Greetings everyone! I need help on deciding which component I can use to control 24VDC LED Tower Lights. This lights will blink during certain moments of the application I intend to use them for. I am not sure to use a MOSFET module, Solid State Relays or normal Relays in order to control these lights! Please let me know your recommendations!
It is customary (and necessary) to include the current requirement (mA/A) of your application.
In addition it is customary to post a vendor link for the device you are using.
Hello! I am using 24V LED Tower lights by Auer. They consume about 22mA-33mA.
You didn't specify AC or DC.
I don't see a wiring diagram. Please post one if available or a photo of the actual terminals.
I don't see your device model/part number in your post.
As a general rule , it is standard procedure to use opto-couplers to isolate a microcontroller
from voltages that could damage it.
The load is connected to +24V at one end and the other end connected to the collector of the
opto coupler.
The input led of the optocoupler requires a current limiting resistor which is calculated by:
Vcc/led Vf
Typically 20 - 30mA , so
5V/0.025 = 200 ohms
DC voltage.
This is the only diagram I found, the base comes pre-wired. https://www.auersignal.com/site/pim/media/95a70613-df6a-4b84-b87b-635c56391d10.pdf
Thank you for your information. Just to clear things up, the optocoupler is to protect the Arduino, but what do I use to control the lights? MOSFET, relay or SSR?
optocoupler is to protect the Arduino, but what do I use to control the lights? MOSFET, relay or SSR?
The optocoupler IS the control device.
It protects the arduino because the INPUT is separated from the OUTPUT by a 5000V ISOLATION BARRIER.
Interesting, I am assuming 24V DC, Use a logic level avalanche rated MOSFET rated at about 50 Volts or greater. IRLZ44N is a good part if it will do what you want. you can find the data sheet here: http://www.irf.com/product-info/datasheets/data/irlz44n.pdf. You can hook the gate to the arduino with a 22 Ohm or less resistor, a direct connection would work just as well. Be sure you connect all the grounds together including the source of the MOSFET, Best to make this connection at the power supply to keep the switching noise off the arduino. The ground of the arduino will also connect at the power supply. To use only the 24V power supply you will need to add a buck converter in the circuit to drop the 24V to approximately 8 Volts. As far as the LEDs you can use series parallel configurations if they are not rated at 24 Volts. This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil
DC voltage.
That means the COMMON needs to connect to the 24V GND and the optocouplers will need to switch each
color by inserting the opto transistor between the 24V and the COLOR terminal in a HIGH SIDE
configuration. (HIGH SIDE means the switching device separates the power source from the load.
LOW SIDE means the switching device separates the load from GND.
ie:
opto COLLECTOR =>24V
opto EMITTER => LEVEL-1 /LEVEL-2/LEVEL-3/LEVEL-4 terminal.
With no input the color is OFF.
With a logic HIGH on the input , the transistor turns on , connecting the 24Vdc to that color terminal.
The COMMON is the 24V GND.
FYI, there are two schools of thought, mosfet or optocoupler.
What are the differences ?
If the mosfet shorts out there is a current path from the 24V back to the arduino through the gate.
With an opto, there is NO current path from the 24V to the arduino because it is isolated by a 5000V
ISOLATION BARRIER.
Since the DAWN of the COMPUTER AGE, ALL professional industrial equipment has used opto isolation
to protect the computers because if the computer gets fried it takes a lot longer to get things working
again than if a single device gets damaged.
With an opto , EVEN if the transistor got shorted, the arduino is safe from the 24V.
22-33mA is a lot of current, too much even for most optocouplers to handle directly; you still need additional circuitry (MOSFET or so) to switch the load.
Just use a logic level MOSFET. It's the normal way of switching higher voltages with an Arduino, including 24V loads. For these low currents a good old NPN transistor will do just fine as well.
Collector current: 50mA !
RTDDS (ReadTheDamnDataSheet)
wvmarle:
22-33mA is a lot of current, too much even for most optocouplers to handle directly; you still need additional circuitry (MOSFET or so) to switch the load.Just use a logic level MOSFET. It's the normal way of switching higher voltages with an Arduino, including 24V loads. For these low currents a good old NPN transistor will do just fine as well.
So an IRF520 MOSFET will work fine for the application? One for each lamp of course.
I don't think you understand.
The lights are already connected to GND.
That means in order to switch them you have to switch 24V to the terminals in the diagram.
That's called HIGH SIDE SWITCHING.
That requires P-CHANNEL MOSFETS (NOT N-CHANNEL)
As mentioned, you could use a general purpose small signal transistor like an 2n2222, 2n3904, 2n3906,
etc.
If you don't know how to wire it up Google "Mosfet high side switch"
What happens if I use relays or SSRs?
Other than that you spend way more money and end up with a much more bulky and somewhat complex end product (your relay needs its own 5V supply, can't power it off the Arduino), it will work pretty much the same way.