Circuit Design Question?

Question

I need to design a circuit that will count to 3 using a pushbutton and 3 LED's. (1 push, 1 led lights... 2nd push, 2nd led lights, 3rd.... and the 4th push clears it.) I am using a 74175 IC for the counter. Any ideas on how to hook this thing up? Thanks.

Answer 1

what you need is a shift register. Try this:

connections (assuming the 16 pin package):
pin 2 to pin 5
pin 7 to pin 12
pin 11 to pin 13
pin 14 to pin 4

LED 1 (anode) to pin 2 (other side of LED to GND)
LED 2 (anode) to pin 7 (other side of LED to GND)
LED 3 (anode) to pin 10 (other side of LED to GND)

push button to pin 9 (other side of switch to GND)
a resistor (say 10k) from VCC to pin 9
VCC to pin 1 (and 16 VCC pin)
GND to pin 8 (GND pin)

This basically takes the Q output from FF1 to the input of FF2.
The Q output of FF2 to the input of FF3.
The Q not output of FF3 to the input of FF4.
The Q not output of FF4 to the input of FF1.
The LED's are off of the Q outputs of FF1, FF2, and FF3.
The switch is on the CLK input with a pull up resistor.
The CLEAR pin is kept high.

I havent actually tried this, but just by looking at it real quick I think it will work.

Answer 2

correctly?