So I'm not entirely sure how to design this. Could anyone help me with the calculations needed to modulate as well as the circuit design? Please and thanks.
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Show what you've done so far.So I'm not entirely sure how to design this. Could anyone help me with the calculations needed to modulate as well as the circuit design?
HI Mr. Dennis,Show what you've done so far.
Don't expect anyone on this site to do your homework for you.
In your first circuit, you're not modulating the current in the LED.Put some effort in at your suggestion, and I also came up with this. Does this look ok to you?
Mr. Dennis,In your first circuit, you're not modulating the current in the LED.
In the second circuit, the power source and the signal generator will be fighting each other.
It would be helpful if you told us what types of circuits you've studied. Have you used opamps?
You're required to be able to show DC and AC current independently for your demonstration. Can you think of an opamp circuit that will allow you to do this?Yes I've worked with opamps, again not an expert on circuits so not too sure how that would play into this.
Mr. Dennis,You're required to be able to show DC and AC current independently for your demonstration. Can you think of an opamp circuit that will allow you to do this?
Could you post datasheets for the LEDS?
When is this assignment due?
Mr. Dennis,
It's due Monday so I have some time. I'm not quite following you there. I'm not sure how to utilize the OPAMP for this. Ya I'll send LEDs, hold on.
Thanks
Mr. Dennis,The LED data is for a random red LED:
View attachment 197828
You're going to need to know the forward voltages of the LEDs so you can determine LED currents.
A combination of that and Ohm's Law.Once you obtain forward voltage to get current do you just utilize Kirchoffs rule or?
Anyone have any thoughts on this?
1/2/3/4 This was something I found online for modulating LEDs. I genuinely had no idea how to do it otherwise, again not familiar with the term. If you know of a similar solution to this and could draw/explain it I'd appreciate it. Again spent quite a few days just googling/asking TAs and not getting other answers. Next monday I just need to show a circuit diagram and explain the design, trust me I have put some time into this project but again not making much progress. Thanks for taking the time to continue this conversation though, that means volumes tbh.Parts of the problem unclear to me.
- What is the purpose of the series combination of 100pF and 22 ohms in parallel with the 300 ohm resistor?
- What is the purpose of the coupling capacitor for the AC signal?
- Why are you using an inverting summing amplifier?
- Why are you using different gain for the AC and DC inputs?
- You forgot to label circuit ground.
- Why are you modulating the current instead of simply turning the LED on and off? Is it just a contrived situation to teach you how to do it?
- Were you given any requirements for the DC and AC currents?
I assumed you had to do it that way, how would you suggest using the second LED then
- Why are you thinking you have to drive both LEDs at the same time?
- Are you planning to use the same detector for both LEDs?
If you can talk to your instructor or TA, there's no need to make assumptions. If you couldn't ask questions, then you can simply state your assumptions as part of your solution.I assumed you had to do it that way,
Since the LEDs have different maximum currents, I'd make two variants of the modulate circuitry and do the experiment once for each emitter/detector combination.how would you suggest using the second LED then
What do you intend to do with the detector results? One LED is visible light and the other in infrared.Yes, but I believe we are given an additional detector.
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