Power supply for eufy doorbell


Old 12-28-19, 11:16 PM
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Power supply for eufy doorbell


the eufy doorbell requires a 16vac 30va, can i use a power supply adapter with 18vac 500mA to operate it? Will it damage the doorbell?
Also im just trying to understand current and power since i have no clue, 16vac 30va = 1.8A, while 500mA = .5A, how 18VaC supplies enough current to doorbell requires 1.8A?

Old 12-29-19, 02:11 AM
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First of all, I'd strongly advise against using an 18VAC transformer to power a doorbell designed to operate at 16VAC. You _might_ get away with it for awhile, but over time you risk burning it out--probably not immediately, but eventually.

The power ratings on transformers confuse a lot of DIYers. The Voltage rating tells what nominal voltage the transformer _delivers_ to a circuit; but the 30VA (30 Volt-Amps, or effectively, 30 Watts) is the _maximum_ power it _CAN_ deliver to a circuit, not the actual power it delivers in practice. Most devices, like doorbells, actually use less power in practice that what the transformer is rated for.

Likewise, your 18VAC transformer rated at 500mA means that it's rated to deliver a _maximum_ of 500mA at 18VAC. In practice, the amount of current it delivers is determined by the effective resistance of the circuit, which may be a lot less than 500mA.

However, using an 18VAC to power a circuit designed for 16VAC means that the higher voltage pushing more current (Amps) through the circuit than it--the circuit-- was designed for. You risk burning out the bell/chime/sounder as well as the transformer.

It looks like you can get a 16VAC 30VA transformer on eBay for about 21 or 22 $---you do the cost/risk analysis. ( I didn't do an extensive search for the best deal--you might find something for less. Transformers are pretty basic--if they work, then they work: Old used transformers are not significantly different from brand-new shiny transformers.)

EDIT: I goofed: I didn't look up "eufy doorbell" until after I'd posted. I would _definitely_ advise against using a differently rated transformer on a more elaborate electronic system like eufy, as opposed to a traditional chime-only doorbell.
Old 12-29-19, 10:38 AM
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That looks like a nest derivative.

Those units operate on a fairly broad power supply.
You can use anything from 16-24 vac.
The 30 watts is larger than most need but they all seem to claim they need that much power.
So they are saying the unit required almost 2A of power. That would rule out your plug in supply.

The depot carries a fairly cost effective transformer.

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