# I was wondering about flip flop circuits

I was wondering about flip flop circuits and how I would have say up to 10 led blink on one moment then the other 10 blink the second moment than back to the first 10 and so on. the flip flips I have seen are single led. is it possible to use the analog and just string the 10 leds together.

p.s. working on an xoxo led sign for valentines. running off 110v would the flip flop option be the way to go or is there another less parts way to go about it. I want the x's to blink on when the 0's are off and the O's on when the x's are off. or the first xo then the 2nd xo. not sure yet. also want the "tempo" i.e. the resistor value to be changeable so i can make it faster/ slower

thank you!

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Jan 23, 2012. 10:57 PMiceng says:
More details,
You can change rate without changing ratio
More C1 to go slower
Less C1 to go faster

Make an Ible about it for us all
Use a 9VDC 150ma Wall Wart

A
Jan 22, 2012. 11:30 PMiceng says:
A uP is the logical choice to do this task.
However I get the impression you want to use individual ICs
What voltage are you going to use ?
What are the LED voltage and currents for each color ?
What timing is your tempo and range ?

A
Jan 23, 2012. 4:00 PMiceng says:
Red LED Volts are 2.0-2.2 ten in series. would be over 20 volts.

Here is a circuit using one 14 pin IC ten Red LEDs for the (X)
and place ten more Red LEDs for the (O)s in place of the green.

A
Jan 23, 2012. 5:38 PMiceng says:
First the red leds are ON with green OFF
then R1, R2, charging C1 time later
the green leds turn ON with the red off.
Then R2, C1 discharge time later Repeat...

Look at the pin numbers 1 through 14 <=> that is ONE IC
I set the resistors to 220 ohms for about 20 ma per LED at 9 VDC
and with 5 groups in parallel that is about 100 ma total
which is well below the maximum 300 ma capability
for each IC output stage.
Jan 23, 2012. 12:16 AMkarnuvap says:
Look at your two transistor circuit for a flip flop. You see the LED in one arm of the circuit and the other half of the symmetrical circuit has a resistor where the LEDs are?

Simply put one set of LEDs in the normal place and the other set of LEDs in place of that resistor. (Keep the circuit symmetrical).  It will work exactly as you describe; one set on while the other is off and vice-versa.

I don't like the sound of you trying to use 110v - this sort of circuit should be run off a 9v battery (or 9v power supply).

A micro processor is Way over the top for this and, with the greatest of respect to Steve, I would go so far as to say that a 555 is probably to much too (though I am a great supporter of this chip).
Jan 23, 2012. 10:41 AMadam 101 says:
I agree with this post. However, if you want to use a wall socket just get a wall wart that will supply 9-12 volt dc (depending on the leds of course).
Jan 23, 2012. 3:52 AMsteveastrouk says:
+1 - good trick, I'd forgotten that !

Steve
Jan 22, 2012. 11:53 PMsteveastrouk says:
a 555, a J-K flip flop and a couple of transistors to drive your LEDs are all you need.

Steve