the bottom line is:
you can use two pow.sup.s but i suggest you to use a 5V one for the relays and via a low-dropout 3.3v reg the eth. module
and a 9V one for the arduino\lm35
this way you will save the maximum energy possible because the arduino will draw max 50ma and you will use the 9V pow.sup. at 5% of power
2A is well enough but not below
switching regulators? let's not overcomplicate this project, we are already doing this...
and phone chargers are far away from being precise, they are not intended for make a reference voltage for a lm35
screwpilot:
sorry, i understand the smoke thing but i thought you are electrifying your fence
No it opens electric. It was already in the house when I bought it. Comes with a RF module. Will be nice job to figure out how that works and connect it to my home system.
For the 7805, find a buck converter. They are a switching converter and don't require a heat sink. Some are pin for pin compatible. Higher price but easier to work with and eliminate much of the waste heat.
So - you use a proper five volt regulated power supply which will power both the relays and the Arduino without problems.
Such as these:
The regulator in the "breadboard 5V + 3.3V power supply" is no better than that already on the Arduino - not suitable for your purpose. A suitable "LDO" TO-220 regulator on a small heatsink (with 10µF capacitors directly across its input and output terminals) will provide that from your 5V.
i want to make a point about 10uF capacitors on 78(x)XX devices
this summer i've read that this particular capacitance CAN make the regulator oscillate
because the caracteristic inductance of the device's output couples with 10uF caps and it may selfoscillate at around 10kHz or at least be prone to 10kHz bursts when the load varies quickly
i suggest ("i suggest" is becoming my catchphrase ) to use 1uF or 100uF with the usual 100nF
also...
offline switching power supplies are not raccomended for powering the arduino on the +5V\vcc
because optocouplers are way more susceptible to variations due precision\temperature than the internal reference of the onboard regulator
especially for this application that involves lm35s
lm35 don't adapt their output when there is a variation on the vcc line
this will vary the adc of the arduino and screw up temperatures
And I did order an L7805 and an TO-220 with some diodes and some capacitors (condensatoren in dutch).
But first I can test and continue with my breadboard power supply.
Compared to my drawing I will reduce the number of arduino's it cost me too much power to keep everything running 24/7. So I am going to play with the shift registers to address 16 relays with this arduino.
I built my first Arduino with a nice little website. But that costs way too much memory now. So I reduced the webinterface drastically. It now spits out xml.
I am now working on a HTML5 standalone webpage, which I will pack into an apk for my android devices.
I am a senior software developer, but I hate HTML and css. That''s not the kind of development I usually do during working hours.
However until now I managed to come to this:
Later on I will make a webapp running on a webserver so I can get statistics and run programs and activate timers and so on.
But first "simple" stand alone HTML 5 page. It's so stupid to say that I cannot switch on my light when the webserver has crashed for example.
Thanks! but I just bought the LM317T spanningsregelaar TO-220.
Is it now okay with my power regulators or do I need to buy some others?
I did buy some capacitors diodes and elko's.
I found a schema somewhere on the internet.
an lm317 needs two resistors to be setted to the right voltage
and it's an old fart of a component
but can be used
if you want 5V on the 5V output of the breadboard adapter you need to supply it with at least 9V
otherwise it's no point to use a 5V regulator if you already have a GOOD 5V p.s.
you just need a 3.3V reg. for the eth. board
i suppose you have already got there
relays on the wall sokets? clever!
just consider the max amperage of the relays
screwpilot:
relays on the wall sokets? clever!
just consider the max amperage of the relays
Yes when it's christmas I want to be able to turn the tree on and off too
Same I will do in the bathroom so no shaving machine adaptors work uninvited.
The relays on the boards I bought are 230V 10A. 10A is a whole lot as I read it. Now I will not use it for my high-end audio installation. That even has it's own fuse and cable and that's seperated from the rest of the hous' power network.
But I checked for instance the TV and it's much less than 10A and it's an old 42inch plasma.
I can put some fuses in front of the relays, I already have been thinking about that.
........
