The former mayor of Denbigh, John Larsen, had been reporting the explosions, which he caused himself, to the police.
He claimed he found a device planted in an advertising board, and told the shop owners.
Helen Richards, a worker at the shop in Denbigh, said it was "strange", as they had not even noticed, so they told the police to check on Larsen.
In formal submissions before sentencing, prosecuting barrister Wyn Lloyd Jones said people living on, or close to, Lenten Pool Read, where Larsen set off most of his devices, became "increasingly anxious" as the explosions got bigger.
He said: "It had an impact on sleep. There were concerns about property damage or someone being injured."
He said Larsen used his position of public office to "throw people off the scent", organising meetings to discuss the incidents and reporting explosions to the police, and even gave interviews claiming he was concerned for his family's welfare.
Henry Williams is a resident of the Lenten Pool area of Denbigh, who heard the explosions caused by John Larsen, near to their homes earlier this year.
He said he thought it was somebody letting off fireworks, until one Sunday morning when "big damage" had been done to some cars - "and that's when I felt a bit worried."
The jury, of six men and six women, found John Larsen guilty on all five counts, with unanimous verdicts.
Judge Merfyn Hughes QC thanked the jury, telling them they had heard a "very unusual" case.
He told the court he is minded to sentence Larsen this afternoon, indicating that a long custodial sentence is likely.
He said these were "very, very serious offences" and the sentence he will pass will have to reflect that.
The judge at Caernarfon Crown Court has indicated that he is likely to sentence John Larsen this afternoon, and the former mayor of Denbigh faces a lengthy prison sentence, after being found guilty of causing a number of explosions in the town.
Larsen, a Liberal Democrat town councillor, admitted while giving evidence that he experimented with different rocket fuels for fireworks, but denied using gunpowder for explosions.
Residents in the Lenten Pool area of Denbigh, where he lived, were alarmed by a series of small explosions late at night between February and April.
They caused loud bangs, and damage to cars, but nobody was injured.
The former mayor of Denbigh has been found guilty of causing a series of explosions in the town.
John Larsen, 46, had denied causing an explosion likely to endanger life or cause serious injury to property, possessing explosives with intent to endanger life, and three charges of arson.
The jury at Caernarfon Crown Court has found him guilty of all of the charges.
During his trial, the court was told he was responsible for various explosions between February and his arrest in April, of which the most serious involved setting off an improvised explosive device beneath a vehicle, with ball bearings added as shrapnel.
The jury in the trial of former Denbigh mayor John Larsen will continue to consider its verdict tomorrow.
Mr Larsen, 46, denies causing an explosion, possessing explosives, and three arson attacks on cars.
The jury at Caernarfon Crown Court has gone out in the trial of former Mayor of Denbigh John Larsen.
He denies charges of causing an explosion, possessing explosives and three arson attacks on cars.
North Wales Police have launched an inquiry following the discovery of a man's body in Denbigh today.
The body, which was found near a multi-storey car park on Factory Place, is believed to be that of an 18-year-old from the area.
The death is being treated as unexplained, with a post-mortem due to be carried out on Saturday.
The future of a derelict North Wales hospital which it is hoped could be key to the economic regeneration of Denbigh has taken another twist today.
Denbighshire County Council has decided to press ahead with a compulsory purchase order - it says that is in order to protect the building from further ruin. But today the current owners of the site told ITV News that they would be opposing the move - which will need a public inquiry.