I am a software developer and recently I started with Arduino to build my own home domotica / alarm system to get experience with the board, to build more things after that.
Now I am a software developer but a total electronics n00b.
While my older brother got an electronic building box for kids, when I was the same age I got a Commodore 64 and now I regret that a bit.
So I have an arduino uno, connected to env28j60 lan a 6 relay board and 2 temperature sensors (LM35).
I build a simple webserver in it so I can control it even while the complete system with multiple arduinos is not finished yet.
I have a problem that more starters have on the internet. When I switch a relay the voltage seems to drop and this effects the reading of the LM25.
The advise is add another power supply.
Now the questions:
The relay board needs 5v can I hook this up directly to the 5v of another usb cable? Or do I need extra parts inbetween?
What is a better way of powering the arduino and extra modules with 1 power supply? And what power supply would i need for that?
Samsung has those nice small USB phone loaders. but it's not small enough for me. I am considering building an arduino nano into a wall mount light switch. The Samsung usb power adapter would be small enough when it would had no case and no power plug. Can I buy that 5v power supply somewhere without the casing?
powering ralays from the 5volts (common) line is not the best way (but can be done)
i think that the ideal scenario is to power both the arduino and the ralays with 12V (on their 12v inputs) if possible, and power the sensors and LAN with the arduino 5V
can you post a photo\specs\webpage of the ralay board? it will be very helpfull
if the relay board must be powered at 5V you can use a 12v power supply and power the arduino, the same powersupply will go also to a heatsinked 7805 that powers the relay board
common ground (of course)
I would like to power this.
I can try the option with the 7805 and 12v.
but i tried already a 12v 1000ma adapter and the ardiuno went on but no lan no serial communication.
Please don't put anything into a switch box in the wall that has you house power in it. If anything occurs, such as fire or accidental electrical contact, you personally will be responsible, not you insurance company.
That is why we use a "wall wart" that has a UL number on it or a "CE" number for Canada, and that is why you can't find one without the plastic housing.
I understand that i must be carefull. However i am renovating my home and i want to domoticise my house.
i have no problem with connecting 220v power lines.
I build half of my house myself. Its not a problem in holland.
i am used to pc for which you can buy an internal power supply.
only a pc power supply is a bit noisy and overdone and my system must be energy friendly.
When this layer is finished i will build a central control unit. So all will be combined into a thermostat, an alarm system, light system inside and outside the house. Bathroom fan control. Autimatic lights off etc,night lights for toilet visit.
with html 5 andriod app
your project is more good looking than those of mine but i can only "suppose" you are powering the ethernet module with the arduino 5V output, if so IT MUST power on the ethernet module when 12V is applied on the Vin
9-12V power supplies are common too, you may find em on the internet and you may open em
and... i insist for the 12V solution and a 7805 for the relay module (maybe 9V for saving energy but not below)
if you are going to place the system into a wall near power lines you need to shield it, you also need shielded cable for the lm35, don't use the shield of the cable as ground!!! you need to use an inner wire as ground, the shielding will be just connected at JUST ONE end at gnd (usually not the sensor end)
instead of the nano you can use the ProMini, it's cheaper and smaller (but the onboard regulator may not be able to power the eth. module)
i dubt that the 3.3V output of the UNO can successfully power an ethernet transceiver, the ethernet cable must be somewhat "beefed up" with energy and the 50mA of the 3.3V line may not be enough, read the datasheet of the ethernet chip for knowing more
there's no 3.3V on the nano
IF your ethernet module can be powered with 5V, do so
i'm starting to think that your current 5V pow. sup. delivers more than 5V, it's a common (big) problem with cheapos, this will overdrive the 3.3v regulator and make it work "good" but superoverheating it, the situation changes when you power the entire thing with the UNO 5V regulator (at 12V) that is precise
i think your project is skyrocketing in complexity\cost\energyfriendlyness
the enc28j60 CANNOT be powered at 5V, it's logic inputs are 5v tollerant but that's it
you need a 9V adapter that powers...
1)the arduino in the Vin
2)the heatsinked 7805 that consequently powers the relay module
3)a 3.3V heatsinked regulator that consequently powers the eth. module
you can try to power everything with a good 5V source and use a low-dropout 3.3V regulator, but it's not a clean way and you have already discovered that when a relay switches, the voltage decreases messing your temperatures
any electronic compenents seller sells 7805s
any piece of alluminium can act as an heatsink
the output of the 7805 is independent from the 5vVcc of the arduino\lm35 system (infact it's the clean way)
AND... check your 5V pow. sup., it may not be 5V and damage a lot of things
Paulcet:
The breadboard power supply is not more efficient. It has two linear regulators, similar to 78xx. You need a switching regulator.
It's not more efficient, but if I use the breadboard power supply to power the enc28j60 ethernet module and the relay module and I use the USB of the Arduino to power the arduino with the sensors.
Then at least I should be safe, right?
It should not become too expensive to buy, it should not be unsafe so my house burns and it should not be consuming a lot of power since it's 24/7 on.
That's why I thought of a double USB power supply with 2 usb cables powering the breadboard power supply and the arduino. It's handy since the breadboard power supply supplies 3.3v and 5v. and I need 3.3v for the enc28j60 and I need 5v to power my relay board.
I was reading something about the arduino's sleep mode. I have try a bit if that works and if it wakes up fast enough.
i'm not getting if the arduino pow.sup. is EXACTLY 5V and the other is somehow 9V, it must be this way
cheap pow.sup.s can deliver more than 5V and destroy your arduino, and i still suggest you to use the arduino onboard regulator (more precision for the lm35 (and this may be highly necessary))
powering that regulator module with 5V is useless, if you power the arduino directly with 5V you can power the relays with another 5V pow.sup. and you just need a 3.3 low-dropout regulator for the eth. module (you don't need an entire pow. module)
if you are going to use two small identical powersupplies you must connect their 220V sides the same way, i mean LIKE you are connecting "+ with + with battery+" and "- with - with battery-", it's a safety precaution since you are connecting their grounds
