what’s the difference between analog and digital electronics?

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what’s the difference between analog and digital electronics?

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Digital electronics just knows binary states, voltage on or off.
Analogue electronics works with variable voltage in certain limits.

Analog generally refers to a circuit where the response to an input is continuous.

Digital circuits have outputs which are discrete.

For example I have a circuit which measures the brightness of a light and outputs a voltage between 0 and 3v. The analog version can output any voltage between 0 and 3 depending on the brightness. The digital version can only output 0, 1, 2 or 3 volts. The steps could be much much smaller but there will always be discrete steps.

At the fundamental electric component level, the components themselves are analogue. (Unless we go to the real extremes of things activated by one electron). Digital circuits use the components in highly non-linear ways or use components with very high gain to mean the voltage can only be maintained as high or low.

For example an analog circuit might contain an amplifier which runs off a 10v battery with a gain of 3. I input a voltage of 2v, I’ll get a voltage out of 6v.

The digital version might configure the same amplifier with a gain of 1 million. If I apply 0v I’ll get 0v out, and if I apply 1, 2 volt or 9 volts I’ll get 10v out because that the maximum supply voltage. Technically if I feed a signal of 0.000001 volts then the amplifier will output 1v, but for all practical purposes the circuit is only capable of outputting 0v or 10v.