I know the formulas, to some extend what impedance is. But i guess i would like to know what it really means in real world and how to use it/match it or manipulate it.(adsbygoogle = window.adsbygoogle || []).push({});

Please help correct my understanding or increase it. :)

High impedance is like high resistance and vice versa. You want low impedance to ground to remove noise for example. Which is why people put caps to ground because it removes high frequency noise/oscillation (ie: high f and fixed C makes low Z)

Now on some ic's, take op amp for example it has high input impedance. Is this to limit current and preserve the signal?

I've always thought that even when we connect two device together, we want to match the impedance to maximize signal transfer. If one is at 1000Ohm and the other at 50 Ohm, we don;t want to use resistor (because we lose the signal in terms of heat?) but use caps/inductor provided we know the freq? (how does this work over a variable frequency?)

The other thing is, why high impedance and low impedance on some equipment, ic's etc. Someone mentioned that BJT's have low input impedance (I suppose because they use current to turn on/off unlike mosfet which i would think have high input impedance?)

The other day i was trying to measure some voltage on my thermocouple, and the reading that come out did not correlate with the spec of thermocouple. It was indeed increasing/decreasing but was not linear with temperature. In fact, the numbers were all off (ambient temp came up with voltage reading when referred to spec equivalent to 60C etc..) Now i think this has something to do with impedance because i just connected directly to the meter. What is the proper way then to match it?

Are impedance most significant when it comes to small signal? When to consider and how to use it. Just wanting to increase my understanding.

Thanks

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# Understanding impedance

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