56. Flashers and Strobes

Flashers and strobes are extra lights on your cab to reproduce the bright flashing light effects of the real machines. I personally rank flashers in the top tier of must-have feedback devices, as they add a huge amount of excitement and realism to the playing experience.
Pinball machines have always used blinking lights to attract players and add to the visual appeal of the game. The light shows became more sophisticated when software started controlling the games in the 1980s and 90s, as complex lighting patterns could be programmed and coordinated with the game action.
One of the key light show components in the 1980s and 90s machines is the "flasher" light. A flasher is a bright lamp in a plastic dome, usually situated above the playfield, maybe near a ramp or other vertical element sticking up out of the playfield. Games from the 80s and 90s typically have five or six flashers distributed around the playfield. As the name implies, flashers light up briefly at key times to create a brilliant strobe effect, to underscore an event in the game and add drama.
Flashers in real pinballs: alongside the right ramp in Earthshaker; behind Rudy in Funhouse
The flasher lights from the original games are, of course, reproduced on-screen in the Visual Pinball versions and other simulator versions. They appear in the video version just where they would have been on the real playfield, and they light up when they're supposed to. That's fine for desktop play, but when you blow it up to life size in a pin cab, it becomes more apparent that they're artificial; the video version just isn't as bright as the real thing.
That's why many pin cab builders include actual flasher lights on their cabs. Rather than relying entirely on the on-screen video renditions of the flashers, you can supplement the video display with a set of real flashers, which produce the same brilliant light as the real thing.
Related to the flashers is the "strobe" light. This is an embellishment thought up by the pin cab community, not something you find on real pinball machines (not commonly, anyway). It usually takes the form of a very bright white light somewhere in the player's line of sight. The DOF software will flash this briefly (thus the "strobe" monicker) at dramatic points in the game play. This might just seem like one more flasher light, and in broad terms, it is. The only reason for calling it out as a separate device is that it's usually implemented with a much brighter light source than the regular flashers, so that it produces a particularly dramatic burst of light at appropriate moments.

Flasher panels

In the real games, flashers are arranged around the playfield in different places in each game. There's obviously no way a virtual pin cab can reproduce the exact placement of the original flashers in every game (other than with the video renditions that we've already decided we want to supplement). We can't even move them around per game; we have to pick a fixed set of locations. So the usual arrangement is to group a set of flasher lights together in a "flasher panel", usually arranged in a straight line across the width of the cabinet.
There's no fixed rule about how many flashers you use or where to place them. It should go without saying, but it's your cab, so it's your call. But given the constraints, there are some common arrangements that most cab builders end up using. Let's look at the options.
Number of flashers: Most pin cab builders use a panel with three or five flashers.
What's magical about the numbers 3 and 5? History, mostly. The DOF Config Tool database has specific support for 3- and 5-flasher setups, because those are the most common setups that people build. (And now everyone goes with those setups because they're what's supported.) The 5-flasher setup also has a somewhat deeper significance in that it maps well to the original physical flasher layout in most real tables. Most of the 1980s and 90s machines used about five flashers total, so a 5-flasher panel lets DOF map the flasher effects from the original games directly to your physical lights.
You can build panels with any number of flashers you want, but a 3- or 5-flasher setup is easiest to work with because of the pre-programmed DOF support.
I'd recommend the 5-flasher setup if you're building a full-size cab, since it will easily fit and will produce the most interesting light show effects. The 3-flasher setup is mostly for mini-cabs where there's not room for five.
Placement: Once you have your panel of three or five flashers, the possibilities for where to situate it become fairly apparent based on the space available in your cabinet. The most common places are:
  • At the back edge of the playfield TV. This is the most common placement, because it answers the question "what should I do with the extra space behind my TV?" that most cab builders are faced with. Nearly all pinball cabinets designs (even the "widebody" plans) are longer and narrower than a standard 16:9 TV, so there's usually some extra front-to-back space to fill, typically between 3" and 6".

    You can position the panel so that it lies flat in the same plane as the TV, or you can tilt it up at an angle, if you left any vertical space between the playfield and the glass cover. My panel is tilted up at about a 30° angle to fill the vertical space (see the photo below).

  • Vertically, on the inside back wall of the cabinet above the TV. Some people prefer this arrangement because the lights point more directly at the player, which might slightly reduce reflections from the glass cover.
  • On the front of the backbox, in the speaker panel area just below the DMD. If you positioned your TV at the very top of the cabinet with no room between the TV and glass cover, you probably can't fit flashers inside the cabinet. You can position them outside the cabinet instead, on the front of the backbox.
  • Across the top of the backbox, near the front edge. I have an extra set of five flashers here on my cab. This is a good place for a supplemental set of flashers, but I wouldn't recommend it as the location for a lone set, since it's not in the player's line of sight. That greatly reduces the impact. It does add to the effect for bystanders, though, which is why I like it as a secondary location.
My flasher panel. Five flasher domes are distributed across the width of the cabinet. The panel is at the back of the playfield TV, tilted up at about a 30° angle to the plane of the TV, so that it fills both the horizontal and vertical gap at the back of the cabinet.

Building a flasher panel

LEDs: For the full effect, you'll want to use an RGB LED for the flashers. This allows the software to control the color emitted. An RGB LED has separate elements internally for red, green, and blue light (the "R", "G", and "B" of the name).
The type that most people use in pin cabs can be found on eBay by searching for "star base LED" or "3W LED RGB". They look like this:
The type on the left is the "star base" type. These come with a metal base that serves as a heat sink and makes the wiring a little easier. The type on the right is actually the same LED, just without the base. You can buy them either way. Most people think the type with the base is a little easier to work with.
These are sold in individual colors as well as RGB, so be sure to order specifically the RGB type. All of the parts I've seen for these on eBay are the same basic device, so there's not too much risk of finding a wrong part that looks similar, but here are the approximate electrical specs to look for just to be sure you have the right thing:
  • Red channel: 2.2 to 2.4V, about 400mA
  • Green channel: 3.2 to 3.4V, about 400mA
  • Blue channel: 3.2 to 3.4V, about 400mA
Plastic domes: Most pin cab builders use the same domes used on the real pinball machines for their flashers. They come in two main types, which are different only in how you attach them. Here are the Williams part numbers:
The screw tab type is a little easier to install; the twist-on type looks a little cleaner since the fasteners are hidden under the dome. You can easily make either type work as long as you plan for it.
The domes come in various colors (red, purple, amber, etc.), but for pin cab purposes, you almost always want the clear type, since we use them with color-changing RGB LEDs. If you want a particular color for some reason, the last two digits of the part numbers above are the color code for "clear", so you can find the other colors by searching for the part number prefix without the -13 suffix.
Voltage supply: Plan on supplying the flasher LEDs from a 5V power supply.
A lot of new cab builders find LED voltage specs confusing. LEDs always quote a "forward voltage", and it's always something weird like 2.2V or 3.4V. And it's usually a range, like 2.2-2.4V. Does this mean that you're supposed to find a 2.2V power supply? Fortunately not! The "forward voltage" for an LED isn't the supply voltage required. It's the amount of voltage that the LED "drops" when operating, which is sort of the amount it uses or consumes. That's why it's often quoted as a range; the manufacturer is just saying that the exact number varies a little bit from one individual part to the next, but it should always be in this range, and will usually gravitate to the middle of the range. What does this mean for the supply voltage, then? It's really simple: the supply voltage can be any voltage higher than the forward voltage. So if the forward voltage is "3.2-3.4V", it means that you can use pretty much anything higher than 3.4V. It's best to pick the lowest conveniently available voltage higher than the required minimum, because the higher the voltage, the more energy will get burned up in heating the resistors. In a pin cab, you usually have a 5V supply readily available, (see Power Supplies for Feedback), so 5V is the best option for almost every LED. If you had a 4V supply or a 3.7V supply, that would be better still, but those aren't typical voltages in a pin cab; 5V is what we usually have readily at hand.
You might read advice on the forums to use a 12V power supply for the flasher LEDs. Ignore that. It's best to use the lowest conveniently available supply voltage above the LED's "forward voltage" spec. Using a 12V supply just burns up all of the extra voltage in resistor heating, which forces you to use physically larger resistors that can tolerate all of the extra waste heat. A 5V supply lets you use smaller resistors that waste less energy.
Resistors: The star base LEDs are bare LEDs that do not include any sort of built-in current regulation. This means that you must include separate resistors in the circuits when wiring them.
It's important to choose the correct type of resistor for each color channel. LED Resistors explains how to choose, and includes a calculator to determine the correct Ohms and Watts value for each.
The resistors have to be wired into the circuit in series with the LED. They can go on the (+) side or the (-) side; it's exactly the same either way.
You can wire the resistor for the LED on the negative side or positive side, whichever is more convenient for your setup. It's the same electrically either way.
The red, green, and blue channels are independent devices, so each channel needs its own resistor. The channels will have different resistance values, too; that's why they quote the "forward current" and "forward voltage" separately for each color.
Pay attention to the wattage value that the resistor calculator reports, and be sure you buy resistors with at least the required wattage. This is not some kind of "detail for nerds" that you can ignore; it's part of the spec for what you need to buy.
Here's a simple circuit board design for the resistor panel. This is designed to be used with a ribbon cable connector to the output controller board. The pin layout of the 16-pin connector (at the bottom of the board as pictured below) matches the pin layout of the Pinscape expansion board RGB Flasher connector, so you can conveniently connect this directly to the expansion board with a ribbon cable. You can also easily use this board with non-Pinscape output controllers; you just have to program the controller so that the LED channels match the pins on the connector.
Here are the EAGLE plans, if you want to have this board manufactured:
mjrnet.org/pinscape/downloads/flasher-resistor-board.zip
You can have it made in lots of three by OSH Park for about $16, with an extremely simple ordering process (just upload the .BRD file from the ZIP above). You can have it made more cheaply per board at PCB makers like Elecrow, but they have larger minimum order sizes and require you to generate Gerber files. That procedure is explained in Fabricating the Expansion Boards.
To assemble this board:
  • Install a 2x8-pin 0.1" pin header as shown in the picture
  • If you use a shrouded header for the 2x8 connector, make the sure the keying slot on the shroud is aligned properly for your ribbon cable; see 0.1" Pin Headers
  • Figure the resistor values required as explained in LED Resistors
  • Be sure to pay attention to the wattage calculation in that section, and use resistors with at least the required wattage specs
  • The board is designed for resistors up to 4mm in diameter and up to 12mm in length (the gigantic squarish "cement" resistors won't fit)
  • Install the resistors in the R_xx slots: R_1R is the resistor for LED 1 RED channel, R_2B is LED 2 BLUE, etc
  • Resistors aren't polarized, so it doesn't matter which direction you install them
  • I'd solder hookup wires from the boards to the LEDs directly to the edge connector terminals; 1R is for LED 1 RED, 2B is LED 2 BLUE, etc
  • If you prefer, you can install single-row 0.1" pin headers on the edge connectors, but I don't think that's necessary in this case, because I'd consider this board to be an integral part of the flasher board that can be hard-wired to the LEDs
  • If you're using the Pinscape expansion boards, simply connect the resistor board to the RGB Flashers header using a 16-conductor ribbon cable with a 16-pin IDC plug at each end; see Ribbon Cables for help building these cables
  • When plugging in the cable, be sure that the ribbon cable is oriented so that Pin 1 on the expansion board connects to Pin 1 on the resistor board (Pin 1 on both boards is marked by the little triangular arrow next to the header)
Building the panel: I went with a simple design for my panel.
  • I started with a piece of 3/8" plywood, cut to the inside width of my cabinet and a height that I measured to fit the available space where I planned to install it.
  • I drilled five 1/2" holes at regular intervals, where I wanted to place the lights.
  • I soldered four wires to each of the five star LEDs: one wire to each of Red(-), Blue(-), and Green(-), and a fourth wire that I connected to all of the (+) terminals. As described in Feedback Device Wiring, the standard wiring plan for all devices is to switch on the (-) side, so the (+) side is always connected directly to power and can thus be daisy-chained across all devices that share the same voltage.
  • I then installed the LEDs in the pre-drilled holes, holding them in place with little metal clamps. The clamps aren't anything standard; they're just something that I made custom by cutting them out from a piece of sheet metal from Home Depot.
  • I ran the wires from the LEDs to a small circuit board containing the resistors (see above). This is just an ad hoc circuit board I made for the cab. You can just wire the resistors in-line through the wires without a circuit board if you find that easier.
  • On the front side of the board, I attached the plastic dome with wood screws.
Finishes for the panel: Most people just paint their panels in the same color as the inside cab walls, usually black. I used custom-printed adhesive decals that I had made at the same time as the decals for the exterior of my cab. See Cabinet Art.
Heat sinks: Some people use large heat sinks with these LEDs. I don't personally think it's worth the trouble, because flashers are activated intermittently, for brief periods. Plus, the metallic star bases already provide a moderate degree of heat dissipation. If you were leaving these LEDs on at full power for long periods, heat sinks would be warranted, but they're not necessary in this application.
If you want to use heat sinks anyway, you can find a variety of suitable products on eBay. Attach them to the back of the star base with thermal paste.
Wiring to the output controller: Follow the general plan in Feedback Device Wiring to connect the LEDs to your output controller. Connect the (+) side of each LED to the +5V from your power supply, and connect the (-) side to an available port on your output controller. Keep in mind that each channel requires a resistor (see above) in series with the LED, inserted either between +5V and the LED (+) terminal, or between the output controller port and the LED (-) terminal.
The DOF Config Tool requires that you use consecutively numbered output ports for each Red-Green-Blue group, in that order. For example, if you wire the RED channel of Flasher #1 to output port #8, you must wire GREEN to port #9 and BLUE to port #10.
DOF setup: In the DOF Config Tool, after you've done the basic setup for your output controller, go to your Port Assignments page. For each flasher LED in your setup, find the port number for that device's RED channel, and set it to the appropriate flasher device:
  • For a 5-Flasher setup, the flashers are labeled, from left to right, "5 Flasher Outside Left", "5 Flasher Left", "5 Flasher Center", "5 Flasher Right", and "5 Flasher Outside Right".
  • For a 3-Flasher setup, the flashers are labeled, from left to right, "3 Flasher Left", "3 Flasher Center", and "3 Flasher Right".
When you select the appropriate "5 Flasher" or "3 Flasher" device for the RED channel's port, the Config Tool will automatically assign the next two output ports in sequence to the GREEN and BLUE channels for the same device. This is why you had to physically wire each LED to three consecutively numbered ports in Red-Green-Blue order. It's just the way the Config Tool thinks about RGB, so you have to do the wiring to match its expectations.
Pinscape expansion boards: If you using the Pinscape expansion boards, you should connect the flashers to the dedicated Flasher outputs on the main board. These outputs have enough power handling capacity for about three sets of flashers in parallel, if you have multiple sets (such as my arrangement with the main flasher panel at the back of the cabinet, plus a second set on top of the backbox).

Strobes

Strobes make a nice accompaniment to flashers. Strobes are simply bright white lights, usually much brighter than the flasher lights, that the software can light up occasionally for particularly dramatic events in the game.
Unlike flashers, strobes are typically monochrome, not RGB. They're just plain white lights. This makes them a little quicker and easier to set up since you only need a single output port to control them.
One question that new cab builders always ask is whether you need some kind of special timed bulb that handles the rapid flashing effect. The name "strobe" certainly suggests this. The answer is no: the flashing effect is handled entirely by the DOF software. All you need for the physical device is a bright white LED.
Parts: The device that most pin cab builders use for strobes are small but bright LED panels designed for automotive use (emergency lighting, spotlights, etc). They can be found on eBay by searching for 22 LED white strobe. (This search might also turn up some "22 Inch" LED light bars for trucks. Ignore those. You're looking for the smaller "22 LED" products.) The ones you're looking for look like this:
Since these are designed to be installed in cars and trucks, they usually come with a separate control box, which lets you blink the lights in various flashing patterns. You don't need these control boxes for DOF - just discard the control box and plug the LED directly into your output controller. That will let DOF control the flashing effects directly. (This also means it's perfectly fine to use an LED that doesn't come with any sort of control box.)
Positioning: A lot of people put a pair of the 22-LED strobes on their flasher panel, usually one at each outside edge. Others put them on top of the backbox or in the speaker panel area.
I put mine on top of the backbox, facing forward (facing the player). I'm happier with that location than in the main flasher panel because I find them too bright to have directly in your line of sight while playing. Having them on top of the backbox makes the strobe effect suitably dramatic without blinding the player every time they fire.
Power supply: Check the specs on your specific product to be sure, but the standard power requirement for strobe panels like the ones described above is 12V DC. The same is true for almost anything made for automotive use, since that's the standard car "cigarette lighter" voltage.
LED resistors: Not needed for the typical 22-LED panel. These are meant to be plugged directly into a car's 12V power supply, so they have the necessary resistors built in.
Wiring: Follow the basic wiring plan in Feedback Device Wiring:
  • Connect the 22-LED panel's (+) terminal (usually the red wire) to the +12V power supply (the yellow wire from your secondary ATX power supply)
  • Connect the LED panel's (-) terminal (usually the black wire) to an available port on your output controller
  • If you bought one of the car-and-truck strobes that comes with a blinker control box, discard the control box and connect the wires from the LED panel directly to your output controller (LedWiz/Pinscape/etc). DOF will handle the flashing effects, so you don't need any separate blinker control box; including it in the circuit will just interfere with the wider range of effects DOF can create.
No additional parts are needed with these (in particular, no resistors are needed).
The typical 22-LED panels require about 500mA. This is just barely within the safe range for an LedWiz output, so you can connect it directly to an LedWiz. Don't connect two panels in parallel to the same LedWiz port, though, as this would require 1000mA, which is double the LedWiz's safe limit.
Pinscape expansion boards: You can connect a 22-LED panel to the dedicated "Strobe" output, to any RGB Flasher port, or to a power board port. Any of these ports will handle two of the 22-LED panels wired in parallel.
DOF setup: In the DOF Config Tool, go to your Port Assignments page. Find the output controller port number where you wired the strobes. Assign this to "Strobe".