Everything is coming to light, thank you. I will check the datasheet.
I understand everything 10x better when you explain it, though!
The only part I am confused about is that you mentioned....
"Do not assume that you can combine the 10uF with the 0.1uF cap. This is a common error."
But then you said I can use either one (100uF or 10uF) with a .1uF at the out put of the VR?
Srgt Wookie or anyone else that would like to help me.
I finished the sequencer and it seems to have some cliches.
The CD4017 seems not to like the ULN2803. With 7 seven LEDs and leaving the 8th tied to reset(pin15) All 6 work fine in sequence, when it is time to light up the 7th it lights up partially and so does all the other LEDs at the same time...but little fainter.
Also in a dark room I noticed there is a very small output leak to all LED at all times.
And finally the switch is very sensitive, it chases sometimes and jumps out of sequence.
I cut it down to 6 LEDs and tied the 7th to the reset pin 15.
It works now but still "chases" sometimes when you press the switch a certain way.
The small output leak is still there.
I tried to problemshoot and so I build a simple another circuit with another CD4017.
Using only the 4017 and one res (100K) tied from pin 14 to ground.
It works fine without the amplier (2803)
No output leaks, any number of Leds work, but still chases sometimes. So to test the 4017 I suspected I swapped them between circuits.(I built the circuit on IC Sockets)
Nothing wrong with the 4017. Still doesn't work on the primary circuit in question but works on the simple one, the same as the circuits acted before.
I changed the 2803 to a new chip, the circuit does the same.
So any recomendations?
What trans can I use with the 4017. Don't need much current...about 100mA at 5V per channel.
Yes, it wired to the exact pins. The only thing I changed is to use 7 channels so I tied the reset pin to the last unused output.
Attached is the schematic of exactly what I have build.
I tried all kinds of changes afterwords, changed the cap value, removed and replaced the 10K Res, removed the cap that makes the circuit go to back to start of sequence at re-power.
Did all kind of possibilities but the problems still persists.
I am actually trying to fix 3 problems at the same time. Sequence bounce, small leak to all LEDS, and last Led when selected(7th in my case) they all light up.
Since I got the system to work with 6 LEDs I would like to fix one problem at a time.
My biggest concern is the bounce, I have been reading around forums that the 4017 is notorious for having a little bounce, when the push button is activated.
All kinds of solutions have been posted, from adding a small cap across the switch, to changing the value of the res at the clock. Clock from + or clock from -, diode in between, all kinds of circuit changes where the authors swear by it, but it STILL BOUNCES.
Tried about 6 variations of posted solutions, but the clock is so sensitive to that switch.
Pressing the switch ONCE should move the sequence ONCE.....period.
Anything else, besides the bounce, I know can be fixed easily because it is probably a clitch somewhere,(have a cold solder on a pad, etc.)
Is there any way I can control that crazy clock with a push button?
Never mind about the switch bouncing problem, I found the answer.
I will be using a 555 in monostable mulitivibrator, to send only ONE pulse signal to the pin 14 of the 4017 per switch deflection. The 555 is inexpensive enough and only needs one res and one small cap to accomplish this.
Next, in order of importance, why is there a small leak going to all the LEDs off the 2803?
By the brightness you would not even notice it unless you turn the lights in the room off but after I measured the voltage, each LED is getting 1.61V after the current limiting resistor and 1.63V before directly coming from the 2803. A light up LED gets 2.0V
What could cause the amplifier to act like that. I thought we are giving independent
signals one at a time to each individual input or the 2803 to amplify (or turn on) only the corresponding output.
What could be happening...besides the fact that maybe I missed a correct tract connection?
...I checked the circuit 10x!
Well, there must be a small amount of leakage current through the Darlington output transistors.
If you had a relay coil in parallel with your LED like you originally planned, it would probably be so dim that you would no longer be able to see it, even in a dark room.
Yes, I understand. The leak is not enough to activate my relays anyway.
I stand corrected on something. My first circuit had some nasty bounce. The simple one I build without the amplifier.
Your circuit you designed has no bounce. You went off the ground to (high to low) for pin 14 (clk)
Every other design is going off the VDD (low to high) causing the bounce.
( I might have got the low/high reversed in my analogy but I understand the principle now)
The only difference which is no big deal is that on your circuit the sequence changes AFTER you release the switch (because while it is being pressed it is being grounded) and on the other circuit the sequence happens WHEN you press the switch.
I believe I see the logic electronic function.
Is this about right?
By the way, my first circuit with just the 4017 has a silly mistake. The led's resistors get tied to ground not the positive 5V.
....What I meant by your circuit doesn't bounce is that is has very little bounce, once in a blue moon depending how fast you depress the switch.
But is is pretty manageable.
Thanks
I started this thread a few weeks ago determined to build "the perfect circuit" and finally, I finished it.
Here is the final circuit for a sequential push button switch for anyone who wants to built a great circuit where you don't have switch bouncing problems with the 4017.....and with a short beep everytime the sequence advances.
Each advance happens on push and not release of the button.
Here is the corrected Schematic, Also the LEDs were revered.
There is still a consistency problem.
It was working flawlessly on the breadboard...took it apart and put it together twice.
Then took everything apart and started over, the 3rd time the Leds jump erratically (nothing to do with switch bouncing) with the SAME EXACT CONNECTIONS!
I will do it many times until it has 0 errors and the circuit works every time it is assembled. There must be something small I overlooked.
It can't work perfectly one time and not work the second time, assembled with the same exact connections!!!!
It seems that the length of the ground connection that is coming from the power source is very significant.
I had the ground looping all the way at the opposite side of the breadboard to where the circuit was located and then coming back to it(the long way)
When I moved the ground connection closer to the "beggining" of the circuit, feeding FIRST the 555, 4017 and THEN going to the Led's resistors it worked perfectly.