Good evening!

I am quite new to electrical engineering but I am trying to help out a local fire department with a project. Here's the goal: whenever the sirens go off, turn on the lights in their bunk room. In the room, they have a device with a 6-pin DIN output that is energized only when an alert is received.

I found some socket adapters on Amazon for the 6-pin DIN, but would love a little bit more understanding of how I can use that to possibly activate a relay (or something) to turn on a full-sized light.

I know I am new so I really do appreciate the help! Please dumb things down if possible... I am still learning.

Project specifications: the room is pretty small, so they are hoping for one (maybe two) red light bulbs to activate whenever an alert comes in. They do not need the main lights in the room, as this would be a little to intense to wake them up. I really just need help figuring out how to connect the 6-pin DIN to a relay to activate these lights. I watched a YouTube tutorial on relays with Arduinos, and am wondering if this would be similar. The desired result would be a small box, with a light bulb or two on top that plugs into the DIN port on their pager system and lights up whenever the port is activated. My biggest question is: would there be an easy way for a Raspberry Pi to detect the change in state from the 6-pin DIN? I can figure it out from there.

Diagram of the PINS on the 6-pin DIN

  • \$\begingroup\$ The phrase "Relay Closure Timing" doesn't really convey much. Do you have any other details about what this device is -- perhaps a user manual, or at least a manufacturer and model number? My guess would be that you could use pins 2 and 3 to operate a power relay -- check them with an ohmmeter. \$\endgroup\$
    – Dave Tweed
    Jul 6, 2020 at 0:23
  • \$\begingroup\$ @DaveTweed manualslib.com/manual/1718313/… \$\endgroup\$ Jul 6, 2020 at 0:25
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    \$\begingroup\$ Are you looking to switch on the built-in room lighting? If so, you'll need to hire an electrician who can make sure that the modifications are up to code. Otherwise, if you just want to switch on a table lamp or something, you could do it as a plug-in DIY project, but only if you're comfortable with handling mains power. It doesn't sound like you're quite there yet. \$\endgroup\$
    – Dave Tweed
    Jul 6, 2020 at 0:38
  • \$\begingroup\$ Oliver, there are lots of questions in mind. How many people may be in the same room? The reason I ask is that this appears to be nothing more than a base charging station of sorts with a few added conveniences. If so, and if there may be more than one person in the bunk room, then you'd probably want the room lights on if anyone's radio gets an alert. So all of them would need to be wire-OR'd together, somehow. What's the full situation? Describe what is NOT desired as well as what IS desired. \$\endgroup\$
    – jonk
    Jul 6, 2020 at 2:57
  • \$\begingroup\$ @jonk I have edited the post with a "project specifications" section. \$\endgroup\$ Jul 6, 2020 at 11:49

1 Answer 1



simulate this circuit – Schematic created using CircuitLab

You don't need a Raspberry Pi for this, you don't need an Arduino for this, either.

Arduino and Raspberry would just add an unnecessary complexity to the circuit.

The alarm device already has a buit-in relay; but, it does allow maximum voltage of 28 VDC, maximum current of 750mA, and maximum power of 10W. If you want more power than this, you would need an additional relay - what wouldn't be complex to do, either.

Look at the device datasheet:

"When the accessory relay is energized, its contacts close and present a short across pins 2 and 3 of the connector. The relay contacts are rated for 10 watts maximum at 28 VDC/AC 10-watt rating the closed contacts can handle up to 750 mA continuously and switch up to 400 mA ofcurrent. Relay contact rating: 750 mA maximum @ 28 VDC."

You just need to use a charge that can be handled by this relay (750 mA @ 28 VDC), or just wire a power source and another relay to the pins 2 and 3, and the another relay would handle the charge that you need.

With maximum ratings of 10 W, 750 mA and 28 VDC, you can light up a board with red LEDs (and current limiting) enough to wake up everyone. I suggest you stay with 12V, there are plenty of options, with 12V and 750mA you can reach 9W, which can light red LED's VERY bright!

You could use an automotive red bulb (be sure that you use the ones with LEDs), they have built-in resistors, and a LED brake tail-light bulb would draw only about 500 mA at 12V There are plenty of options; search Ebay for "12v red led beacon".

  • \$\begingroup\$ I think you meant to put 28V supply instead of 12V? \$\endgroup\$
    – Leoman12
    Jul 6, 2020 at 13:48
  • \$\begingroup\$ No, I really intended to put the 12V supply, because it is a common value and there there hundreds of light fixtures rated at 12V. The maximum rating for the device's relay is 28 V, but, of course, you can connect a lower voltage. For a simple application like this, there's no need of 28V, which is not a common value. \$\endgroup\$
    – mguima
    Jul 6, 2020 at 13:59
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    \$\begingroup\$ @Leoman12 I edited the drawing for make it clearer. \$\endgroup\$
    – mguima
    Jul 6, 2020 at 14:06
  • \$\begingroup\$ Thank you so much for your answer. This looks great. Let’s say I did want to use a Pi to detect the alarm and send a signal to other lights and units via wifi throughout the station- how would I connect the alarm unit to the pi? Could I connect pin 2 or 3 directly to the Pi or would I need a specific circuit? \$\endgroup\$ Jul 6, 2020 at 19:55
  • \$\begingroup\$ @Oliver, if the answer was useful, it's usual that the person who asked the question marks it as accepted. You can detect the alarm only with Pi. Because the device's relay only short pin 2 to pin 3, you should connect device's pin 2 to 3.3V (3.3V is logical "high" for Pi; there's 3.3V available in pin 1 of Pi's header), and connect device's pin 3 to one of RaspPi's generic GPIO pins. So, the hardware is done; the next step is just writing the software that will sense when GPIO pin goes high and do whatever you want it to do (send email, write a log, change a webpage, etc). \$\endgroup\$
    – mguima
    Jul 6, 2020 at 21:33

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