Fasten Seatbelt Sign NS/FSB

[wispy skiff]

Hi, I have bought an original No smoking and Seatbelt sign on ebay. https://www.ebay.com/itm/192962565074
Which I would like to wire up and use with mobiflight.
It uses 12V as power, can I use the Vin pin on my arduino mega or do I need to buy a seperate power supply? I have read somewhere that the Vpin have a max voltage of 20V sometimes. Don't want too high voltage.
My initial thought was to wire the sign directly to the toggle switches. So having 2 wires on the toggle switch. One to the arduino and one to the sign. Also having the ground wire connected to the arduino.

What would be the best way to make it work?
Thanks in advance

[sweet glade]

I don't recommend you use the Vin pin. That is intended to power the Arduino from an external power supply.
Since your lights are 12v, use an external 12v power supply with a FET transistor controlled by an Arduino pin. One FET for each sign.
Alternatively, if the lights are leds, just connect the lights to the arduino directly. They will probably work with 5v, just a bit dim.

If they are leds, you could try downsizing the current limiting resistors so they work with 5v instead.

[pallid orbit]

@dapper harness you did this, maybe you have some useful tips?

@wispy skiff but the VIN is basically the input raw voltage of the Arduino - as you can power it from the round power jack connector. If you power it from USB, it is going to be 5V.

The problem is the arduino pin gives you 5V but it is not designed to power things like a lamp, it will burn the Arduino's processor.

Arduino data pins can be used for logic control, so you can connect a relay to it, that in turn is connected to a 12V power supply that turns on the lamp when the Arduino data pin is at 5V.

OBVIOUSLY do not use a mains plug to power your sign, this image was found from the net

but put your 12V power supply in place of that power plug

that also has a motion sensor wired to it but ignore that part

so you connect your arduino GND, 5V and the "LED Output" pin to the relay

and if you turn on the led in mobiflight, it should click and make a connection

and then wire the +12V wire through the relay pins to the lamp, and wire lamp GND to GND of the power supply.

You also want to connect the power supply ground to the arduino ground.

[dapper harness]

so mine seems to have a stepdown regulator so applying direct 5v from an arduino pin to mine makes them just as bright as applying 12v

[pallid orbit]

it sounds like it might pull quite a lot of current for an IO pin though, might want to measure it

[wispy skiff]

Okay, thank you guys for the help. My friend also recommended me buying a stepdown regulator. Will try this when I recieve the sign, hopefully it will be delivered tommorow