Hi Henk,

to drive the segments of 10 digits multiplexed with the 4050 (deliver only 3.2mA) you overload the 4050 many times. You need minimal AC drivers (deliver 48mA) e.g. 74ACT595 to get a bright display.

Also brightness depends only from the current, so 15V give only more power dissipation.
Yes, at 15V the 4050 can drive 24mA, but this cause, you use 13V for heating (on about 2V for the LED).

Maybe, the many circuits, resistors and transistors of your solution are cheaper, but using 5 TSM7752 displays are many times easier to make the pcb and the software.
E.g. on using 5 TSM7752 you need only 3 output pins of your micro to connect they all. So a single side pcb can easy be made.
Then the whole cost (including developing time, pcb cost) can be opposite.


I used also solutions, similiar to yours, 15 years ago, but now I think, enough driver circuits available to to the job better.


On applications with analog components it can also be important, that multiplexed displays generate more EMI (electrical noise). And the TSM7752 is not multiplexed (all segments separate DC driven).


Peter