Isochronus Cyclotron

"It measures the resonant frequencies of the monolith piece..." "... and locks onto the frequencies in the monolith through space-time."

- Jemma Simmons and Leo Fitz

The Isochronus Cyclotron was a device built by Owen Shaw using Leo Fitz's schematics which could use the White Monolith to transport people through time.

History
"That damn thing drew a year's battery reserves when he fired it up. Didn't think it did anything, but sure enough, here you are. Heroes from the past."

- Samuel Voss to Leo Fitz and Jemma Simmons

In a timeline where the Earth was destroyed, S.H.I.E.L.D. agent Leo Fitz worked on several leads to reverse this cataclysm. Among those leads were the use of the White Monolith, as its frequencies could be targeted across space-time to transport people through time through an Isochronus Cyclotron Fitz designed. However, Fitz never built the device himself, and only left the designs of the equipment.

The designs were later recovered by Owen Shaw, Fitz' son-in-law in this timeline. Shaw was able to build the Isochronus Cyclotron, which was kept in the remnants of the Zephyr One where the True Believers survived on Earth. In 2091, using a fragment of the White Monolith he had taken with him when exiled from the Lighthouse, Shaw activated the Isochronus Cyclotron, which resulted in the arrival of a team of S.H.I.E.L.D. agents from another timeline after they were kidnapped by Enoch, so they would be made aware of the future destruction of Earth.

The Isochronus Cyclotron was found by S.H.I.E.L.D. after they found shelter in the Zephyr One following their escape from the Lighthouse. Fitz and Jemma Simmons eventually figured out that the device worked in conjuction with a fragment of the White Monolith which had been found earlier by Phil Coulson, although they also knew that they would need the entire monolith as well to return into their time.

To that end, S.H.I.E.L.D. returned to the Lighthouse with the Zephyr One, only leaving Enoch behind to watch and prepare the machine while the rest of the team would find the Inhuman Flint, whose powers could be used to build the Monolith. However, while preparing the machine, Enoch was found by a Kree guard, and the machine was damaged in the subsequent fight which ended when Deke Shaw saved Enoch.

Enoch and Shaw attempted to repair the equipment supposed to power the Isochronus Cyclotron, but as their efforts failed, Enoch suggested using his own batteries instead. Although this meant death for both of them, Shaw agreed to this plan and connected Enoch to the cyclotron. Shaw then waited until the last moment for the whole team to be gathered in the Lighthouse in front of the monolith before activating the Isochronus Cyclotron. The machine then unleashed the potential of the monolith, sending S.H.I.E.L.D. back into their time. While Enoch was indeed destroyed, Shaw, however, was hit by a fragment of the White Monolith from the machine, and was sent in the other timeline as well.

Appearances
In chronological order:
 * Agents of S.H.I.E.L.D.
 * Season Five
 * All the Comforts of Home (mentioned)
 * Season Six
 * The Other Thing (mentioned)

In an alternate timeline:
 * Agents of S.H.I.E.L.D.
 * Season Five
 * The Last Day
 * Past Life