Buying a wired video doorbell? Make sure you have the right transformer.

Of the many great deals coming up for Black Friday, a smart video doorbell is bound to be on sale. As someone who has one, let me tell you, it's pretty awesome. Seeing who is at the front door can be pretty handy, especially when you're not at home to peek out of the curtains and have a look. But the fun will be short-lived if you don't have an existing door chime transformer strong enough to power the thing.

Even if you already have a doorbell, your transformer might not provide enough power.

There's a good chance you have a chime transformer in your house already, especially if you currently have a doorbell. It's a small metal electrical device that converts your house voltage to the low-voltage a doorbell chime needs, and you wouldn't even know it was there unless you needed to replace it. Since most door chimes don't need much current, it's fairly common to find 8V or 16V / 15-20VA (volt-amps, a unit of power in an electrical circuit) transformers used for them, especially in homes more than 20 years old.

It's also the first thing you should look at if your new video doorbell doesn't "act right." Your current transformer could be enough for things to turn on and initially connect to Wi-Fi, but once you try to connect video or even send data through the app or your virtual assistant, things might get a little squirrely, and the whole works will lock up. Also, as your smart doorbell does more things, it needs more power, and a low-power transformer can't provide it.

Here's where we need to mention that you need to be safe. Finding and changing a door chime transformer isn't hard, but it is connected to your house's 110-volt power and can be potentially harmful. Unless you know what you're doing or have confidence you can do it yourself, call an electrician.

If you suspect your transformer isn't powerful enough, first, you need to find it. Look around the chime itself — the small box inside your house where you hear the bell — for a blank cover over an electrical box first, then open the cover of the chime itself or your electrical panel if you don't see anything there. Since one side of the transformer is connected to over 100 volts, it shouldn't be just laying around anywhere, but I have seen them mounted inside an electrical box in the attic or basement. You can also follow the wires connected to the chime, which will lead back to the transformer if all else fails.

If your door chime transformer is inside your electrical panel and isn't powerful enough, you should probably call an electrician and not attempt to change it out yourself.

Finding the transformer can be harder than changing it, but call an electrician unless you know what you're doing.

Once you find it, make sure the power is off and look at the top of the transformer itself. You'll find a sticker or some engraving that tells you the voltage and power in VA that it's rated for. You'll need a transformer rated at 16-24 VAC and 30 VA to power things properly. If that's not what you have, you need to change it.

These parts aren't hard to find, and as long as they are properly rated, every one of them will work. Amazon is a great place to pick one up. Just get one that mounts the same way your existing one does, and you'll be set up in no time.