I want to control AC devices using Arduino board. Would like to know how many devices can be controlled simultaneously using a single

• Arduino Uno (or)
• Arduino Mega 2650

Since I am not a electronics guy, I am not able to understand the digital and analog pins info and hence would like to know the answer for my above query

Regards

 

As many as you wish.

 

But, the power supply is limited to 7 - 12 V dc and 40 mA current. Assuming I use Mosfet (i think so) to switch ON/OFF the devices, beyond a certain no. of Mosfet, for sure I would be requiring some external power for Mosfets. So is it possible to use external power apart from the dc supply of the arduino?

Also, Thnx for the reply.

 

Aside from the on-board I/O the amount of control 'channels' depends on the interfacing scheme.

If you just wish to use on-board I/O then look at the Arduino website (arduino.cc) for a comparison of discrete capability of the units you mentioned otherwise you could design your own using the on-board I/O as an addressing function.

 

But, the power supply is limited to 7 - 12 V dc and 40 mA current. Assuming I use Mosfet (i think so) to switch ON/OFF the devices, beyond a certain no. of Mosfet, for sure I would be requiring some external power for Mosfets. So is it possible to use external power apart from the dc supply of the arduino?

Also, Thnx for the reply.

Yes, you can use external power other than from the Arduino. You might have to do that if you're using devices (say motors) that require more than 5V, or just more devices than the Arduino can source/sink current for. Multiplexers can easily let you control more devices than the Arduino has pins.

 

I think SSRs would be better for controlling AC loads than MOSFETs

 

Thanks everyone for their replies.

btw what is an SSR (abbreviation please)

 

SSR = Solid State Relay

 

I have yet another doubt. Since my program will be hard-programmed into the microcontroller, is it possible to use my arduino to perform alarm based tasks (say daily alarms, weekly alarms, etc and these schedules will be changed at user's will) to control devices?

Tried googling for answers. But still not convinced.

 

I have yet another doubt. Since my program will be hard-programmed into the microcontroller, is it possible to use my arduino to perform alarm based tasks (say daily alarms, weekly alarms, etc and these schedules will be changed at user's will) to control devices?

Tried googling for answers. But still not convinced.

yes.. there is very little along these lines that the Arduino can't do..(Sounds like a fish tank project).. Many add a RTC (real time clock) IC circuit (like a DS1307) and that can be used to setup time/date based functions,etc... Simply googling "arduino DS1307" should give you plenty of information/videos,etc..

Frankly I'd get an Arduino Mega which includes way more I/O ports than the uno.. This will allow you to switch MANY loads without the need to incorporate multiplexing IC's or similar to expand the number of uno I/O's..
If you want to be even cooler get the mega with the android adk.. This will allow you to use your android smart phone to control it too.. ie switch loads on/off,etc.. Or an ethernet shield to allow remote control from anywhere in the world via a web browser.

 

How many tasks depends a lot on the desired response time and programming skill.

 

Got it. Thanks again