ljcox said:
The resistor between the base and gnd is not necessary in this case since the switch shorts the base to gnd when closed.
Len
The circuit also doesn't make any sense?, it's dropping the entire supply voltage (minus the Vce of the transistor and 0.7V drop across the emitter diode) across the relay. So effectively all it's doing is putting a diode in series with the relay coil and dropping 0.7V?.
I 'suppose' by carefully selecting the base feed resistor you could only turn the transistor partly ON, but this would dissipate the excessive heat inside the transistor, most probably causing it to fail?.