Nigel Goodwin said:
You have the two bases joined together, so both transistors are permanently ON.
Hi Nigel, thanks for your reply.
Why would this happen when the one transistor is NPN (BC547) and the other is PNP (BC557)?
As far as I know, the base of BC557 should be below 4.3V to turn the transistor ON, and the base of BC547 should be above 0.7V to turn that transistor ON.
So when the bases are 0V, only the BC557 will be ON, and when the bases are 5V only the BC547 will be ON.
What do I misunderstand about transistors?
Regards,
Futterama