I have a very basic understanding of op-amps and when I look at schematics I see less standardized usage of them than say a 12ax7 tube. Generally with a preamp tube, there's a plate resistor, a cathode resistor, a coupling cap, a grid resistor and cap on the input to block DC, and you see that everywhere.
Is there a similar "standard" way to wire an opamp as a gain stage (say while using the inverting input of the opamp as signal in and with a dual supply voltage for example)?
Is there a similar "standard" way to wire an opamp as a gain stage (say while using the inverting input of the opamp as signal in and with a dual supply voltage for example)?
Ok thanks! So that would be 5x gain, no filtering, inverted signal, and the 0.1uFs are HF noise rejection?
Yes, the values of the resistors can be changed (keeping the same ratio),
and still give the -5 gain factor. Or another ratio can give a different amount of gain.
But the input resistor is the circuit's input impedance, so it should be high enough
not to tax the signal source. Usually 10k is fine. If the source is another opamp,
the input resistor could be lower. Some op amps can drive as low as 600R. Smaller resistor
values tend to improve the high frequency bandwidth, especially for the feedback resistor.
The bypass capacitors help the op amp be stable, and also prevent the inductance
of the power supply leads from causing ringing at the op amp supply pins. Always use them,
mounted close to the op amp supply pins, with short leads.
Sometimes a small series resistor, around 100R or so, is added at the op amp's output
to improve its stability into capacitive loads. This can be done because the normal load
is much larger than 100R.
and still give the -5 gain factor. Or another ratio can give a different amount of gain.
But the input resistor is the circuit's input impedance, so it should be high enough
not to tax the signal source. Usually 10k is fine. If the source is another opamp,
the input resistor could be lower. Some op amps can drive as low as 600R. Smaller resistor
values tend to improve the high frequency bandwidth, especially for the feedback resistor.
The bypass capacitors help the op amp be stable, and also prevent the inductance
of the power supply leads from causing ringing at the op amp supply pins. Always use them,
mounted close to the op amp supply pins, with short leads.
Sometimes a small series resistor, around 100R or so, is added at the op amp's output
to improve its stability into capacitive loads. This can be done because the normal load
is much larger than 100R.
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The point of an operational amplifier is that it will do "any" operation depending how you rig it up.
But the more commonly useful rigs will be in here:
Op Amps for Everyone -- R Mancini
https://web.mit.edu/6.101/www/reference/op_amps_everyone.pdf2MB PDF fileDon't skip chapter 2!! I find that most learners are confused not by the tube transistor or chip, but because they have not digested basic resistor networks and voltage sources.
That + 1000
Tubes are way too limited in what they can do, while Op Amps are "universal", you can do almost anything by using the proper NFB network or combining them in lots of ways.
To boot they are small, cheap, and easy to feed,what´s not to like?
EDIT:
You CAN build a 12AX7 based Op Amp, and in fact original ones were such ..
Notice the +/-300V rails.
That´s a flaw, not an advantage.
Tubes are way too limited in what they can do, while Op Amps are "universal", you can do almost anything by using the proper NFB network or combining them in lots of ways.
To boot they are small, cheap, and easy to feed,what´s not to like?
EDIT:
You CAN build a 12AX7 based Op Amp, and in fact original ones were such ..
Notice the +/-300V rails.
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