I want to switch 24V for an air solenoid with my UNO. Should I rig something with transistors(which I don't know how I would do it), or would I be better off trying to find a 24V relay with a 5V coil?
or would I be better off trying to find a 24V relay with a 5V coil?
A relay with a 5 volt coil would be called a 5 volt relay not a 24V relay.
Relays have two sets of specifications. The first set involves the coil, how much voltage (and if it requires AC or DC coil voltage) is required to activate the relay and how much current the coil draws when it’s activated.
The second set of specifications involve the output contacts of the relay, how high a voltage they can turn on and off and how much current flow can the contacts can turn on or off. These two sets of specifications are independent and it’s up to you to decide what ratings you require. Even with a 5 volt coil relay, most draw more current then you can safely provide from an arduino output pin, so using switching transistors to drive the relay coil is pretty standard. So only you know what voltage and current your relay will need to switch on and off, so it’s up to you to match relay specs with your application requirements.
Hope the helps a little.
better off trying to find a 24V relay with a 5V coil?
Probably, they are common enough, although that would be a 5v relay with 24v contacts.
I'd use a mosfet to switch a 24v solenoid. Does the 24v supply have a common ground with the Arduino ground or not? That makes a difference to the circuit and the type of mosfet you need.