| Electronics > Beginners |
| Op amp basics |
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| Mr D:
Hi folks, Taking my first look at op amps, many questions spring to mind. But let's start with the basics. Below is an GIF for your inspection. I'm trying to get my head around the signal flow in this simplest of all op amp circuits. Ok, so in the real world, the op amp has power leads coming in and out of it, which are not shown on the diagram. In this circuit, because the difference in voltage across the signal pins is great, the op amp is setting it's output voltage as high as possible, because that's what it's designed to do. What i don't understand is: the circuit actually shows current flowing from the output down to ground. But how do I / we know where that ground is connected to with regard to the invisible power source that is supplying the op amps power? That ground must be connected somewhere to the invisible power source, otherwise no current would flow, right? But maybe it's connected to the op amp power source's positive terminal, in which case no current would flow??!! |
| malagas_on_fire:
well that looks like a voltage to current conversion topology, but i might be wrong since i've rebooting electronics aka, learned electronics but went to the firmware path .. so going back to basics has well How about some first steps into opamps principles ? https://www.analog.com/media/en/training-seminars/design-handbooks/Basic-Linear-Design/Chapter1.pdf Well current flows to the easiest path to ground :P Not the high impedance inputs , not to the power source , unless apply a load such a LED :D |
| xavier60:
That is not a practical op-amp application. There is supposed to be another resistor between the Inverting input and ground, not a wire. The inputs should be close to the same voltage, the op-amps output controlling the voltage on the Inverting input via the feedback path. |
| Nerull:
Simple opamp models often have 'assumed' power supplies. I believe it can be configured in everycircuit and defaults to a +/- 15V split supply, which means your positive rail is connected to +15V relative to ground and your negative rail is connected to -15V relative to ground. If ground (0V) was connected to the opamps positive rail, than the opamp could only output negative voltages. That yours is outputing 10V tells you it is not. |
| MarkF:
Here are some basics |
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