I'd never use them under an insert, that's for sure.
I have used them in inserts. In my countdown the target inserts use a horizontal socket. Using the PBL new leds allowed a nice glow to these inserts. The 3 led ones didn't cut it.
On my Cleopatra right side outlanes, here too, horizontal sockets are used. (the left outs use vertical sockets) Putting the 4 led her worked great as well.
I am experimenting with making my own leds like these in the pic that will allow me to position leds better in the horizontal sockets. Use old bases and solder in my own leds on flexible buss wire leads.
FlexibleLEDPinball.jpg (Click image to enlarge)
And yes, as others have stated, they are very bright!
I also built a lamp/led test jig a while back. This allows me to compare different leds outside of the Pin. I have since added 555 base sockets as well. I did end up making the jig more compact and nicer looking.
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