This information was originally posted by our member tomdotcom:
1. Frosted 44/555 - Single LED's - I typically use frosted tip single LED's for the backbox GI. The frosted tips tend to diffuse the light fairly well and they aren't overpowering behind the translite. Typically you have a choice between cool white and warm white for the bulb color. Cool white seems to look the best when the colors being illuminated are primarily blue, green, purple, white, black, and gray. Warm white seems to look the best when the colors being illuminated are yellow, orange, and red. In some situations you can use colored LED's to emphasize specific areas of the translite. For example, you could use colored LED's behind a pair of eyes on the translite to make them stand out or glow a different color. You can also use color changing LED's in certain situations, but it really depends on the effect you want to achieve.
2. 3-LED 44/555 (Pinball Life) - I've used the white 3-LED bulbs from Pinball Life on a few occasions and they work fairly well. They can sometimes be overpowering though, and in some cases they will create white circles of light behind the translite because they are so bright.
Frosted 44/555 - Single LED's or 3-LED 44/555 bulbs - Both bulb types work well in the playfield GI and it usually comes down to preference. The 3-LED bulbs can sometimes be too bright in certain areas where the bulb is visibly exposed. I've experimented with several different combinations and the one that works the best (in my opinion) is single LED frosted tip bulbs under the slings and ball return guides, as well as any other area where the bulb is visible to the eye. I then use 3 LED bulbs or single LED bulbs in the other GI areas. The single bulbs work well in most cases, but sometimes the 3 LED bulbs provide a little more brightness under dark plastics or in larger spaces with only a few GI bulbs to light the area. Cool white seems to look the best when the playfield and plastic colors being illuminated are primarily blue, green, purple, white, black, and gray. Warm white seems to look the best when the colors being illuminated are yellow, orange, and red.
1. 5 Matrix 555/44 bulbs - Normal 44 or 555 bulbs don't work well at all in spot lights because the light from the bulb shoots straight ahead. 5 matrix bulbs have a single LED that shoots straight ahead and then 4 LED's on each side of the bulb that shoot light out the sides. The light that shoots out the sides is collected by the reflective spotlight cone and is directed toward the target like a normal incandescent bulb would do inside the spotlight.
2. Wide angle LED's (30 degree or greater) - 5 Matrix bulbs can be a little pricey, so a solid substitute is to use a wide angle 44/555 LED (30 degrees or greater). The single LED wide angle bulbs do not generate as much light as the 5 matrix bulbs, but they work well in certain situations where you don't necessarily need to create a lot of light and only need to throw some color on an object.
Inserts can vary by size, shape, and color. The angle of the lamp socket under each insert can also vary quite a bit. Sometimes the bulb will be angled directly at the insert and sometimes they are parallel to the insert. The type of LED to use really varies by the combination of these factors and what will deliver the best result. So, I've listed the most common combinations below with recommendations for each one.
Clear White/Yellow inserts - Lamp angle is directed at the insert (not parallel):
White 44/555 Single LED Frosted Tip Bulbs - Clear white and yellow inserts can shine very intensely if a 3 LED bulb is used. The brightness isn't bad if there are only a couple clear white or yellow inserts, but the intensity and brightness can be very overwhelming if the playfield has a lot of these inserts and 3 LED bulbs are used. Single white frosted tip bulbs work a lot better in my opinion because they deliver good brightness but do not shine too bright to overpower the insert and blind the player.
Milky White or Milky Yellow inserts - Lamp angle is directed at the insert (not parallel):
White 44/555 3-LED or Single-LED frosted tip - If the insert is milky (not clear), then a 3 LED bulb or single LED bulb can be used. The haziness of the insert will help control the brightness from a 3-LED bulb so you can use either type. I typically use 3 LED bulbs for the larger inserts and single LED bulbs for the smaller inserts.
Red/Green/Blue/Purple/Orange inserts - Lamp angle is directed at the insert (not parallel):
White or Color matched 44/555 3-LED or Single-LED frosted tip - You can use white bulbs under the colored inserts and get good results, but color matching the LED to the insert will give a deeper color and better effect. Using all white is easier and makes ordering a lot more simple, but color matching does look nice. I typically use 3 LED bulbs for the larger inserts and single LED bulbs for the smaller inserts.
All inserts where the lamp angle is parallel to the insert:
Wide angle LED (Concave Lens) 44/555 or 5 Matrix LED - If the lamp angle is parallel to the insert, then you need a bulb that throws the light out the side of the bulb. I typically use a wide angle bulb if the insert is small and I use 5-matrix bulbs if the insert is large. You can color match the insert to the bulb color, but white seems to deliver the brightest results.
Some flashers are directional (all the light is angled straight away from the top of the bulb) and some flashers have bulbs on the top and sides of the bulb. Most flasher applications can use the straight away flasher because the bulb will be angled into a flasher lens cap or toward the insert or translite. However, sometimes you may need to use a flasher that has LED's on the side because the flasher will lay parallel to the insert or under a plastic and you need the light to shoot in all directions.
I usually color match my flashers to the insert color or lens cap, and I sometimes color match them to the playfield area or plastic covering. You can also use colored flashers under white inserts to add different effects.
44/555 Wide Angle or 5 Matrix LED - I usually try and color match the LED to the pop bumper. White LED's tend to shine through fairly easily and you can tell that the light is white versus the actual color of the pop cap. If you do decide to use a 5 matrix bulb, then be sure you have enough clearance on the pop cap. Some caps are shallow and don't provide a lot of clearance room for the taller 5 matrix bulb. The wide angle bulbs are shorter and should be used if you don't have enough clearance for the 5 matrix bulbs.
Nobody likes everything the same way. Hopefully this will help you in deciding how to use LED technology to improve your machine in your own style.