That is true, except for the Gottlieb EMs. On those games, they used a different socket that sits farther inside the drilled hole, so that the round globe of the #455 bulb ends up above the wood face of the insert when the bulb is in the socket.

In other words, if you put a #44 or #47 bulb in a Gottlieb socket, and the lamp sticks out farther than the other lamps, it means that socket is supposed to have a #455 bulb in it.

- TimMe

Just to clarify the pinwiki language a bit, the #455 lamp is in series with the relay coil itself, via the relay coil lock-in switch. When the the bulb blinks off the first time, the power to the coil is interrupted, and the relay drops open. So the relay pulls in and stays energized for the length of time it takes for the lamp to blink out for the first time, usually just one or two seconds.

As was already mentioned, on a Bally game this is all wired into the regular 50 VAC circuit for the coils. The resistance of the relay coil is chosen to act as a current limiting resistor for the #455 lamp so that the lamp doesn't blow out, although the lamp is definitely running hotter than normal.

An LED blinker lamp will not work in this circuit. For one thing, an LED blinker does not work by interrupting the circuit, so the coil would never release. And in any case, I have to guess that it is very likely an LED blinker lamp would quickly be fried in this circuit due to the high voltages and high currents involved.

- TimMe