/diy/ - Do It Yourself

>>1148820
how do you switch the high side personally?.

make a clock with this smaller dirt cheap 8x7 seg tube a while ago.
ended up with 2x 74595 driving 2x uln2803.
the high side pulled up with resistor arrays, then shorted to ground b the ulns.

bright and efficient non the less. though it was funny how it pulled more current NOT lighting a digit.

>>1008418
>recommending discrete darlingtons transistors, not glorious darlington arrays like uln2003/2803
with these arrays you need no passives and they are cheap as chips.
i do agree with using shift registers though.

the 74595 and uld2803 has been useful to me so may times.
for example i use two of each to much this VFD.

VFD's are quite simple, but also a bit different from other displays.

here i got the filament running on 5v by adding a 100Ω in series, look at the datasheet and applying ohms law.
for a segment to light, the segment AND the digit must be high, because they are really anodes and grids in a vacuum tube.

since the current is so low, you can pull all both grids and anodes high with 100kΩ resistors and pull them down with uln2803's
here i run those uln2803's from 2x 74595 shift registers.

this needs to be multiplexed of course.