I'm attempting to control a salvaged VFD display from a CD player. I power the filament from the arduino (3.3V). I power the grids and segments from an external 12V power supply.
I can power up a grid and a segment with 12V and it works. That is, I have to two 12V connections active (grid + segment). Now, I would like to turn the connection powering the segment on & off from the arduino using a transistor. Looking at the specs of the BC547B NPN transistor (See below), my understanding is, that it should work.
I insert the transistor in the connection to the segment (12V to the collector, emitter to the display). I thought I could now turn on the segment by connection 3.3V or 5V from the arduino to the base of the transistor, and the segment would light up. This is not the case however. What could be wrong? I have been experimenting with LEDs and transistors with the 5V from the arduino with success.
Any guidance, hints or suggestions much appreciated.
Some info on the VFD: Filament draws 111mA (3.3V). A grid draws 3mA (12V) A segment draws 0.2mA (12V)
Transistor info (BC547B): Vcb max(V): 50 Vce max(V): 45 Veb max(V): 5 Ic max(A): 0.2 hFE (min): 200