The governments of Thailand and Britain have deemed the GT200 bomb detector unreliable, but the Thai military continues to use it to make arrests in the Muslim south.
Nearly 1,000 refugees were detained on a remote island in December before being towed out to sea and abandoned with little food or water, rights group says.
Largely untested, opposition leader Abhisit Vejjajiva says his first priorities are fixing the economy and rescuing the tourist industry.
The interior minister says it could calm the insurgency-racked south. Opponents see a step toward secession.
The majority coalition is expected to name a controversial prime minister.
In 2003, a violent government antidrug campaign resulted in more than 2,500 deaths.