Need Help with simple sequential LED circuit

[testerthe]

this will be my first circuit project and i am at lost.. i am currently learning about flip flops and how to design.. i am trying to make a sequential circuit that with one pushbutton with 4 led outputs, first press will turn on 4 leds, second press will turn on 2 leds and third press will turn off all leds and restarts.. is there any design i can look at as a reference?

tnx in advance..

 

[carbonzit]

I think there are some circuits here on this site that are very close to what you want. What you describe can easily be done by a single counter chip. You basically have 3 states: 4 LEDs on, 2 LEDs on, all LEDs off. You can use a 3-stage counter to cycle through these states.

So you'd need at least 2 chips, the counter, plus another chip to debounce the pushbutton switch. (Look up "debouncing" on this site and you'll see lots of posts on the subject.)

It's a pretty simple circuit, but unfortunately I don't have a schematic to give you. I'm sure someone else here can, though.

 

[Dragon Tamer]

Sounds like a binary counter.



Try using that circuit, just remove the 555 and replace with a push button and a resistor series for you circuit.

 

[carbonzit]

Or how about two S/R flip-flops? And you left out the switch debouncer. (Which I found out is necessary the hard way.)

 

[crutschow]

Below is a simulation of a circuit using two D-type flop-flops to give the sequence you want. You connect two LEDs to the output of the first FF and two LEDs to the output of the second.

As you can see the first button push changes both FFs, turning on all LEDs. The second button push turns off the first FF, leaving two LEDs lit. The third button push turns off the second FF, to go back to the start of the sequence.

You can use a CMOS FF such as the CD4013. Depending upon the current requirements of the LED you will likely have to add a transistor buffer driver to the outputs of the FF. It wasn't required in the simulation since it uses an idealized FF model that can deliver infinite current.

I didn't show the unused inputs tied to ground, but they must be in the actual circuit to avoid erratic operation. Also the IC power and ground connections are not shown, which must be added.