Throughout The Troubles, the Provisional IRA made extensive use of IEDs in their 1969–97 campaign. They used barrack buster mortars and remote controlled IEDs. Members of the IRA developed and counter-developed devices and tactics. IRA bombs became highly sophisticated, featuring anti-handling devices such as a mercury tilt switch or microswitches. These devices would detonate the bomb if it was moved in any way. Typically, the safety-arming device used was a clockwork Memopark timer, which armed the bomb up to 60 minutes after it was placed by completing an electrical circuit supplying power to the anti-handling device. Depending on the particular design (e.g., boobytrapped briefcase or car bomb) an independent electrical circuit supplied power to a conventional timer set for the intended time delay, e.g. 40 minutes. However, some electronic delays developed by IRA technicians could be set to accurately detonate a bomb weeks after it was hidden, which is what happened in the Brighton hotel bomb attack of 1984. Initially, bombs were detonated either by timer or by simple command wire. Later, bombs could be detonated by radio control. Initially, simple servos from radio-controlled aircraft were used to close the electrical circuit and supply power to the detonator. After the British developed jammers, IRA technicians introduced devices that required a sequence of pulsed radio codes to arm and detonate them. These were harder to jam.