From Dragon Ball Encyclopedia
The Dragon Radar (ドラゴン レーダー, Doragon Rēdā) was a tracking device designed and built by Bulma to help locate the Dragon Balls. This made finding the Dragon Balls more efficient compared to conventional methods. Dragon Balls emitted a faint electromagnetic pulse which the radar could detect. It then pointed arrows in the directions of nearby Dragon Balls. Pressing the button on the top would cause the view to zoom out and show more and more of the planet.
In Dragon Ball, Son Goku accidentally broke the Dragon Radar while fighting aganst Blue. During his search for a capable mind to fix the radar, Son Goku met Arale, from Dr. Slump, who asked her father/creator Senbei Norimaki to fix it. Senbei could not make heads nor tails of it. Turbo, her baby genius "brother", fixed it while nobody else was looking.
The radar is used frequently by Son Goku and his friends in Dragon Ball and Dragon Ball Z, but in Dragon Ball GT the Dragon Radar is assimilated by the robot Giru, giving him the ability to find the Dragon Balls for Son Goku and the others.
 Other radars
Bulma's Dragon Radar is not the only device capable of locating Dragon Balls. Throughout the series, many other devices that work much the same way are also seen. One often seen is the Global Dragon Radar.
 Red Ribbon Army
During their hunt for the Dragon Balls, the Red Ribbon Army had their own version of the Dragon Radar, but it was rather primitive and could only give a general idea of where the Dragon Balls were. Large groups of soldiers had to be dispatched to the location, resulting in many man-hours of backbreaking labor and invading of innocents' homes.
Pilaf eventually built his own, superior version of the Dragon Radar. It was shaped like a globe in order to minimize map distortion. It was installed in his floating airship, and was able to show the Dragon Balls' exact location on the planet.
 Other Z Warrior radars
Along with the Dragon Radars invented by villains, the Z Warriors also had many different Dragon Radars. Although these Dragon Radars did not differ in form or function from one another, they were still different items. In fact, the Dragon Radar used in the majority of Dragon Ball Z is actually not the one Bulma introduced in "The Secret of the Dragon Balls" (that one is presumed to lie dormant in Dr. Slump's laboratory damaged beyond repair).
- Turbo Norimaki created a new Dragon Radar for Son Goku when the old one was stolen by Blue.
- Bulma created a new Dragon Radar at Muten-Rôshi 's prompting during the The Great Demon King Piccolo Saga.
- In Fusion Reborn, Wrath of the Dragon, and the beginning of the Shadow Dragon Saga, the entire Z Warriors team split up into seven groups, each tasked with finding one Dragon Ball. It is presumed that Bulma made Dragon Radars for each of them, otherwise they would not have been able to find the Dragon Balls so quickly.
- There is an iPhone/iPod Touch application that emulates the Dragon Radar. It is named DRadar.
- The Dragon Radar in the live-action Korean film coincidentally resembled the DS series of Nintendo handhelds, as well as the Dual Screen Game and Watch handhelds.
- In Dragon Ball Episode 84, "Rivals and Arrivals", the man running the registration for the Tenkaichi Budokai is looking at a clock that closley resembles the Dragon Radar.
- ↑ As stated by Bulma (Dragon Ball volume 1, chapter 1, pg. 25)