Blaster turrets can be found on the outskirts of AI bases (never inside them) and within player settlements. They can only sense their targets if they are within range and view of the blue eye on top of the turret. The eye will turn red when it senses enemies. It requires a source of power in order to function, and removing its power source will disable it.
Blaster use the same ammunition as the Blaster Token. A weapon that can be possessed by players. The blaster turret can be recognized at distance by the bullets that it projects in your direction, they are rapid fire small colored dots.
Players can take advantage of unpowered blaster turrets (and all other kinds of turrets too) and use them as convenient out-of-base defenses simply by re-powering them.
Blaster turrets are the low-level turrets in in Love, others include: Rocket turrets.
More information can be found at Power Usage regarding power issues.