The electrical emitter is a device of varying design that emits electricity. In gameplay, this machine will unleash rays of electricity in an horizontal direction or vertical every few seconds. Should the playable character touch these rays, they will take damage. However, a Lightning Shield will allow the player to walk on top of electrical emitters without getting hurt.
Sonic the Hedgehog (16-bit)
Sonic the Hedgehog (8-bit)
In Sonic the Hedgehog (8-bit), electrical emitters appear in Scrap Brain Zone. In this game, they behave in the same way as their 16-bit counterparts. However, the orbs on the electrical emitters are yellow instead of pink.
Sonic the Hedgehog CD
In Sonic the Hedgehog CD, electrical emitters appear in the Wacky Workbench. In this game, they are small electric cubes (whose color varies depending on the time). In gameplay, they only fire one line of electricity at a time. To avoid them, the playable character must hang onto a pole and pass over them. Notably, in the good future, they are temporarily disabled at times.
SegaSonic the Hedgehog
Sonic the Hedgehog 3 & Knuckles
In Sonic & Knuckles, and its lock-on expansion Sonic the Hedgehog 3 & Knuckles, electrical emitters appear in Death Egg Zone as long panels of electricity on the floor and ceiling. Notably, those on the ceilings shoot out bolts of electricity periodically.
Sonic the Hedgehog (Didj)
In Sonic the Hedgehog (Didj), electrical emitters appear in the Scrap Brain Zone portion of Scrap Plant Zone. In this game, they have the exact same appearance and behavior they had in the original Sonic the Hedgehog.
In other media
In the Sonic the Hedgehog comic series and its spin-offs published by Archie Comics, electrical emitters made an appearance in Scrap Brain Zone when Sonic first traversed the Zone. He later encountered them again in Wacky Workbench.