Objective Development Forums

Hi,

at the cathode of the diode I only get ~4.8V. After the resistor from the AVR-pin and before the Base of Transistor the Voltage differs only from 4.5 to 5 V. So that the transistor is not switching. What's my fault?

Thanks

This is an NPN transistor. The voltage at the base should never exceed ~ 0.7 V. If you measure 4.5 to 5 V, the transistor is not connected correctly or it's broken.