I have been reading a little about biasing an opamp in class A,and as I understand it you have to use a resistor according to the output load,but what if i use different loads on the output for listening test and other,will a CCS solv this problem?And how do I construct this ? "never done sommething like this before"
You can buy a monolithic current source, or you can make one
easily enough. Try a resistor first, just for kicks.
For Class A, usually you want the bias to be as high as the
current to the load. For a resistor, this is easy - just use a
value (usually to the negative rail) the same value as the load.
Usually something like 10 K will do the job fine.
easily enough. Try a resistor first, just for kicks.
For Class A, usually you want the bias to be as high as the
current to the load. For a resistor, this is easy - just use a
value (usually to the negative rail) the same value as the load.
Usually something like 10 K will do the job fine.
Since the person asking the question was from Sweden, just one
word of caution. Those monolithic current sources (constant
current diodes) that are easily available in Sweden (ie. at Elfa)
are spec'd for a minimum voltage drop of 10V. Hence they may or
may not work depending on the op amp supply voltage and the
signal amplitude. Discrete CCSs can be built to work with smaller
voltage drops.
word of caution. Those monolithic current sources (constant
current diodes) that are easily available in Sweden (ie. at Elfa)
are spec'd for a minimum voltage drop of 10V. Hence they may or
may not work depending on the op amp supply voltage and the
signal amplitude. Discrete CCSs can be built to work with smaller
voltage drops.
Although it depends on OpAmps circuitry, the current source (sink) from output to -Vs (negative supply rail) does usually the job.
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