Grounding 24v Signal Tower with Digital Pins

Please forgive my lack of electrical understanding...

I'm trying to control a Patlite LR4 LED Signal Tower using an Arduino Mega. The wiring for the Patlite has one 24v power supply wire, and a wire for each LED. To control the LEDs, I am supposed to connect it to a 24v power supply and ground each wire when I want it to turn on. I am wondering if I can ground and control the LEDs to the digital pins on the arduino using the digitalWrite() function. I know that I can use relays to control the LEDs but I would like to know if I can do it straight from the digital pins.

I am supposed to demonstrate this signal tower tomorrow and my biggest concern is frying the Arduino and not having enough time to buy another. I apologize if this is an elementary level question, or if it does not make sense. I am a programmer, not electrician.

Thank you for your input.

You are correct that the Arduino can't handle the voltage or current and it could be fried if you connect it directly.

You need a transistor driver or MOSFET Driver circuit. (You can leave-out the diode since you have a non-inductive load.)

Check the current rating on the lamps (Amps or milliamps). Any transistor or MOSFET will handle the voltage, but make sure it can handle the current and give yourself plenty of "safety margin".

Alternatively, you can get a relay board with built-in relay drivers. (Most relay coils also require more current than the Arduino can directly-supply so they need a driver too.)

Or, you can use a solid state relay which can be driven directly from the Arduino. But, make sure it's for switching DC. AC solid state relays are usually made with TRIACS and with DC you can switch them on, but they never turn-off until power is turned-off (or until the next AC zero-crossing).

my biggest concern is frying the Arduino and not having enough time to buy another

Presumably this is an "industrial application" so it needs to be maintainable. I'd recommend that you get a spare Arduino and program it so it's ready to plug-in. Also build a spare driver boards/circuits and design them to plug-in so you don't have to fool-around soldering in a panic situation.

Thank you very much for your response!

willocov:
Please forgive my lack of electrical understanding...

I'm trying to control a Patlite LR4 LED Signal Tower using an Arduino Mega. The wiring for the Patlite has one 24v power supply wire, and a wire for each LED. To control the LEDs, I am supposed to connect it to a 24v power supply and ground each wire when I want it to turn on. I am wondering if I can ground and control the LEDs to the digital pins on the arduino using the digitalWrite() function. I know that I can use relays to control the LEDs but I would like to know if I can do it straight from the digital pins.

I am supposed to demonstrate this signal tower tomorrow and my biggest concern is frying the Arduino and not having enough time to buy another. I apologize if this is an elementary level question, or if it does not make sense. I am a programmer, not electrician.

Thank you for your input.

You must use some type of transistor to actually turn the light on and off because 24 volts is way beyond what an Arduino pin can stand. Moreover, you are switching current, so some other device must be used.

Measure the voltage on the lead that you ground and you should find +24 volts, if I understand the light.

Paul