I've been wrestling with a circuit I'm trying to build for a few days now and a friend recommended I ask for advice here. I'm essentially trying to create an electronic switch controlled by a raspberry pi. The switch will open and close a circuit for a heating coil that needs about 0.25A and 5V and is running off a battery pack. The issue I'm having is coming up with a set of transistors or some other configuration that can allow the Pi to toggle power to the coil using only it's 3.3V output. I've fried several transistors already and have moved to Mosfets which are causing their own problems. If anyone has a recommendation or a simpler way of doing this I'd be very grateful. It's the final component I have to contribute to a group project I'm working on. Thanks!