In Pete's World, the Preachers possessed electromagnetic bombs created by Angela Price that were used to destroy computers. Using one on a Cyberman had the effect of crippling it and disabling its emotional inhibitor. (TV: The Age of Steel) An EMP device was used when the Preachers attacked the Cybus factory in Paris. (GAME: Save Paris)
Since Bannakaffalatta was a cyborg, his body contained a device capable of emitting an EMP which would temporarily shut down Heavenly Hosts. In generating the electromagnetic pulse, Bannakaffalatta drained almost all his power, dying shortly thereafter. However, Mr Copper, Astrid Peth and Rickston Slade were able to obtain the EMP device, recharged it, and used it as a weapon against other Hosts.
Mr Copper also used to sell EMP transmitters on Sto to the discriminated cyborgs, reminiscing, "They'd always give me a bed for the night in the cyborg caravans. They're good people." (TV: Voyage of the Damned)