I want to control a 24V actuator using an Arduino Uno. I realize the Arduino cannot handle the power demand so I am using an external 24V source. Can you please guide me on the basic set-up?
I want to convert the digital 5V signal to 24V with an amplifier. I will use PWM later to vary the speed. For now, digital 0V and 5V amplified to 0 and 24V is fine. I am looking for suggestions on what type/make of amplifier to buy.
I suggest some N-channel enhancement mode MOSFETs and some diodes. You need to provide the current rating of your actuator. Some resistors maybe 2Kohm never hurts for the MOSFET gates. The following is a good starting point:
https://secure.dipmicro.com/store/FQP50N06
The current rating is 50A. It's essentially a switch to turn on and off your actuator. You use arduino pin to switch it.
Tell us a bit more about the acutator? How much current (amps or milliamps) does it need? How fast (or how frequently) does it actuate?
Will I need an amplifier?
You generally need a relay, but most relays need more power than you can get directly from the Arduino too. So, you might need a transistor or MOSFET driving a relay, or you may be able to drive the actuator directly from a transistor or MOSFET.
I'm working on a project now that will use a solid state relay. The solid state relay can be driven directly by the Arduino, and it can switch faster than a mechanical relay (but not as fast as a MOSFET). However, they are usually more expensive and they don't operate as ideally as mechanical relays (there is a slight voltage drop when 'on' and some leakage when 'off').
It's a Framo-Morat mini linear actuator: Actuates slowly, and that is fine. Only needs to move about once every 10 minutes.
1000 N
24V
3.00 A
I plan on using a DC regulated power supplying box as the power source. From what I understand I would rather not use a relay because I would like to eventually use PWM to vary voltage, if that makes sense.
You can use the MOSFET in my reply. Depending on the actuator, you may or may not be able to use PWM to drive it. The spec sheet probably says yes/no on pwm.
liudr, correct me if I'm wrong, but the Mosfet you linked to isn't a logic level device, so the OP will need some additional circuitry.
John_S:
liudr, correct me if I'm wrong, but the Mosfet you linked to isn't a logic level device, so the OP will need some additional circuitry.
Not sure what logic level device means. I thought that part will do the switching. What additional circuitry do you suggest?
From the datasheet:
RDS(on) Static Drain-Source
VGS = 10 V, ID = 25 A -- 0.022 ? On-Resistance
It is quoted as requiring a VGS (gate voltage) of 10V to be fully saturated. Running it directly off an arduino pin (5V) will not turn it fully on and it will have higher resistance (and heat). It will switch the load without a problem, but it should be hooked up like this:
I see. I think you are right John. To get the maximal current you need to apply 10V Vgs, as in Figure 2. Transfer Characteristics. The current saturates above Vgs=10V. From the same figure, when Vgs=5V, you get around 10A current, over the 3A for the OP's actuator. So is it possible to just use it with arduino 5V pin for this type of load? I have not used this MOSFET before 
It might work just fine, but I'd be concerned about the mosfet not being saturated. When that happens there is a voltage across the Source and Drain (versus close to 0V when it's saturated). This makes the mosfet run hot and the load doesn't get the full voltage. The mosfet might have 4-5 volts across it (I just pulled that number out of a hat...), leaving 19-20V for the load. If that's the case, the mosfet will be dissipating 15W.
Also the Gate threshold voltage could be anywhere between 2.0 and 4.0 volts when it will pass 0.25ma. You might get a bummer at 3.99V, yet it's fully within specs. In this case 5V will not turn it on much at all.