/diy/ - Do It Yourself

>>1283478
I see, the 2R7s are surplus to requirements.
>brightness fail
That happens if you try to save on resistors or current sources by putting only one on each digit line instead of one on each segment line, or if the power supply just can't hang.

>>1283632
No. Look at the bottom. All your emitters are connected together.
You really need something more like a switch for this. If you're tight on input pins, you really need an analog mux, which combines the decoding and the switching in one package. Consider the CD4052 analog DP4T multiplexer, Pic related. It can handle a very modest amount of current without introducing a whole lot of error, about 150 ohms or so, fine for a 10k pulldown. You could connect up to 8 sensors to this, if you use the other half of the mux. You could also move two of the sensors to the other half of the mux if you wanted to compare them at an instant.

>>1283624
Depends on what the reverse Vce on those is. I'd rather just leave them float.