Purpose of this A-STABLE circuit

[dan1098]

We have been given this circuit to determine the purpose of it, but I have no idea what it does. I heard someone say they are for spotlights in a nightclub for example.
I have worked out some graphs in which is oscillates, and found the period of the P- but was stuck from here.

I have attached the circuit on this post for a clearer view. From my guess is that is used for a clock but might be wrong and thinking of something completely different?? Because it has an A-Stable and a COUNTER, it resets from point R.

Could someone please tell me how 1) this circuit could be used for spotlights or a clock? and 2) how to actually determine what it is used for?

Thank You
Dan

 

[jpanhalt]

Start at the left and work to the right.

You are correct that the Schmitt inverter is configured as an oscillator. See Figure 6 here: https://www.electro-tech-online.com/custompdfs/2012/12/AN-118.pdf

Ask yourself what happens when Input E is grounded.

What if there are two inputs (i.e.,. two grounding events)?

What does the counter then do?

As for operating lights in a Disco, that is a just a guess. (I do not agree with it.) If your instructor is any good he wants you to figure out what the circuit does logically, not make wild guesses. In fact, such wild guesses would get a very low grade from me.

If you are then asked how you would apply the circuit, then let your mind be creative. For example, I think the circuit could be used to measure psychological stress in mice.

John

 

[dan1098]

Thank you jpanhlt, on my starting post, me saying that it was operating lights in a disco was not a wild guess, i just over heard it and wandering for one, if this was true, and if was true how it worked.

Could it be used for a stopwatch or a clock? Because a counter with a reset is involved, and this is shown on the graph I have done.

 

[jpanhalt]

Please share your graph and explain how you concluded it could be a stopwatch. The reference I gave describes how the oscillator functions. The datasheet for a four-bit counter will explain how it functions. I would then describe what happens to the "counts" in the counter the functions of the AND and NAND gates to get Q.

I really don't think the instructor is looking for a single-word answer like, "stopwatch." Although, that may be one valid use of many. I believe if a student replied to this problem like that, he should get a pretty low mark with a comment something like, "Show your work." But then, maybe education has changed.

John

 

[dan1098]

i was only suggesting it could be a stopwatch- I was not doing an essay. I am not great at electronics but I do like to learn more. Here is my graph.
I need something easy or easy to write about about the use of the circuit. Following the stopwatch suggestion could be that because (not even my explanation could be correct) the counter has four inputs (A,B,C and D), the A counts for 1, B = 2, C = 4 and D = 8 (not sure what these are called, logics?). And in relation to truth tables, the counter will display up to the number 15. So it could count up to 15 and because the user can reset it, it will go back to zero. Would this be acceptable do you think? Obviously I will include a lot more detail in my write up, but am I along the right lines about this?

DanView attachment 69017

 

[jpanhalt]

I need something easy or easy to write about about the use of the circuit. Following the stopwatch suggestion could be that because (not even my explanation could be correct) the counter has four inputs (A,B,C and D), the A counts for 1, B = 2, C = 4 and D = 8 (not sure what these are called, logics?). And in relation to truth tables, the counter will display up to the number 15. So it could count up to 15 and because the user can reset it, it will go back to zero. Would this be acceptable do you think? Obviously I will include a lot more detail in my write up, but am I along the right lines about this?

A,B,C,D are not inputs. How would you explain their connection to the two logic gates, if they were inputs?

Look at this counter diagram or any other one you have:
View attachment 69020

Now, ask yourself (e.g., make a table) what the output of the AND gate will be for counts 1 to n (be sure n is >6). Do the same for the NAND gate. What does the AND gate do when it goes positive? What will the NAND gate be at that point?

John

 

[Roff]

There are no NAND gates in the original circuit.

 

[jpanhalt]

You are right. Yesterday was a bit of an off day for me -- too many other things going on. I must have been cross-eyed and saw the circle for the output as an inversion. Obviously, Q should have been been negated too, if that were the case. Sorry about that.

John

 

[dan1098]

i am slightly confused now

 

[Roff]

i am slightly confused now

It helps if you are more specific. Confused about what?