what is open loop analog circuit?

Answer 1

Analog circuits do not have discrete or set levels of voltages. 0 - 10 volt signal is from a potentiometer is analog (infinate resolution). A 0 - 10 volt signal from a digital to analog converter (like a CD player) divides the signal into a specific number of steps (for example 12 bit would be 4096 steps or 409.6 levels per volt).

Open loop describes a control circuit that does not have feedback to indicate what the end result of the control was.

For example, a DC motor being controlled with a 0-180 VDC rotor voltage that does not have speed feedback would be an open loop analog circuit. There is an expectation that the motor will reach half speed at 90VDC, but there is no measurement data with which to adjust the voltage if it doesn't.

Answer 2

It is one in which an analog signal is turned on a certain amount to make a larger analog signal turn on a corresponding amount, without any correction being made if they don't match well..

It is open loop because no measurement is made on the output signal to make sure it is really matching the input one. If it were closed loop you could keep correcting based on the measurements to make sure it is the output you want.

It is analog because the signals are values between the minimum and the maximum that are expressed as voltages, temperatures, pressures etc rather than as numbers ("half open" rather than "50%").

An example would be if you turned on a mix of the cold and the hot water for your bath and just let it run without touching the water in the tub to see if it became the temperature you wanted.

Answer 3

A control system e.g. electric circuit that does not have a feedback loop and thus is not self-correcting, do a quick search for "electronic feedback circuits" on google and you will lots of info, feedback is used in operational amplifiers to control gain and other characteristics