Little home control project

antoinolachtnai · 02-03-2009 09:01PM #1

I am trying to get a little home control project going, something along the lines of http://www.dd-wrt.com/wiki/index.php/LaFonera_Hardware_Controlling_AC-Loads

I have a few of these routers spare. Can anyone give me a hand with getting the hardware part of this working? I am not much of a solderer, and I want to be confident that the whole thing is reasonably safe.

I would like to be able to control a couple of different types of loads with it.

It could be an interesting project for someone, not an awful lot of money, but there will be spare parts and routers going.

Antoin.

DublinDilbert · 02-03-2009 09:22PM

You'd be best off using some solid state relays to control the AC load. These are typically have a main power TRIAC and an optical TRIAC to control the gate of the main power TRIAC. It also means your 220V AC Power wiring is very neat/safe.

http://www.power-io.com/library/appnotes/solid-state-relay-terminology.htm

I Just googled solid state relay, and there's alot of mosfet devices coming up, these are typically for switching DC, you want something with a TRIAC inside.

Offy · 03-03-2009 10:21PM

Have a look at this http://futurlec.com/AC_Opto_Output_4.shtml
What are you looking to control? Lights, heaters, motors?

antoinolachtnai · 03-03-2009 11:11PM

Sure, I could use that, but I need something a little more simple. I only want to control one thing per fonera unit. I also want to keep the cost low and the size small.

What do I want to control? The things that come to mind are:

- heating (240v 3A)
- a doorstrike (12v)
- an immersion (20A or so)

the immersion is a little tricky, I grant you.

There are a couple of things out there that can switch all sorts of loads. For the bigger loads, could use something like:

http://cgi.ebay.ie/Merlin-Gerin-TL-16A-2-pole-contactor-15407_W0QQitemZ390033761136QQcmdZViewItemQQptZUK_BOI_CircuitBreakers_RL?hash=item390033761136&_trksid=p3286.c0.m14&_trkparms=72%3A1301|66%3A2|65%3A12|39%3A1|240%3A1318

http://cgi.ebay.ie/SSR-40A-SOLID-STATE-RELAY-PID-Temperature-Controller_W0QQitemZ260363786067QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item260363786067&_trksid=p3286.c0.m14&_trkparms=72%3A1301|66%3A2|65%3A12|39%3A1|240%3A1318

But really, it's the construction where i need the help.

DublinDilbert · 04-03-2009 12:31AM

A relay/contactor would do the job, you would just need to buffer the TTL output using a transistor, to provide the drive for the relay coil. Also make sure you've fly back protection for the relay coil.

There's lots of ways of doing this. You have to be very careful when switching AC power. You could get some DIN rail contactors fitted in your fuse board (on the cables supplying the immersion + heating), which you could control the coil from a 12V signal.

I like Solid state relays. Used to make them using a TRIAC which was fired by an optical triac.

antoinolachtnai · 04-03-2009 08:01AM

Yup, I think there are a couple of ways of doing it, but where I need the help is actually constructing the thing. It looks handy enough to do if you know what you're doing, but it will take me hours to solder all the bits and bobs together.

I'm not all that worried about connecting it to the actual power supply - I'm happy enough to do that and I will get an electrician in to help if I need it. But building little circuits is something I don't know much about.

Little home control project

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