How do engineers figure out how to design circuits?

What I mean is ';how do they figure out what components to use and how to arrange them';?How do engineers figure out how to design circuits?
Engineers design circuits through trial and error.


The circuits that fail don't get used again.





It's been said that the best engineers never invent something, but only adapt existing designs to suit their need.





We also do lots and lots of reading...looking for how others have solved problems. (Perhaps also a bit of reverse-engineering.)





My personal motto: Experience gained is a function of quantity of equipment destroyed.





Edit: Apparently Sandip has never designed a circuit, because he claims to have never failed.





In today's design process, I agree that we design on paper or in simulations first, before procuring equipment and mobilizing personnel. However, even in this process, it is through trial and error that we determine which designs should proceed to the 'realization' stage. Then, we check the real implementation to confirm that our calculations, assumptions, and simulations were sufficiently accurate.





I personally perform enormous amounts of calculations and simulations long before hardware or coding implementation occurs. In power systems, things tend to go wrong in a big way if the design isn't sufficient. In some facets of electronics, it is easier and faster to breadboard the circuit than to go through a full simulation process. But when the costs of real failure are higher than the cost of calculations, simulations, %26amp; lab-scale tests, we do the calcs, sims %26amp; tests first.How do engineers figure out how to design circuits?
Circuit design is accomplished by using mathematical models of the circuits and books which contain the electrical characteristics of components. Typically you use circuits that are already known such as oscillators where you can. ( Why re-invent the wheel)





Bottom line at least for control systems is that a very long and complicated equation(s) are converted into a circuit.





It's all math.
I agree





But I'd like to add that component values are adjusted to meet the requirements of the job.





Also various circuits are combined to make a larger one.
Thank you mutan,





Circuits are not designed by trail and error, every component has a specific response to given input (the inputs may vary from DC, sine wave, Ramp or Pulse) considering this an equation is designed relating the input to the output.





Once this is done, they replace the parts with their mathematical counterpart. An engineer that has worked long enough in the field may be able to remember the response of pre-fabricated circuits such as Amplifier, Switch etc. and construct simple circuit in no time.
engineers can only design circuits from the rquirement of the job to be done. if a engineer needs to know what power supply is available e.g. AC or DC if he needs to convert the ac to dc or othere way around to give you a result. the result can be in a wave form or in a figure form. mainly what output is required. with out these requirement the engineers can not design a circuit. when designing a circuit the engineer is required to do all the calculation for commponents e.g resistors capcitors inductors op-amps or microchips for controls. to give you a required output.