I'm trying to power a small loudspeaker (8ohm 0.5W) off an attiny output using a transistor and I have to hand THESE and THESE. I'm trying to calculate my base-pin resistor value but I'm struggling to ascertain what the gain is for either of these transistors: the specs mention "Minimum DC Current Gain" but then display a value in Volts - I thought the gain should be a simple ratio... am I missing something here?
Also, am I right in thinking "Maximum DC Collector Current" is the max current the transistor will allow through the device I'm powering?
Lastly, I remember reading one should be wary of voltage spikes when coil devices discharge and a diode can help protect against this. Should I be worried enough to introduce one here?