hello, please lend me help calculate lpf for simple non inverting op circuit.
r1- 22ohm
r2- 2200ohm
roll off -40khz
need cap value for parallel r2.
thank you for formular and answer if possible. 😀
r1- 22ohm
r2- 2200ohm
roll off -40khz
need cap value for parallel r2.
thank you for formular and answer if possible. 😀
I think you have other problems before wondering about the cap value.
What opamp would this be ? The gain is through the roof at >2000 and so most opamps would be rolling off before 40kHz anyway. There would also be very real issues with DC offset for most opamps.
Do you need that gain ? or is it a mistake in the diagram 🙂
What opamp would this be ? The gain is through the roof at >2000 and so most opamps would be rolling off before 40kHz anyway. There would also be very real issues with DC offset for most opamps.
Do you need that gain ? or is it a mistake in the diagram 🙂
The noninverting amp has always at least a gain of 1. R1 is a bit low (OPamp must drive the current through R1)... use C2=1/(2*pi*40e3*R2), C2=1.8 nF is a good Value Greetings,Udo
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Gain at ~1,000, so you need a 40MHz GBP from the opamp, I don't think TL081 is going to do it (The large signal differential gain vs frequency curve on the datasheet is informative).
Also those opamps are not well behaved with low Z loads, something to think about.
Regards, Dan.
Also those opamps are not well behaved with low Z loads, something to think about.
Regards, Dan.
Lol... start again, my mistake.
Gain is (2200+22)/22 which is 101
You need around 2.2nf across R2 for it to be 3db down at 40kHz. When you are running such high gains (and 101 is high for a single opamp like the TL0 series) then the cap value can't be calculated exactly because the opamp has influence as well.
Gain is (2200+22)/22 which is 101
You need around 2.2nf across R2 for it to be 3db down at 40kHz. When you are running such high gains (and 101 is high for a single opamp like the TL0 series) then the cap value can't be calculated exactly because the opamp has influence as well.
The TL081 only specifies a 3MHz GBP so even at the reduced gain you still need more opamp....
Use a TL082, split the gain into two stages and tings will be better behaved.
Regards, Dan.
Use a TL082, split the gain into two stages and tings will be better behaved.
Regards, Dan.
hello, already use tl081 in circuit. i adjust gain can. no problem. sound ok, but bright. what gain, resistor value should go for? i need highest possible, but well behave. also lpf still 40khz 😀
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