Re: 7 seg display driver
I understand that you are not familiar to the IC, especially logic and microcontrollers.
Using 49 diodes is one of the solution, however, it is so "rough" and when there is a problem, it is hard for you to point out it as it is so complicated.
You need not to use the microcontrollers as you do not want to write codes.
But I believe that if you look through the datasheets of the logic 74LS147 and 74LS47, you can easily understand how to make your circuit in very simple way:
74LS147 is a 10-line to 4-line (decimal to BCD) priority encoder. If all of 9 input set at logic 1, so all output are set at logic 1 which corresponding to number 0.
If any input is set at logic 0, regardless the other inputs at any logic level, so the ouputs are set at the corresponding number.
4-line outputs (BCD) are interpreted in to number (LED 7-segment display) by the 74LS47, it is the BCD to 7-segment decoder/driver.
All inputs of 74LS147 are pulled up to +5V through resistors of any in range of 1kohm to 10kohms, and your 9 switches (normally opened) connect the inputs to ground.
That is all of the idea. As I do not know how to draw the circuit and post on to forum, so I hope all my explanations are clear enough for you.
Goodluck
nguyennam