I want to use an Arduino (5V, 0-40 milliamps) to control some switches, which in turn control a high current line (12V, 40A,) but the coils in the relays which I use are too heavy for the Arduino to pull off.
The relays don't turn on.
What are my alternatives to relays and separating the low power Arduino from a high power line?
Is there a way to use MOFSETs in regards of separating the power lines?
But the relays which I use use too heavy coils for the arduino to pull off.
If you are connecting relays directly to Arduino output pins you might destroy your Arduino! You can use a power MOS-FET to directly drive the relay coil like this:
Schematic by Jeff Sampson.
Instead of motor you connect the relay coil.
To separate Arduino from power line, use an optoisolator like this:
Schematic by Lewis Loflin.
Usually optoisolators are used to separate low from high voltages. They have nothing to do with the current. The MOS-FET handles the current.
There is no need for relays as long as your MOS-FET supports the 40 A current. Just connect the load in series with its drain-source pins.
