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Comment by masonhensley | Hacker News Reader

It is a bummer that the Belkin WeMo's are going to be so expensive.

http://www.belkin.com/wemo/ ($50 switch, $100 for switch + motion sensor)

If I was looking to dip my toe into some home automation toys, I would rather pick up a Nest($250) and one of the iOS/Android powered home locks (~$300) than the equivalent # of WeMos(at $50/per)... but that's just me. To get real value out of a WeMo system, I figure you need at least 10 spread around your house.

If the WeMo's were $20-25/ apiece and they had a wall switch version, I think Belkin & IFTTT would be a game changer in the home automation space.

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>one of the iOS/Android powered home locks (~$300)

Check out Lockitron! (https://lockitron.com) - we come with an API, no monthly fee, and a variety of locks that will work on most doors or apartment buzzer systems.

What's the solution when your phone is stolen/offline/out of order?

Lockitron also offers locks with a keypad, and every lock comes with a Bluetooth keyfob for emergencies like this. <3 lockitron.

I don't see any keypads on the site. Is this true?

A keypad backup is a very desirable feature to me. Possibly to lots of others too, I would think.

Ah, yes, a bit of a secret those. We're currently doing field tests with our keypad locks.

$50 for the switch isn't that expensive given (a) it's WiFi controllable; (b) there's not much in the way of alternatives; and, (c) it's consumer focussed.

Prior to the WeMo your best option for power socket control (as an amateur/DIY/Maker) was something like one of these:

* http://www.sparkfun.com/products/10747

* http://www.pwrusb.com/order/

Or hacking a radio remote-controlled power socket. All of which require additional work.

I'm waiting for a 240 Volt version with NZ connectors.

So we need a RasPi with either a $2 solid state relay (on/off) or $8 triac (on/off/dim) and a powerline ethernet interface.

Then its about $45 and open source. Of course it isn't in the fancy package.

Of course if we want to go that route, then an open source board using say an ARM Cortex M4 (like the ST Micro 32F4) would get the parts cost down around $10 - $15. I'm guessing that is how Belkin implements this as $50 is about 3x that cost.

Using a Raspberry Pi is massive overkill. A $20 XBee module, a $3 microcontroller, and a custom PCB will do the trick; you can then control it all from your PC with another XBee radio. It'll probably be easier than making Linux deal with your relay, because microcontrollers are easy mode. Even an Arduino would be expensive overkill for this project.

Once you add a power supply for your micro, connectors, and an enclosure, you'll probably be hitting the $50 mark, if not more.

You also need to be very, very careful when working with the mains. I wouldn't route a board that works with it unless you know exactly what you're doing.

    It'll probably be easier than making Linux deal with your relay

At least on the Beagleboard, GPIOs show up as files that you can write 'high' and 'low' to, making it easy to switch relays.

How is it is massive overkill? The total amount of structure is the same in both of the solutions. Only in the one you mention it has less gates. Same amount of input resources. Gates a free. 5 years from now kids will be making LEDs blink using vixie cron and a python script talking the GPIO lines of a 32 microprocessor and this is O.K.

How is it is massive overkill?

A BCM2835 (Raspberry) uses ~2W, while an ATmega186 (Arduino Duemilanove) uses ~0.027W. So yes, massive overkill.

I think you mean the ATMega168 and its power consumption is somewhat less than 0.0027W, while the BCM2835 is more like 2.5W, but regardless, I think you're defining overkill in terms of power, which is only one dimension, probably not the one the comment was referring to.

It's a bit like saying using a tungsten lamp is massive overkill in lighting a room.

Also, I'm concerned about the idea of it taking power even while everything in the house is off. Is there a page somewhere that addresses the power usage concern?

I tested a preview unit. It was something like 0.3 watts, if I recall correctly.

Perhaps if they added integrated batteries that only initiated a power draw to charge when they reached a specific level they wouldn't need to draw power from the grid constantly. Expensive way to solve the problem though, perhaps.

That would use more power because of losses in charging the batteries and standby loss in the battery themselves.

They could optimize for lower power. 0.3W seems pretty high, I would bet they could reduce that by a factor of 10 if they tried

Can you still send 802.11b/g/n with 0.03W power consumption?

These guys are doing it using just 0.00015W

http://supermechanical.tumblr.com/post/25189115532/its-all-o...

Of course it depends on how often you "call home" to check for any information. What might be acceptable for monitoring temperature would not work for a switch when you expect immediate response.

It might have been 0.03W. I’ll need to check again… It was either 0.3 or 0.03.

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