That's a bloody good point, I vaguely remember being told that once (possibly in first year), but never really thought about it again.

Just done some reading and seems it's actually perfectly fine for digital signals (up to about 2 GPS anyway), but can be pretty devastating for analogue.

http://www.sigcon.com/Pubs/edn/bigbadbend.htm

http://www.ti.com/lit/ml/sloa089/sloa089.pdf

I haven't done any multilayer boards, but when I looked at Ant's design I did wonder about interference between the traces running on top of each other. Decided it probably wasn't going to be an issue on that board, however I didn't think at all about capacitance. That may have a much bigger impact. There's a method for calculating the parasitic capacitance in the second link there, might be worth working out what it would be and seeing what impact that would have on the design.

(giggle) do it. At worst you'll have some nice looking book marks.

For a board that simple it would be pretty easy to just make sure the traces weren't on top of each other anyway - no worries either way then. 

what are you making?

That would be a wifi temperature sensor using an esp8266 module.

I'm going to try laser etching a pcb (Well, the mask anyway, still needs to be dumped in ferric chloride to remove the copper) tomorrow. No vias or through hole plating but should be good enough for my needs.

I should have just ordered the PCBs rather than wait for the parts that still haven't arrived.

that's what i thought... i keep meaning to get around to making a few of these to monitor the house + feed back the data to somewhere.... are you battery powering them? (I'm fairly sure the circuit diagram doesn't tell me this... )

be interested to see how you get on (i'll notice your reply next time i swing by in 2 years time no doubt!)

Gah. I have about a hundred quids worth of stuff floating around somewhere. Need a hyperloop to China :C

Every building should have a mini hyperloop for deliveries, linked to everywhere else in the world so items can be sent straight to your home quickly.

I've currently already got sensors in various places using Arduinos+nRF24 transceivers+ds18b20 temp sensors. They make up the temperature part of my central heating setup. They're powered by USB supplies. Not made anything that is low-power enough to run long enough off batteries, though that would be the ideal situation, but plugging them in isn't an issue where I've got them located.

Just thought I'd give the ESP8266 modules a go because they're dirt cheap and my wifi network is better than the nRF24 system. Hopefully they'll have better range and reliability. 

cool; what do you do with the data ? send it somewhere? and how does it control heating.... made something?

A Raspberry Pi receives it and sticks it in a mysql database.

I've written a script that is run every minute and works out based on various factors whether to turn the heating on. Target temp, current temp, target room, whether I'm in the house etc.

The boiler has an Arduino, relay and 433 MHz receiver, that's the heating switch. The RPi transmits a 433 MHz signal to turn that on or off.

i see. any zoning?

Nope, I've looked at wireless TRVs but that's a step further than I can be bothered with right now. (plus the expense)

I can already pick a target room along with target temp so when that room comes up to temperature the heating goes off (or maintains that temperature).

I've also got an "auto room" setting which currently means that if either the bedroom or living room get above the target temp it turns off. I may add an "auto room both" type setting where it only turns off when /both/ the living room and bedroom hit the target temp.

The best bit though is having a /graph!/ to look at. Although my dad did ask my Uncle sarcastically if he'd like a graph of his living room temperature and he said no.

Yes I copied Ant and made one too :)

I didn't know you could get wireless TRVs. Interesting. Could you make your own with a normal TRV and a motor to turn it on/off? How many sensors you got in your house now?

Like the look of that... if/when I can be bothered I'd like at least some graphs... make me feel good about myself if I improve insulation or something....

Did one of you write code? Or is it something off t'internet somewhere?

Re TRV's - yes, you can get battery powered/wireless ones, there's some where the protocol has been reverse engineered - eq3 MAX! i think they are called - so you can talk to them with other stuff. You could make an electric actuator to replace a trv head I guess, maybe a stepper motor turning a bolt or something to get the up/down movement - but I'm fairly sure that if I made it it'd look too shit to put round the house.

If I did anything, think I'd add 2 port motorised valves on the feed to each rad where they split from the manifold under the floor upstairs (rads all fed from a central point here), or maybe group them into zones of a few rooms and put a 2 port valve on each zone (with one manifold per zone). 

I believe we both wrote our own code with a similar idea.

Mines just a bash script, running as a cronjob, nothing too excited.

As Ant said I copied his idea but wrote my own code. An embedded web server in a C++ program. Doesn't do such clever stuff as Ant's though, no temperature control, just switch it on for a certain amount time. Really nice to be out somewhere and the heating on so the house is warm when I get home. And lots of fun soldering up the sensors.

Graphs are good :) I want more sensors so I can have my whole house on my graph. And I did plan an outdoor sensor house thingy whatever they're called.

I worked in a house where the plumber (owner) had zoned his whole house with a central manifold. I don't know how useful that is in a house.