzybabybunny]

it can, a hair dryer is 900+W, coffee maker is 1000+W

it will probably work alright. the best bet is a nice heavy transformer.

It says "Please do NOT use this converter to supply power for your hair dryer, hair straightener or curling iron regardless of their wattage."

Regardless of wattage.

Any idea why they would say this?

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[sdifox]

I'm going to have to buy the step down converter in Australia because I'm leaving in a few hours.

Would something like this work?

https://www.amazon.com.au/Step-Down-Voltage-Converter-Transformer-BESTEK-Protected/dp/B01LZ4SBAY/

It says not to use for hair dryers, coffee machine, etc. Why can't it do resistive loads?

Would a device with LEDs and water pump not work with this then?

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why are you buying travel voltage converters?

 

[William Gaatjes]

Triacs, start conducting when a current is injected at the gate. But for the triac to remain conducting, either a lot of current needs to be injected in the gate all the time continuously (Or use a constant series of (high frequency, like 10kHz) short pulses during which the triac must remain conducting, this reduces the self dissiaption of the triac) when the current the triac is switching is lower than the required holding current or the current that flows through the triac must be higher than the holding current for the triac to remain conducting. In the latter situation, it will remain on indefinitely as long as the current flows. Now, AC current repeatedly drops to 0 so the triac needs to be fired every positive and negative half of the sine wave.

The short version is that a triac needs a minimum load current to function properly when having a simple gate drive circuit. That is why with simple dimmers , the triac needs a minimum load or it will starts turning off randomly and produce very nasty output voltage spikes.
That is where the 50W minimum for example comes form.

 

[PottedMeat]

Regardless of wattage.

Any idea why they would say this?

i can't think of a technical reason why. i'll guess they just don't want to deal with potential issues with a wide variety of products so they just say 'don't use it with these at all'
random googling says a curling iron is about ~180W, near device limits, but hair straighteners average ~80W, so not sure whats up with that

 

[Red Squirrel]

I could say the hair dryer, because it has a motor, but strictly resistive devices should be fine. Or do triacs rely on the fact that there is an inductive device to function properly? Maybe they don't like purely resistive devices either. If that's the case you could just throw a choke in series with the whole circuit though. Since it's 60hz I don't know if you need a choke with laminated plates, or if ferrite would do?

The best thing is to just try it, what's the worse that can happen.

Just don't leave anything like that unattended, and monitor the temperature of the triac.

 

[eng2d2]

I have a gift for a friend in Australia and the item draws 40W @ 110V AC. It's meant to be always on (small little hydroponic grow kit with LED lights and water pump and touchscreen).

I bought a "50 - 1875 Watt" step down converter and opened it up. My device only uses 40W max so is this going to be a problem?

All it uses is a MOSFET to step down the voltage and a large heatsink that it's attached to. There's an adjustment dial to fine tune the output voltage.

I'm under the impression that MOSFETs generate a lot of heat. Will this unit fry itself if left on to draw 40W basically 365/7/24?

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How much? I need one to send to switzerland