Thermometers?

Rayna • TTC #1 for a 2015 baby. Miscarriage in May 2013.
Does it matter what kind of thermometer you use to get your bbt? I39m just curious. I39ve been told it doesn39t matter and then I39ve been told it does. I39m just curious if I use a normal thermometer for a few days until I can get a bbt thermometer if it39ll matter or should I wait until I get one.