lol ahh i see Vout/Av So 80mv/10= 8mV!And another mistake.
I'll let you figure this one out.
Amplifiers! Who can help?
- Thread starter Ross44
- Start date
Good! Dig in and try even if you aren't sure you've got it down.
The idea is right, but the wording could be better. Attenuation is simply when the magnitude of the gain is <1. So a gain of 0.5 is an attentuation, while a gain of -50 is not.
When you convert to dB, THEN an attenutation is negative. Oh, and a subtle point that has been brought out is that gain in dB is ALWAYS based on the magntidue of the gain, which comes directly from the fact that the voltage is squared to convert it to power.
Something should have been screaming at you right here!
Av = Vout/Vin
Vin = Vout/Av
Vin = 80mV/10 = 8mV
It will take time and effort to get there, especially if your instructors don't care about enforcing units (which most, sadly, do not), but it's pretty clear that you did the calculation at one point correctly, probably on a sheet of paper somewhere, and then just wrote down the wrong expression here. That happens. But it also happens that you will make such a mistake before doing the calculation and proceed to get 0.25mV unless you are working the units, and not just tacking them on at the end based on what you expect them to be.
You definitely took the long route on the first one, but I addressed that in the prior post.
I would now like to learn about Non inverting amplifiers.
What i know.
i know that the input signal is effectively used as the reference voltage at the non-inverting input of the op-amp while the inverting input is indirectly referenced to ground. In order to keep the two input voltages to the op-amp the same, the amplifier must set Vout to whatever voltage is required to make the feedback voltage to the inverting input match the input voltage to the non-inverting input.
The idea is right, but the wording could be better. Attenuation is simply when the magnitude of the gain is <1. So a gain of 0.5 is an attentuation, while a gain of -50 is not.
When you convert to dB, THEN an attenutation is negative. Oh, and a subtle point that has been brought out is that gain in dB is ALWAYS based on the magntidue of the gain, which comes directly from the fact that the voltage is squared to convert it to power.
Something should have been screaming at you right here!
Av = Vout/Vin
Vin = Vout/Av
Vin = 80mV/10 = 8mV
It will take time and effort to get there, especially if your instructors don't care about enforcing units (which most, sadly, do not), but it's pretty clear that you did the calculation at one point correctly, probably on a sheet of paper somewhere, and then just wrote down the wrong expression here. That happens. But it also happens that you will make such a mistake before doing the calculation and proceed to get 0.25mV unless you are working the units, and not just tacking them on at the end based on what you expect them to be.
You definitely took the long route on the first one, but I addressed that in the prior post.
Thank you! its because i really want to understand these things. i came in this forum knowing nothing about and now nowing a fair share enough for me not to worry too much about pressure in my exam. Thank you for your great help.
I would now like to learn about Non inverting amplifiers.
What i know.
i know that the input signal is effectively used as the reference voltage at the non-inverting input of the op-amp while the inverting input is indirectly referenced to ground. In order to keep the two input voltages to the op-amp the same, the amplifier must set Vout to whatever voltage is required to make the feedback voltage to the inverting input match the input voltage to the non-inverting input.
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