View Full Version : Electronics: Should I get a transformer or look for another AC-DC adaptor?
04-13-2010, 01:01 AM
So here's the story, I bought a refurbished Roomba online, from a US retailer. Including shipping, I saved about $350 by doing so.
However, the US Roomba only comes with a 110V adaptor. As far as I can tell, it outputs 22.5 VDC 1.25A.
I'm wondering if I should source for a 240V adaptor which outputs the same voltage/current, or if I should get a step down transformer and plug the original adaptor into that instead.
Of course, getting a 240V adaptor would be neater (no bulky transformer!), but I'm worried that the difference in waveform/frequency/whathaveyou will break the Roomba. On the other hand, running a transformer 24/7 can't be good from the firehazard/electricity consumption.
04-13-2010, 05:38 AM
The adapter output is DC so waveform in doesn't matter to your electronics. Buy an adapter that goes from 220 VAC to 22.5 VDC 1.25A
04-13-2010, 05:54 AM
What Harmonious Discord said. But, if it turns out more convenient to get the step down transformer and plug the original into that, do that instead. Either will work just fine.
04-13-2010, 07:40 AM
a step down transformer can be used for other devices if ever needed.
unplug the transformer when not charging instead of the Roomba charger.
using a step down transformer won't leave you with a unused electrical device.
04-13-2010, 08:11 AM
Are you sure the adapter is really 110V only, or are you assuming that because it has a US-style input plug?
Many (not all) power step down adapters for electronics are not really "transformers" in the electronic engineering sense of the term. Internally they are what we call "switching power supplies". And many switching power supplies are designed to consume anything from about 110V to about 220V and either 50 or 60 Hz and still output the same desired output voltage, and if the output is AC, the same desired output frequency. This lets the manufacturer make just one power supply for worldwide sales and just alter the input connector to match the local configuration.
Look carefully at the info embossed on the Roomba's power adapter. It might say something like "Input 110-220V, 50-60Hz. Output 22.5VDC. Max current 1.25A".
If it does say that, then all you need is a simple male/female plug adapter to mate the Roomba adapter's connector to your local outlet style. Or just cut off the US-style connector and install your local style.
If it does specify 110V only, then as described by the others above, you're stuck getting a true off board transformer to change your mains power to 110V and plugging the Roomba charger into that. Or buying a generic power supply which consumes 220V and outputs 22.5V at 1.25A or better & swap the output plugs to get it to mate to the vacuum's input connector.
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