I am going home for vacations to the Philippines and I took a Turkish Airline Flight with a layover of 18 hrs and it includes a change of airports. Do I need a transit visa?
As stated in Timatic, the database used by airlines:
Visa required, except for Nationals of Philippines with a normal passport can obtain an e-visa before departure at www.evisa.gov.tr if they have a valid on arrival visa or a residence permit issued by Ireland (Rep.), USA, United Kingdom or a Schengen Member State
So if you have a valid visa or residence permit from Schengen, the UK, Ireland or the US, you can get an eletronic entry permit here.
Otherwise you need a visa.