What type of relays should I use in my application?

Hello,

I'm building application where I have to controle 30 relays with Arduino.

Since every relay need quite a lot of current, I don't know any better way of doing this by using shift registers. I connect the external power supply to shift rehisters and then address shift registers outputs (turning on/off relays) with arduino.

My question is: if there any, more elegant way of doing this? I know that Arduino cannot provide us with enought current for turning on soo much relays or maybe there are somekind of "low-current" relays that can be used here??

The best way for me would be to have just arduino nano with 30 rele shield that would be 50 X 50 mm big ( yes I am also limited with space...).

So maybe 4 of this shield that I offer?
Each group of 8 controlled by 1 shift register, the control signals can be daisychained,
It's basically this board, without the Uno part of the shield, to give a size estimate:
http://www.crossroadsfencing.com/BobuinoRev17/


And a youtube clip showing the power connections and control signal daisychaining

Controlling that many relays is not difficult. But we need more information. What is your output voltage and the max current. Is it inductive such as a motor or solenoid, or is it lighting. A little more information goes a long way in solving your problem.

Is this the same project as posted more than a year ago?
Handy to know, so we don't have to repeat ourselves.

forum.arduino.cc/index.php?topic=381250.0

Leo..

CrossRoads:
So maybe 4 of this shield that I offer?
Each group of 8 controlled by 1 shift register, the control signals can be daisychained,
It's basically this board, without the Uno part of the shield, to give a size estimate:
Cross Roads Electronics


And a youtube clip showing the power connections and control signal daisychaining
MVI 3167 - YouTube

This sounds fantastic. Can you plese send me and offer to my e-mail? I need to know the price and exact dimesions. My email is: as4159@student.uni-lj.si

Latching relays are a great idea if power consumption is an issue - they only need current for 50 to 100ms
whilst being switched. The downside is they keep their state when the power is off so when power is turned
on the system will be in whatever state it was before, which can be bad news.

if you are looking for a low current needed relay i may suggest you to use LCA182STR. It is a solid state relay and output current of arduino IO pin can turn on/off it directly.