57. Beacons

In virtual pin cab parlance, a beacon is a rotating or flashing light like you'd find on a police car or ambulance. Beacons make good backbox toppers, since they're the right size, and they can play an active role in the light show. They're also a good simulation feature, since lots of real pinball machines featured beacon topers.
Parts: The only part needed is the beacon itself, which you can buy as a ready-made product. I haven't seen any good DIY designs, probably because it's pretty easy to find off-the-shelf products that fill the bill.
The thing to look for is "police beacon" or "rotating beacon light". You can look for these on Amazon or eBay, but unlike most product categories, neither site tends to have very good options. The ones you'll find on either site are mostly "disco" or "party" lights - novelty toys, which won't be very bright or realistic. So instead of looking at a general retailer, you might try specialty automotive supply stores, such as Vehicle Safety Supply.
A particularly good option that I've found is the Peterson 771 series. I use a pair of these on my cab. They're inexpensive (about $25 apiece), they're exactly the right size and shape, they feature a traditional motorized rotating light with directional reflector, and they're available with red, blue, or amber lenses. They're a perfect fit for this job. To find them, search on the Web for Peterson V771A for amber, V771B for blue, and V771R for red.
Another option is the very similar looking Wolo Manufacturing 3100 series: 3100-A (amber), 3105-B (blue), 3110-R (red). I haven't seen these in person, but from the pictures and specs, they look essentially identical to the Peterson V771 series. They might even be the same thing under a different brand name. Current prices are about $20 per unit.
Beacons mounted on my cab's backbox, one red and one blue. These are off-the-shelf items, Peterson model 771, available from automotive supply sites.
Mounting: Many of the beacons you'll find (including the Peterson 771) come with magnetic bases that are intended to hold the light to the roof of a car. You'll probably want to remove the magnetic base and attach the light to the top of your backbox with screws or other wood fasteners. You could alternatively glue them in place, although I try to avoid glue as it can't be easily removed if you ever need to replace the device.
Wiring: Check with your product's documentation to be sure, but anything automotive generally runs on 12V DC. That works well in a pin cab because we usually have a 12V supply available from a secondary ATX power supply; see Power Supplies for Feedback for more on that.
Follow the generic wiring plan in Feedback Device Wiring:
  • If your beacon has a motor, be sure to connect a diode between the (+) and (-) leads of the beacon, with the striped side of the diode connected to the (+) lead of the beacon, as described in Coil Diodes. This is required if there's any sort of motor or coil in the device. Any beacon with a rotating light has a motor inside to drive the rotation.
  • Connect +12V from your power supply (the yellow wire for an ATX power supply) to the (+) terminal of the beacon
  • Connect the (-) terminal of the beacon to an available output port on your output controller
The beacon might not have specific (+) and (-) terminals. If not, the order of the connections probably doesn't matter.
Electrical interference: If you're using a mechanical beacon with a motor that drives the rotating light, be sure to use a diode as mentioned above. If you still have problems with electrical interference when it runs (for example, USB devices randomly disconnect, or you see random keyboard input on the PC), you might need to add more filtering. The two-inductor filter described for the shaker should work here. See "Electrical Interference" in Shaker motors for the wiring and parts details.
Check the power: You should check your beacon's power usage to make sure that your output controller can handle the load. The beacons I use draw about 500mA each, so the pair of them requires about 1A. If your product's documentation doesn't specify the power draw, you can test it yourself using an ammeter.
For Pinscape expansion boards: It should be safe to connect any beacon to any MOSFET Power Board output. Those outputs can handle up to about 4A. Nearly any beacon should be well under 1A. It's best to check (measuring with an ammeter if necessary) if you're not sure, though.
If you're using an LedWiz: It's safe to connect a beacon directly to an LedWiz output if the device draws less than 500mA. If it's above 500mA, you'll need some sort of "booster". See "Power Limits" in LedWiz Setup.
DOF setup: In the DOF Config Tool, go to your Port Assignments page. Find the output controller port number where you wired the beacon. Assign this to "Beacon".
Increasing the brightness: Most of the rotating light beacons you'll find come with small incandescent bulbs. If your cab includes flashers and strobes, the beacons might look dim and unimpressive in comparison. This isn't really the beacons' fault; it's more that the LED devices we use for flashers and strobes are extremely bright. They'll put a little incandescent bulb to shame (especially with the darkly tinted plastic dome covering it).
You can increase the brightness somewhat by installing an LED bulb in place of the incandescent that your beacon comes with. Most of the beacons use common automotive bulb types for which LED replacements are readily available. Almost all automotive light bulbs run on 12VDC, so the main trick is to figure out the type of socket base that your beacon uses, so that you can find a bulb that fits. Check your beacon's instructions, or just look at the bulb itself. The bulb type is often printed or embossed somewhere on the metal base of the bulb.
The Peterson model 771 beacons use bulbs with socket type 1156, also known as BA15S. Any LED replacement bulb with the same base and a 12V supply voltage should work.
In case you were wondering, you don't have to add extra resistors if you switch to LED bulbs. If you've read the chapter on LED Resistors, you know that "bare" LEDs require resistors in the circuit to limit the power going through them. But we're not talking about bare LEDs here; we're talking about LED replacements for incandescent bulbs. Any LED bulb that's designed as a plug-in replacement for an incandescent bulb has the necessary resistors built in, so no external resistors are needed.
If you install an LED, and the motor runs but the LED won't light up, you might need to reverse the polarity of the power supply connection to the beacon. Incandescent bulbs aren't polarized, but LEDs are. If the LED bulb won't light, try swapping the (+) and (-) leads connected to the beacon. This might also have the effect of reversing the direction of the motor, but it should make the LED light up. Warning: if you've attached a diode to the beacon (required if your beacon has a motor), be sure to reverse the diode at the same time that you reverse the voltage polarity.
Another thing you can do to improve the apparent brightness of the beacons is to supplement the beacons with some additional red and/or blue strobe lights. The "22-LED strobes" recommended in Flashers and Strobes also come in red and blue varieties. So:
  • Buy a 22-LED blue or red strobe, matching the color(s) of your beacon(s)
  • Mount it on top of your cab next to or behind the beacon, facing the ceiling
  • Unlike the advice for strobes in Flashers and Strobes, do use the little control box that comes with the strobe panel, so that the LEDs flash when the beacon is activated rather than turning on continuously.
  • Wire the control box to the same output port as the beacon, so that the LEDs start flashing whenever the beacon is running
  • Make sure that the added power of the LED panel doesn't overload your output controller port. If the combined load would be too great, use a second port for the strobe panel instead, assigning it in the DOF configuration to the same "Beacon" device.
The added LED panel obviously won't increase the actual brightness of your beacon, but it will increase the overall amount of flashing red or blue light during a beacon display, which will create the impression of a brighter beacon. I recommend this approach because I use something like it myself to good effect. (My setup is a little more custom, but it's basically the same idea. I use some extra LEDs around the perimeter of my custom fan housing instead of the 22-LED panels, and I use a custom-programmed flashing pattern controlled by a Teensy microcontroller.)