- Joined Feb 4, 2018
I'm running a small servo off an ATTINY85. The servo pulls around 250mA and the MC maxes out at 40mA per pin. While testing I'm powering the Servo and MC off my adjustable power supply and only the pin for controlling the servo is connected to the MC and everything works fine. I currently only have a BC337 transistor and either I'm not wiring it up correctly (I'm still a bit of an amateur at this stuff) or the BC337 isn't correct for this application. My best guess is it doesn't switch fast enough for the quick pulses that are sent to control it. I'm not sure where the datasheet would tell me that. But the duty cycle of the servo is 1-2ms, so it would need to be able to switch that fast. Also I have the Collector/Base/Emitter wire up to PWM servo pin/ MC's output pin/GND(for servo,pwm) respectively. There's a 1k resistor in series with the collector and a 4.7 resistor in series with the base. So I need to know if it's wire up wrong or I the wrong transistor.