I am looking to control a 24VDC 50ma relay using a 5v signal from an arduino. Would the attached circuit work?

 

If you don't need to isolate the 24vdc, a couple of 2n7000 would work.
Max.

 

Yes I see that now. However, if i did want to isolate the 24vdc then would this circuit work if I separate the Gnd signals?

Am I right in saying that this circuit is capable of controlling a 150ma max load?

 

Probabally, depends on the contact rating of the relay, although 150ma is pretty low.
What is the nature of the load?
You maybe could also use the same circuit with the 2n7000 in place of the relay and switch the load direct if low voltage DC.
Max.

 

The data sheet shows an absolute max Ic of 150mA. I would never design a circuit that relied on an absolute max.Test conditions describe an Ic of 30mA. So, you may be ok at 50mA. Generally, I've seen optos used to drive transistors to drive relay coils. Note that your usage will have the relays triggered by a logic high.

edit: by the way, you'll need a flyback/backEMF diode to prevent damage to the opto's transistor.

 

Probabally, depends on the contact rating of the relay, although 150ma is pretty low.
What is the nature of the load?
You maybe could also use the same circuit with the 2n7000 in place of the relay and switch the load direct if low voltage DC.
Max.

Isn't it the coil rating of the relay to worry about?

 

Isn't it the coil rating of the relay to worry about?

Yes I see it now.

@jonfarrugia what are the relays switching?
Max.

 

the relays are switching a 120VAC 20amp load

 

would that be a diode across the relay coil or across the opto coupler?

 

would that be a diode across the relay coil or across the opto coupler?

relay coil. A 1N400x would be fine.

 

Remember to reverse bias it!
Max.