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song123 Post subject: OP amp design Posted: Sun Sep 18, 2005 10:59
am Hi everyone, I am going to design a zero crossing detector
with using an op amp. Then, I found a basic circuit from internet
that the circuit uses voltage divider from the main source (230 V) as
as input voltage (V+) for the op amp. One thing that
I am not sure is, why it uses coupling capacitor instead of resistor
in the voltage divider ? What is the advantage of it ? Ok. Thank
you in advance. Top song123 Post subject: Posted:
Sun Sep 18, 2005 11:10 am Sorry for the small image. Here I make
it bigger. Thanks. Top Guest Post subject:
OpAmp QuestionPosted: Mon Sep 19, 2005 11:53 am It's a matter of
numbers. Resistors convert power=current*voltage into heat, capacitors
don't. Why waste power? Good Luck! Top
Guest Post subject: Re: OpAmp QuestionPosted: Mon Sep 26, 2005
11:25 am Guest wrote: It's a matter of numbers. Resistors
convert power=current*voltage into heat, capacitors don't. Why
waste power? Good Luck! Good Try.. The capacitor
removes any DC offsets from the generator and the 500k provides the
ground reference. Top Guest Post subject: Coupling
capacitorPosted: Wed Sep 28, 2005 5:44 pm In most areas, the 230
V mains voltage comes from a transformer. Since transformers do not
pass DC, there should be *NO* DC offsets on the incoming voltage.
A resistor would, in fact, work in the circuit where the capacitor
is shown. Good Luck! Posted
11/12/2012
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