I have 2 separate 7555/4017 LED free-running circuits, each with 10 LEDS (pretty much standard from a million schematics on the internet), running off of 9vdc.
I would like that when the D6-LED (Pin 14 on the 4017) on both of the separate boards illuminate, a Piezo Buzzer sounds for 3 seconds (approx.), and 2 leds light.
No matter how long both leds on the 2 separate boards are lit, the Piezo only sounds for 3 seconds (approx.), and the 2 LEDS illuminate.
Its kinda hard to explain, but any help is greatly appreciated...THANKS!!

 

The piezo buzzer is simple but I don't understand how long you want the LEDs ON for.

 

OK, first question is about the piezo device: Is it a complete package that buzzes as long as DC is supplied?What voltage and current are required? Or is it just a sounder that needs an external driver?
Triggering based on both LEDs being driven will require an "AND" function, operating the sounder will require either a switch and a timer or else an "AND" function including a timer.. Finally, how accurate a time interval? 3 seconds or 3.00 seconds? Also, what sort of voltages and frequencies are present in the associated circuits?

 

- Or is it just a sounder that needs an external driver?
No the Piezo has an internal driver at 3-9vdc
- Finally, how accurate a time interval? 3 seconds or 3.00 seconds?
Approximately 3:00 seconds, accuracy is not needed
- Also, what sort of voltages and frequencies are present in the associated circuits?
Its running from 9vdv battery

 

Do you mean whenever D6-LED is on then sound buzzer for 3 seconds but other LEDs only stay ON for as long as D6-LED is ON?

 

Schematics are the language of electronics.
If you show us how you wired it to obtain the anomalous behavior, then we can start to provide accurate suggestions.

 

The red LED is Pin:1. This circuit x2

 

You said D-6 LED pin 14 which isn't correct now you mean use pin 1,the Q5 output?

 

pin 1,the Q5 output, is correct, previous was my mistake

 

pin 1,the Q5 output, is correct, previous was my mistake

OK, can you answer my question in post #5?

 

OK, can you answer my question in post #5?

I posted the schematic in post:6

 

That doesn't answer my question.
But here is an observation: As fast as that chaser is moving the Q5 output will be ON and OFF so much that the buzzer will be on continuously.

 

That doesn't answer my question.
But here is an observation: As fast as that chaser is moving the Q5 output will be ON and OFF so much that the buzzer will be on continuously.
The chaser is running fairly slowly. so the 2 outputs from the 2 separate circuits dont match very frequently, but when they do, I want an alarm for 3 seconds only. If the 2 outputs match for a long period of time, they can trigger the alarm repeatedly for a 3 second period, until they no longer match

 

View attachment 327332
The red LED is Pin:1. This circuit x2

Ignore any schematics drawn like that.

1. The colors are useless and distracting.
2. With 3 resistors being used, component designators are mandatory.
3. The battery is wired backwards.
4. The 555 timer symbol isn't as bad as many, but still bad. They misspelled the abbreviation for threshold. More judicious placement of the threshold and discharge pins would have eliminated a wire crossing. Inputs primarily on the left and outputs primarily on the right to facilitate the preferred left-to-right flow.
5. The connection dots with humps style went out 50 years ago.
6. The placement of the power connections for the CD4017 is asinine - they had to do a wire crossing for the poor placement.
7. If they're going to show power connections for CD4017, they should show the decoupling cap(s) too.
8. I think many would prefer a vertical component orientation for resistors and LEDs (i.e. not sideways).

(pretty much standard from a million schematics on the internet), running off of 9vdc.

Yeah, but which one are you using?

 

 

View attachment 327347

Ignore that one too.

1. Pin numbers should be on the outside of the symbols.
2. Pin function should be labeled.
3. No current limiting resistor for the LEDs.
4. CW direction for pot isn't indicated. Mirroring would have eliminated a wire crossing.
5. No component designators.
6. Connection dot missing for ground symbol (because wiper connection doesn't use a hump).
7. Control pin is missing from timer symbol. I'd swap threshold and trigger positions based on how the timer is typically used.
8. And the useless color...

 

You need to put current limiting resistors on your LEDs. Since only one LED is on at a time, you can use a single resistor between the common cathode connection and Vss.

The CD4017, at a 10 V supply voltage, is only spec'ed to be able to typically deliver 2.6 mA and may only deliver 1.3 mA.

 

For the description in post #1, the circuit you want is called a monostable, with an AND gate added to its input. When both counter 1 AND counter 2 are in the desired state, the monostable is triggered. During its timing period, the input is locked out and the circuit ignores all signal activity. The output of the monostable cannot source/sink enough current to drive your devices, so it drives a transistor, which drives the LEDs and beeper.

All of this can be done with one CD4093 quad Schmitt trigger NAND gate, one 2N7000 n-channel MOSFET, and some R's and C's. Schematic later.

ak

 

Can

All of this can be done with one CD4093 quad Schmitt trigger NAND gate plus one 2N7000 n-channel MOSFET. Schematic later.

Can you show us schematic?

 

I would like that when the D6-LED (Pin 14 on the 4017) on both of the separate boards illuminate, a Piezo Buzzer sounds for 3 seconds (approx.), and 2 leds light.
No matter how long both leds on the 2 separate boards are lit, the Piezo only sounds for 3 seconds (approx.), and the 2 LEDS illuminate.

Only included 1 LED because description is vague.

Its kinda hard to explain

Even harder for us to implement...