I have just bought a door bell from the State however, I am staying in Singapore, where the voltage is 240 in oppose to 110. The vendor told me to simply get a 16-24VAC transformer with 40VA. After installation, the system worked only half a day and it stopped working and there seems to be a burning smell from the transformer. Did the vendor give me the right set of information?

Do I need a step down from 240v to 110v then use another transformer to transform it to the required 40VA?

Please advise as I am stuck and need to install the system asap.

My transformer has the following set of data: Input: AC220V 50 Mhz Output: AC24V 2A

  • \$\begingroup\$ you have a 24Vac doorbell and a 220/24Vac transformer 50Hz 48VA . Was there any center tap? Got a photo? Sounds ok from description. Did you measure Vout? \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Oct 14 '16 at 4:49
  • \$\begingroup\$ It sounds like you've got a 16 volt doorbell connected to 24 volts. What are the voltage, current and wattage specs for your "doorbell"? \$\endgroup\$ – FiddyOhm Oct 14 '16 at 9:57
  • \$\begingroup\$ Thanks for the advice. I am passing that info to my electrician. I bought a video doorbell and the only information I got was that I require a 16-24 VAC transformer...which I thought my electrician has installed for me. This is the website ring.com/pro \$\endgroup\$ – Jason Oct 17 '16 at 2:42

A 220 VAC transformer can work without any problem on 240 VAC. The difference in voltage is not enough to cause problems. A 110 V AC transformer will burn because the difference in voltage is to high.

I suppose that your transformer from the USA indicates 110 VAC/24VAC 2A or something like that.In that case you need a transformer as mentioned 240 VAC/24VAC 2A.

It might be that your transformer from the USA has to primary windings in parallel. In that case you could ask a technician to put both windings in series and you could use the transformer from the USA without any problem.

It is also possible to use a stepdown transformer as you indicated in your question. 240 VAC/110 VAC but with more than 50 VA because you have to compensate for the transformer losses.

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