1. for a photo transistor wich has only 2 leads(a short and a long one) wich one is th emitter and wich one is the collector?
2. a reaplacement for 2n3094 transistor in the Bc series?
I have used BC547/548 instead of 2N3904 in many places and it works for me. Most of my applications were high speed switching. I have't tested it in active region i.e. amplifiers. So better compare the datasheets before replacing it in amplifiers.