Turnbull was denied bail after pleading not guilty while facing Penrith Local Court via video link.

He was arrested on Wednesday at Beaumont Hills and charged with possession, supply or making a prohibited device and possession of a prohibited device. His mother had called police when she found a suspicious object  in his Werrington County bedroom on Tuesday night.

By applying for bail, it meant Turnbull's previous criminal history and the fact he was on parole was revealed and considered by Judge Dorelle Pinch.

After giving her reasons as to why bail was refused, Judge Pinch then asked Mr Turnbull if he had anything further to say. Unaware it bail had been refused, he asked about it again.

When Judge Pinch clarified that she had refused bail, Turnbull gave an expletive-laden response, and knocked over his chair.

In making her decision, Judge Pinch had read information from the police statement of facts indicating the improvised explosive device contained ball bearings, pieces of shrapnel and fishing sinkers that were found by police when it was detonated in a field after it was removed from the man's home.

Police allege the device was obtained by Mr Turnbull when he walked out of his house to a silver vehicle on Tuesday night and took possession of a rectangular shaped bag, that he brought into the house before he left in the same car.

Judge Pinch said the prosecution, led by police prosecutor Ben Seabury, conceded Mr Turnbull may not have known exactly what was in the bag  but he did know of a detonator.

She said Mr Turnbull was shown the device and made comments about it. Knowledge of the device would play a large part in the defence's case.

Judge Pinch said Mr Turnbull said the device, "looked cool", and was something "you could switch on and off" and "like a bunger".

The matter will be heard again at Penrith Local Court on February 26.