A technical malfunction in a bomb, detected a day after the July 25 blasts in Bangalore, saved the city from a ninth blast. Investigators also noted that unlike the bombs used in other recent blasts in the country, this one was equipped with a microchip as its timer.Found on a footpath outside the Big Bazaar in south Bangalore, the bomb’s electronic printed circuit board (PCB)—used as the timer—did not work correctly, surmised investigators after testing its circuitry. In order to ascertain the time the ninth bomb was set to go off, bomb experts connected the PCB or microchip to the display of a clock to find the alarm settings for the clock microchip, but their efforts yielded no results. “We tried to see what time the buzzer would go off if the PCB was connected to the display of a clock. The buzzer did not go off at all. This may have prevented the bomb from going off,” a senior police official said.The Karnataka police roped in experts from the National Security Guard (NSG), forensic specialists and technicians from Bharat Electronics to ascertain the timing on the PCB as well as other aspects of the device. Experts said the PCB, connected to a 9-volt cell for power, could have been derived from a radios with clock functions, a mobile phone or even a toy or videogame The battery power could keep the clock running for days, sources said.While only one microchip has been recovered from the unexploded bomb, police have arrived at a tentative conclusion that all the devices that exploded in Bangalore also used similar PCBs. Members of the NSG’s National Bomb Data Centre have told the Karnataka Police that the use of a microchip to trigger bombs has been observed for the first time in the country. In the recent bomb attacks in Hyderabad and Jaipur, cellphones or quartz clocks have typically acted as timers. Notably, the bombs that caused the Ahmedabad explosions also used commonly available quartz clocks as timers.Police efforts to find a timer in a trunk—found dumped on the Bangalore-Mysore highway a day before the blasts—containing a large quantity of yellow ammonium nitrate, 32 live detonators and nuts and bolts have proved futile. The detonators and explosives found in Channapatna are believed to have been part of the process of creating the bombs that jolted Bangalore. The yellow coloring for the normally white ammonium nitrate is believed to have come from a chemical additive that investigators are trying to separate through scientific analysis.Investigators have also noted that apart from the modus operandi of planting a series of bombs in public places, the only other real technical commonality between the Bangalore and Ahmedabad blasts is the ammonium nitrate — the primary explosive material. While the bombs in Ahmedabad were packed in wooden boxes with ball bearings serving as projectiles, the bombs in Bangalore looked like cement buckets with nuts and bolts embedded in the cement casting serving as projectiles, experts said.In the meanwhile, experts in Karnataka are speculating that the large quantity of yellow ammonium nitrate was derived privately, as against the industrially available material. Also, the set of four pipes welded together — in itself a probable explosive device — from the Channapatna site suggest that the bomb makers were technically proficient enough to experiment with manufacturing different types of explosives. Senior police officials in Karnataka continue to maintain that the Bangalore operation was carried out locally, with the probable exception of the bomb maker and masterminds. Police are trying to narrow down their search by identifying skilled bomb makers, including those who are in jail at present.
