Question about a DC Relay

[Hawaslsh]

Hello all,

I have been burned in the past when it comes to relys, so I wanted to ask and make sure my understanding of a particular relay was correct.
I am looking at the **broken link removed**, It is a normally open DC relay.
my question is: can the LED be driven directly from an Arduino (Atmega328) output and would it need a current limiting resistor?
Also, Some relays require a zero crossing in order to fully turn off, Since this is LED driven MOSFET, that isn't the case?

Thanks in advance!
Sami

 

[Carry for cents bazar]

This is an opto relay. It will need a current limiting resistor for the 1 and 2 pins, it can not be driven directly by the arduino, it will require a driver. This relay is not good, I recommend using a different one. Despite that the datasheet shows the voltage drop over the diode to be 1.2V to 1.5V, its not good to drive it from the Arduino pin. It takes a maximum of 50mA control current, which is too high for the Arduino. You can use a MOS 2n7000 or similar to turn on the relay and connect the MOS to the arduino pin. Like this you wont need a current limiting resistor, but its good to have one or to limit the current with a bipolar transistor.

 

[KlausST]

Hi,

The input device is a LED, and as every LED it needs to be current limited.
You definitely need a current limiting resistor.

The LED needs at least 5mA, 1.5V to be ON.
Maximum LED current is 50mA.
To operate it at the minimum current is no good idea.
In the datasheet it is specified at 10mA... seems to be a useful value.

I didn't read the Atmega datasheet. Please read regarding "output characteristics"
There you will find whether it is able to drive 10mA .... and what the according output voltage will be.

The datasheet does not mention zero cross, thus don't care about it.

Klaus

 

[dr pepper]

470 ohm in series with the atmel pin should do it.