Hi!!,

I have a question regarding designing 3 sequential circuits using an op-amp, diode, and transistor. Question is described below.

The circuit is a comparator that supplies a 3-step sequence of output signals.
The circuit should behave in the following manner.
* Pressing S1 (Switch) discharges C1 and lights LED 1 (and LED 2 briefly).
* C1 then charges through R4.
* As the charge on C1 passes 3 and 6 volts, LED 2 and 3 glow in sequence.
* Reduce R2 to balance time delay sequence and reduce the delay time.
* Delays shown will vary with a tolerance of C1.
Need to use the following IC components:
· LM1458
· 2N2222
· 1N914
The power supply of the circuit is 9V DC
LED 1 is Red LED
LED 2 is Green LED
LED 3 is Blue LED
You need to use and calculate the values of the following components for the circuit.
Ø Potentiometers, or Variable Resistors
Ø Resistors
Ø Capacitors

Help would be appreciated.

Thank you,

 

That isn't a question (in the context of this forum). It's a statement of the problem you need to solve. You need to ask specific questions about the specific points you are stuck at.

Remember, this is YOUR homework and the more assistance you receive, the less you learn (to a point). So show your best attempts, no matter how right or how complete, and then ask questions about what you believe is preventing you from going further. We'll provide feedback, hints, and suggestions to help you get past that point and move forward.

 

Your spec talks about "a comparator" (singular). The LM1458 is a dual opamp. Are you allowed to use both opamps (i.e., two comparators)?

Are you given a circuit diagram of any kind? Odd that they are talking in terms of a circuit's reference designators if there's no circuit. But they could just be wanting you to use those specific designators in your circuit for the components that perform those functions.

 

Your spec talks about "a comparator" (singular). The LM1458 is a dual opamp. Are you allowed to use both opamps (i.e., two comparators)?

Are you given a circuit diagram of any kind? Odd that they are talking in terms of a circuit's reference designators if there's no circuit. But they could just be wanting you to use those specific designators in your circuit for the components that perform those functions.

 

No, I don't have any circuit diagram. I need to design a circuit for this. In question, it is mentioned to use LM1458. I am confused and not really sure how to start. Can you provide some idea so I can dig in further?

Thanks,

 

No, I don't have any circuit diagram. I need to design a circuit for this. In question, it is mentioned to use LM1458. I am confused and not really sure how to start. Can you provide some idea so I can dig in further?

Thanks,

Coming up an idea is pretty clearly part of the intent of the problem, so it wouldn't be proper for us to furnish you with a bunch of ideas. Talk to you instructor on that score.

But an idea on how to start organizing your thoughts, the problem talks about using a switch to discharge a capacitor and then the capacitor charges via a resistor. So sketch what the voltage on the capacitor will look like as it charges toward 9 V.

You are told to use an opamp but the problem talks about comparators. You might look into whether or not an opamp can be used as a comparator and, if so, how.

That should give you plenty to look into for starters.