Simple LED Push Button Sequence

[Galaxy]

Hello everyone, I'm working on a small hobby since its been a while since High School and remember going on here long time ago for help and ideas I thought I come back for another project .

I would like to have 9 LED's on my circuit board and have one of those LED's constantly on until I push a button for the next LED to light up in sequence. When it gets to the 9th LED it will go back to the first one when the Push Button is pressed again. I'm not sure if I'm explaining this correctly so I will attach a picture to make it a bit more clear for you. How would I be able to accomplish this project?

Thanks

 

[Mike_2545]

Use a 555 one shot, to feed a pulse to a counter chip (take your pick) something like a 7490, and then feed that to a BCD to decimal decoder like the 7442.

Or use a microcontroller

 

[Ayaskanta]

Ring Counter (7495) would be my pick and use the monoshot as your push button

 

[Mike_2545]

The 7495 is a 4 bit right shift/left shift register.

 

[Roff]

A CD4017 is the simplest counter to use.

 

[Ayaskanta]

yes the 7495 is indeed a shift register... either the LSB output or the MSB output can be fedback to the serial input line to convert it to a ring counter

 

[Ayaskanta]

oops sorry my mistake... the number 9 skipped my mind... sorry!

 

[colin55]

Just use a 4017 with a switch on the clock line and an electrolytic to debounce the switch. You can get it to count to 9 with an "off count" or 10.

 

[Roff]

The circuit below should work. You'll need a 4017 with Schmitt trigger clock input. TI and NXP (Philips) both make these.
If you have to wait too long before being able to advance the sequence, try making C1 or R2 a lower value.

 

[colin55]

You don't need transistor buffers for a supply above 9v. The chip will deliver over 10mA per output.

 

[Roff]

You don't need transistor buffers for a supply above 9v. The chip will deliver over 10mA per output.

Although I selected the value of R3 to allow about 10mA (more or less depending on LED fwd voltage), my intent was to allow higher currents by changing the value.

 

[colin55]

How much more current do you want to deliver?

Use 12v, if you want to deliver 20mA from the chip.

 

[Roff]

How much more current do you want to deliver?

Use 12v, if you want to deliver 20mA from the chip.

Are you saying there is no situation where the transistors are required?

 

[colin55]

No. I am not saying that.

 

[jmb4370]

In the "push to advance" LED circuit like in Ron's post #9, each LED stays ON until the next one is lit with another push of the momentary swtich, as the OP asked for. Besides connecting a 555 as a monostable to each emitter of the outputs, is there another simpler way to make the different LEDs lite up for just a brief moment, say 0.1 second?

 

[Mike_2545]

You could use a microcontroller

 

[jmb4370]

Well, the microcontroller route is the next part of my electronics learning curve, and it seems that most things can now be done simpler with a microcontroller...but the question was really given the circuit as attached by Ron in post # 9, is there another way to make the LEDs light for just a brief pulse as opposed to staying on until the next press of the input switch. This is not a school project, but indeed a hobby for fun and learning.

 

[colin55]

You could put an electrolytic in place of the LED dropper resistor and a diode on each output to discharge the electro.

 

[jmb4370]

I think you are saying to put an electrolytic capacitor instead of the currently shown 620 ohm resistor, but I am not exactly sure where the diode is connected into each output, and then how it can discharge the capacitor. Will a separate capacitor be needed for each output instead of the currectly shown common dropper resistor?

 

[colin55]

Put a signal diode across each LED, with the cathode connected to the output of the chip.
This will discharge the electro when the output goes LOW.