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muyinteresting

Member Since 31 Aug 2010
Offline Last Active Mar 05 2011 10:42 PM
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Posts I've Made

In Topic: Netduino Plus home automation

14 October 2010 - 04:35 PM

hey guys very cool ideas. I do have an electrical license and would be happy to lend info if needed.


My biggest hangup is relay size and electrical safety and code adherence.

Do you live in the US or Canada? There is zero use for me to actually get super excited about this project if I can't be 99.99% sure that it won't burn my house down.

I've been doing some reading, and I've found that the general consensus is that relays should only be pushed to 70% of their rated resistive load values. I also read that I should be very aware of handling split second huge current draws that might just pop the relay. Things like vacuums, electric kettles, etc. stuff that draws 5-10A resistive load, but when starting up the load can easily be 2-10x higher than that!

I had purchased some 15A @ 120VAC rated relays for $1.19 from Mouser Electronics, the contacts are quite small, and after reading up on it, I'm sure the only thing these ones can click on and off would be light bulbs.

So I need 30A @ 120V rated relays at minimum to make sure I have a high amount of room to work with. Only problem is that the price increases quite a bit.

I also found that there is a serious backing for the use of optoisolators for switching stuff like this. Separating the high voltage from the low voltage and stuff about not putting high and low voltage in the same box without some solid isolation.

If you can get back to me on wire gauging, relay size, and if you are in the US or Canada, a quick lesson on Elec code 101: How not to burn things, that would be great.

In Topic: [PENDING/SLOW MOVING] Home Automation With The Netduino

14 October 2010 - 04:05 PM

Quick note: I'm a student, I'm poorer than dirt at the moment. So no hardware purchases yet, just planning and coding and stuff. The interest is really great though. I thought I was just crazy. No one I've talked to so far about my plan has showed much interest. I guess you need a working system to be able to convince people. The day I can use my stereo remote and a tablet to control my stuff, I will be happy. There are 15 buttons on my Cambridge Audio that are unused because it is a combo remote for a matching CD player as well. Building an IR receiver is next on my list, and it will be just like the other remote controllers, wireless and such. Press the numbers 1-15 to change the lighting pattern in the room. :D Also, thanks for that link to the SNUPI and IQRF stuff, pretty cool sh!t.

In Topic: [PENDING/SLOW MOVING] Home Automation With The Netduino

13 October 2010 - 06:33 PM

Oh, I am just using the netduino as the "master" controller since I already have it and I can code things to leverage the power of .NET MF. It is going to be the glorious bridge and master of all of this chaos. As for the software side, the eventual plan is to have the server on the netduino itself. So that the controller devices (the tablets, phones, etc) will connect directly to it. For now I'm going to run a dedicated machine with a serial to UART converter to talk back and forth with the netduino. The serial host machine is gonna have a small windows forms app that will just take the command sent from the client via the IP network and push it over in full to the netduino for processing. So for now its Client ->(IP) PC Server (Serial) -> Netduino ->)) Wireless controller. So to be the master controller, and to handle multiple client devices connected, I do need the netduino for this one. Some will argue that I should ditch the dev board(netduino), but for my own use, it works just fine. I'll figure out how to design my own board that needs only the components I need (like the Amtel sported by the netduino), and directly soldered stuff as opposed to on the headers. However, that is a LOONNG way off. To do the actual work (the wireless controller), I am considering buying a JeeNode as a dev platform, and then I will find every way to squeeze the cost down as far as I can with a custom solution. I might have to consult someone that knows PCB design for that one. Basically, I will probably end up taking the (idea of the) JeeNode and stick it on a custom PCB that doesn't include the extra components like the unneeded pin headers, etc. Cutting costs wherever I can. I hoped to actually prototype the hardware and eventually turn it into a legit product, but since I will have to draw upon so many people to make up for my lack of knowledge, putting the software AND the hardware plans open source is the best way IMHO. Green automated homes for everyone! Random goal: Complete the majority of the project goals for a total cost of well under $500 in hardware.

In Topic: Netduino Plus home automation

13 October 2010 - 03:44 PM

I guess I have to explain my vision. My seemingly overkill dream pretty much. I should be documenting this in my own thread, but since we are already discussing it.

When I come home, I want to be able to pick up the 7" android tablet (around $200) on my coffee table, swipe through a couple menus and control my house. Other options would be a windows application, an app for my blackberry, or the app on an android based cellphone. They all run the same control routines, just shinier interfaces on some of them.

I want to see:
Environmental data (Temperature, humidity, light readings) for every room
Electrical status (per OUTLET current draw, which outlets are on/off, etc) for every room
Electrical & environmental combo map on top of a floor plan
Home security status (which windows are open/closed, is the main door deadbolt locked) for every room

I want to be able to:
Change states of outlets, light fixtures, etc. (Turn lights/outlets on/off, set lighting patterns/profiles)
Control home appliances (via IR for HiFi system, mechanical control with servos, etc).

As for actually powering the controllers that would actually provide this info, If you find a very small (you dont need alot) supply from something like a USB charger, it seems small enough to fit into the box. The total supply available would be around 5V 500mA, which is more than enough to power the stuff, trigger the relay, and do whatever else.

For the wireless controller side, something like a JeeNode (which are pretty small) could be used. Just don't put the pin headers on. I think something more custom would be in order for a more wide-scale deployment though. $22 just for the controller isn't worth it when you are only using 2 pins (1 relay, 1 current sensor). If that cost could be cut down to under $20, it would be very viable for a small module.

A controller dedicated to receiving queries and sending back data or responding to controls.. it really doesn't need a 32 bit MCU with >9000 mhz of power. So if you wanted, you could probably cheap out hard and use an ATMega168 and only use the pins you need.

I was thinking about a simple command set:

RELAYSTATE (CONTROLLER ID) (RELAY #) (STATE)
SENSORSTATE (CONTROLLER ID) (SENSOR #/PIN #)

The Controller ID will be set by using an analog pin on a DIP switch set of resistors.
It is an 8 bit ID. Separated into a GROUP and a TARGET. The first 4 bits indicate the group, the last 4 indicate the the target controller itself. This allows 15 groups of 15 controllers, which is way more than anyone would need unless they have a mansion or something.

Total resistance = ID values. So you have the row of switches to set the ID...

|0|0|0|1|-|1|1|1|1|
This controller is #15 of the first group. Go through the binary values as you wish.

Stuff like that. A really easy command set. The difficulty comes when encounter the need to secure these wireless connections.


brainstorms

As for the actual switching that works even without power, you can use the usual dual switch wiring method. Since the relay is just a fancy switch, wire it like you would wire a common SPST switch in your house, just this time, they are inches from each other instead of having one at the door and one down the hall to control one light.


Midterm test time! :o

In Topic: Netduino Plus home automation

13 October 2010 - 01:47 PM

For the lighting control, which is my primary focus, I am giving up on the established devices such as X10's. I'm going all out and planning a custom made solution involving Relays, wireless microcontrollers, and the like all packed into something small enough (and safe enough) to put in the empty space of the electrical box in the wall. While the X10 boxes you can buy online are nice and great, they are big and ugly and don't really fit in. My idea is to have something that is practically invisible and can be dropped in place or installed in a new home. Plus, I want to make a sexy interface for android devices, blackberries, and PCs to view real time status information (environment data, door lock status, etc) and control devices to turn on lights and appliances laid out on a floor plan. However, I should but the giant disclaimer up that I am NOT an electrician. This is probably not going to be safe. I'm gonna have to consult the electricians and EE's at my college for this one. More or less making sure I'm not going to burn down my apartment. Back to studying for a big midterm test. ;o

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