AN Australian investment banker who admitted chaining a fake bomb to a teenager in a blackmail plot has been jailed for 13-and-a-half years.

Madeleine Pulver, then 18, was studying at home alone in her family's Sydney mansion last August when Paul Peters walked in wearing a ski mask.

He tethered a bomb-like device to her neck along with a ransom note, then slipped away.

It took a bomb squad 10 hours to remove the device, which contained no explosives. Judge Peter Zahra said: "The terror instilled can only be described as unimaginable."

Ms Pulver hugged relatives after the sentence was read and her father, Bill Pulver, wiped away tears.

The judge gave Peters less than the maximum sentence of 20 years due to his plea and as he was probably depressed at the time.

Peters, 52, fled to the US, but was later arrested. He pled guilty in March to aggravated break and enter and committing a serious indictable offence.

The defence said he was depressed, drinking and exhibiting wild mood swings beforehand. He was obsessed with a book he was writing about a villain out for revenge, his lawyer said.

Peters said he had no memory of the crime. But prosecutors said his actions were down to money.

Ms Pulver said: "I'm pleased at today's outcome and I can now look to a future without Paul Peters's name being linked to mine."