There was a time not long ago when, if you wanted to protect your home with an alarm system, you’d need to call an established company and have a technician come out and install sensors all over the house. You’d have to pay for the installation, and you'd also get saddled with high monthly monitoring fees.

Thanks to new technologies and the power of the Internet to connect our homes to our phones and other devices, it's now possible to install your own home security system quickly, easily and affordably. Some DIY home alarm systems don't even require monitoring service —. you can watch over things right from your smartphone — so you'll save a bundle every month.

Here are three smart bets for alarm systems you can install yourself to keep your home safe and sound.

Related: How to Secure Your Home Against Burglars

SimpliSafe

This whole-home alarm system is a breeze to install, as I recently discovered when I put it in my home. After ordering the number of window, door and motion sensing units I needed to cover my home, I was able to install them around the house in about an hour using the included 3M Command Adhesive strips. For doors and windows, one sensor goes on the window or door and the other on the frame. The motion sensors go wherever you need broad coverage — they sense movement up to 30 feet away in a 90-degree arc. The sensors then all connect automatically to a tower unit you place in a central location. I found the process super smooth.

Once the system is set up you can choose to have SimpliSafe monitor the sensors for you and alert the police if there's an alarm (after they contact you), or you can go with unmonitored service and just have alerts sent to your cell phone. I am using the monitored service. A few times I accidentally tripped the alarm and found the company's response time to be quite good. However, while I was away on vacation a few weeks ago, the company called to tell me that a motion sensor had been tripped. I asked that the police be sent and, after their investigation, I was told that nothing amiss was found. Apparently, it had been a false alarm. Aside from that one-time malfunction, the system has been working fine.

Speaking of malfunctions, the central tower to which all the sensors connect uses a cell-phone signal to communicate and it has a backup battery, so even if there's a power outage that knocks out the electricity and WiFi, it can still do its job. The tower also acts like an in-home alarm that screeches when a sensor is tripped.

In addition to keeping your home safe from intruders, you can also purchase additional sensors that alert you to flooding, carbon monoxide build-ups, smoke or fire and freezing temperatures.

Related: Carbon Monoxide Poisoning: Is Your Family Protected?

SimpliSafe equipment packages range for $230 to $540, or you can build your own system by purchasing the sensors a la carte. Monitoring plans range from $14.99 to $24.99 per month, but they are not necessary to use the system with a smartphone only.

Dropcam Pro

If you want an even easier way to keep an eye on things while you're away from home, you might consider putting a Dropcam somewhere inside. These standalone cameras have a 130-degree field of vision. They can zoom up to eight times in magnification and can see in the dark thanks to night vision. They stream what they're seeing right to your smartphone once you have the app installed.

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All you need to do to install the camera is plug it in and launch the app on your phone to get connected. You can then watch anything your camera sees through the app 24/7 for free. You can also set up the system to send you notifications when movement or sound is detected. And you can use the camera as a two-way communicator with anyone in the house; just talk through your app and your voice will come out of the camera.

For a monthly fee you can activate Dropcam's cloud recording service. This will store either the last seven or 30 days of video in the cloud soyou can review the footage at your leisure. Another benefit of signing up for the recording plan is that you can set your camera to detect specific areas of movement. Put a DropCam in your kitchen, for example, and you can set it to tell you if there's movement at the refrigerator or in the hallway.

Dropcam cameras run $199 and it costs $9.99 per month for the 7-day cloud recording plan and $29.99 per month for the 30-day option. Professional and consumer reviews for the system have been overwhelmingly positive. If there is a negative, it's that $199 can be considered costly for one camera, and the option to record your video adds even more cost.

iSmart Alarm

The iSmart Alarm system was one of the first DIY home security systems and it's also one of the most affordable, with gear packages starting at $199. In many ways, it combines the best features of SimpliSafe with that of Dropcam.

The system is very similar to the SimpliSafe system in that you install a series of window and door alarms around your house without the need for any tools or alarms. They are all linked up by a central device called CubeOne.

Unlike SimpliSafe, you can install a camera with the iSmart Alarm that will send you five photos of the area you're monitoring if an alarm is tripped. Because this system doesn't have the option to be monitored, you can then decide how you'd like to handle an alarm. When viewing a live video stream you can tilt and pan the camera with your smartphone.

Another distinguishing feature of the iSmart Alarm system is that you can purchase multiple "remote tags" that identify members of your family so that you can keep tabs on who is coming and going from your home.

The iSmart folks also make something called a Smart Switch. This connects to your existing home power outlets. You plug any device you'd like into the Smart Switch and you can control it remotely or set schedules for it to turn on and off automatically. This would allow you to create the impression of an occupied home by having lights, TVs and radios turn on and off throughout the day while you're away.

iSmart also gets raves reviews, although its lack of extra sirens, glass break sensors and the ability to link to a local police department (all features of SimpliSafe) might detract from this being a good option for some. Still, at the $199 price point, you get a lot for your money.

Michael Franco is a science and technology writer who secretly wishes he was an astronaut. His work has appeared in CNET, HowStuffWorks.com and Discover Magazine.