Wesley's Tool-Box

Up until now, I’ve been driving the car my parents used to drive, and I had been putting off on buying my own until something that could satiate my fondness for technology would come along. And I finally found that car - Chevrolet Bolt EV, a fully battery powered electric vehicle. I pre-ordered this year’s version in January, and was expected to get it by late July, but I got lucky and I picked it up today. The car is very responsive, which I like.


The car wasn’t fully charged at the time of the handover - it only had enough charge for about 150km of driving. So I’m charging it at a service area as I write this after driving about 50km. I still have more than 300km to go, so hopefully it’ll get charged enough for me to return home.

Power Silicon Ltd., a Korean manufacturer of LED lighting and power supplies, has expanded its portfolio to smart lighting late last year under its "PSAurora" brand. In order to promote these new products, the company was looking for people to test out and review these smart light bulbs. The smart lighting market is becoming crowded these days, so I was curious to know if they could hold their own and put in my request.

After the request to review was accepted, two bulbs arrived in the mail - the globe bulb version of the Smart Bulb and a handy Smart Portable. Both were controllable by Bluetooth Low Energy (BLE) from a smartphone using a companion app.


Each bulb came in a cardboard box adorned with English product description and basic user instructions. A much more detailed single-sheet user manual in both English and Korean was in the boxes. The bulbs themselves were largely made of plastic, but they did not feel flimsy and were well rounded.

At a first glance, everything seemed to be there for a user to get everything up and running, including installation of the app and controlling of the bulb. However, I did find some room for improvement upon deeper inspection.

Apple HomeKit platform goes back to iOS 8. It was not very fleshed out at the time, needing more polishing over the years. Last notable change to HomeKit was made in 10.2, which enabled device notifications. This, along with other improvements in iOS 10, led me to think that HomeKit was finally in a "usable" state. Thus I have invested in the HomeKit ecosystem since early April of this year, around when iOS 10.3.1 came out.

As I gathered enough tangible material to share, I did a 5-part write-up of my HomeKit experience, spanning sensors, lighting, and energy control. I felt that my 5-month experience in a non-American environment may be of use to many people who are considering the platform.

1. Moving to Apple HomeKit with Elgato Eve
2. Philips Hue adds light to the HomeKit setup
3. Controlling 220V Power & Light with HomeKit
4. How much power does HomeKit use?
5. On installing and configuring HomeKit lighting

But now, big changes are coming in the coming weeks. Most notably, the GM(Golden Master, finished version) of iOS 11 will come out in two weeks, as Apple's new iPhone announcement will be made on September 12, 2017. It will contain significant improvements for HomeKit. As noted in the 5th post, Philips will expand the range of Hue products that will be recognized in HomeKit. Elgato has announced five new HomeKit products including lock and smoke detector.

All this means that my iOS 10-based HomeKit write-up should be wrapped up at this point. I'll come back to this topic as the dust settles and I had my hands on the new features and products.

There are some things to consider and take action when you're installing smart lighting, HomeKit enabled or not, around the house. For the light switches, the biggest concern is the presence of a neutral wire. In most cases, you need this for a smart switch to function, but many switch boxes omit this and make things complicated. To see why things are like this, we need to take a look at the circuit diagram.

For a light to turn on, it has to connect to both ends of a power source. This is generally a single-phase AC power, which can be derived from a 3-phase AC power by using one of the phase wire and a neutral point. The wire connecting to the neutral point becomes the "neutral (N)" and the phase wire, the "live (L)" as seen in the diagram.

With a regular switch, all you need to do is to connect or break the connection between the live wire and the "load" wire leading up to the lamp. Therefore, a switch box only needs to have the live wire and one or more load wires coming out of it. Number of load wires correspond to the number of controllable light fixtures, of course. Neutral wire could also be present, but it wouldn't be connected to anything because there is no need to.


The situation becomes different with a smart light switch. In order for the control module in the device to work, it also needs to connect to both ends of a power source, but at all times and independent of the lighting. As the live wire is already present, we need to add the neutral wire to the device as seen in the circuit diagram. With this configuration, the switch connected to the live wire and the load wire could be controlled either manually or by the control module. This is the reason why most smart light switches require the neutral wire.

The rare exceptions that can forgo the neutral wire have the control module connect between the live and the load wires. The module itself consumes little power and a very low current leaks through the load wire in the "off mode" so as to effectively prevent the lighting from turning on. But this generally requires the lighting load to be sufficiently large. If not, the leaked current may cause the lighting to flicker or cause other problems. In other words, this solution isn't as widely compatible as the switches using a neutral wire.

Home automation devices have to be on standby at all times to respond to commands. This means that the baseline power consumption will increase as more devices are added. So if you're installing them not just for convenience but for more efficient energy use, you have to be conscious of the level of power that they may entail.

Unfortunately, detailed power consumption data are not usually found in the technical specs, likely because they are not deemed important. I had to take individual measurements to get the whole picture, and here are the results for the HomeKit devices I have.

[ Terminologies & Explanations ]

Off: The device is connected to the power but is turned off (i.e. standby mode).
Min.: Device operating under the lowest power mode possible.
Max.: Device operating under the normal or highest power mode possible.
(Minimum and Maximum values are measured with no external apparatus attached.)
Rated: How much the the device is rated to draw electricity at maximum.

1. Or 220V mains. 1,800W for the U.S. mains (120V).
2. For the LED and CFL bulbs. 600W for incandescent and halogen bulbs.
3. The indicator LED light is turned off.
4. For the LED and CFL bulbs. 1,800W for incandescent bulbs.
5. Only one switch is turned on.
6. Steadily decreases to the stable level (9.2W) over the span of 30 minutes.

It became fairly evident that the consumption profile is quite different between manufacturers even though the devices serve essentially the same purpose.