What is the easy and most affordable way to design a circuit board for a product which I have in my imagination?

 

Draw the schematic using one of the many free programs, make a prototype to verify the design, design the PCB, and send it to a board house (or make it yourself).

 

Sir which apps is good for circuit design

 

Draw the schematic using one of the many free programs, make a prototype to verify the design, design the PCB, and send it to a board house (or make it yourself).

Yes

 

Sir which apps is good for circuit design

There are many available, some to buy and some for free.
Commonly used free ones are Eagle and Kicad.
Eagle is the one I use and it is a bit quirky and takes a while to get used to but it is very capable. The free version limits you to a board 100mm x 80mm and one schematic sheet.

 

Sir which apps is good for circuit design

LTspice is popular with members. I only started using it in the last year or so, and only because members were posting .asc files. I still prefer to do my analog designs the old way.

 

There are many available, some to buy and some for free.
Commonly used free ones are Eagle and Kicad.
Eagle is the one I use and it is a bit quirky and takes a while to get used to but it is very capable. The free version limits you to a board 100mm x 80mm and one schematic sheet.

I'm using the 7.7 version of eagle and it allows 2 schematic pages. Is the autodesk version (8.x) more limited? I fear they are moving to clamp down on the free version and perhaps eliminate it eventually.

If I was starting today, I'd go with kicad. It's got momentum behind it and, because it's open source, will probably not go the way of eagle. I'm looking at moving to Kicad because of the above concern. I don't trust autodesk.

 

+1 on Kicad.
Max.

 

LTspice is popular with members. I only started using it in the last year or so, and only because members were posting .asc files. I still prefer to do my analog designs the old way.

I've used LTSpice for years and think for general circuits its a good first step in the design process. There are lots of spice-based simulators out there, some more user friendly (maybe none less user friendly, lol). It certainly has a lot of user support behind it. I would never go straight to a PCB from spice, though. A good breadboard is an essential next step. Spice models are usually reasonable first order approximations but, especially for analog, they are no substitute for testing with actual components. And some spice models are just plain wrong.

DL324, maybe you could lay out your design process. I'm more of a digital guy and am always looking to learn from others, especially outside my core area.

 

Sir which apps is good for circuit design

There are several steps in the process and the tools you use depend on your own workflow. I'll share mine.

I like starting in LTspice as @dl324 mentioned. This is NOT for laying out your PCB. It's for drawing a schematic and getting a working simulation as a bonus. I'm reluctant to build something, even on a breadboard, if I can't show that it works in simulation.

My next step is a breadboard prototype. Translating from a schematic to a breadboard layout can be challenging and you can find tools that help with this by drawing out a breadboard layout. I just do it by hand.

If the breadboard circuit works and I want to commit it to a board, I draw out a perfboard layout using drawing software. I have a lot of prior experience with drawing programs and I find this easier than the dedicated programs mentioned by @AlbertHall . The downside to my approach is that my drawing is useless for sending to a shop to get a PCB manufactured. The dedicated PCB programs do auto-routing, have libraries of components, and can output a file that the shops can use to make a PCB. If that's your end goal, then I would recommend using one of those. I never go past a perfboard, so my approach works great for my uses.

 

I'm using the 7.7 version of eagle and it allows 2 schematic pages. Is the autodesk version (8.x) more limited? I fear they are moving to clamp down on the free version and perhaps eliminate it eventually.

AFAIK, nothing stops you from using an old version of Eagle freeware. I use Eagle 4.13r1 for most of my schematics and board layouts. I don't like the look and feel of the newer versions and don't care to re-do my library customizations. The only feature I like to see in my old version is the ability to have selective overbar in text.

 

AFAIK, nothing stops you from using an old version of Eagle freeware. I use Eagle 4.13r1 for most of my schematics and board layouts. I don't like the look and feel of the newer versions and don't care to re-do my library customizations. The only feature I like to see in my old version is the ability to have selective overbar in text.

The problem with sticking with older versions is using schematics and libraries from the newer versions. While I never trust components from the internet, they are useful starting places. I wind up redrawing a lot of them - if nothing else, fixing drill hole size and adding keepouts. I do like to look at schematics that companies and people post and learn a lot from them. (sometimes learn what NOT to do, chuckle).

I don't recall the differences between 4.xx and 7.7 but do like what's in the 7.x series. I have to say the 8.x stuff looks slick but the autodesk "two year free license" (or what ever it is, I disremember) makes me think they've got shoes lined up to drop.

 

I'll share the steps I use:

1. Conceptualize and sketch the circuit schematic on paper. Organize the circuit into functional blocks.

2. Draw schematic using software that incorporates simulation.
This may or may not be the same product used to for PCB design.

3. Simulate the circuit.
Simulate the circuit and make adjustments until the circuit provide a reasonable expectation of performance.
Having the circuit organized into functional blocks really helps this process.

4. Breadboard the circuit.
Breadboard, test, and refine the circuit until the circuit performs as desired.

5. Update the schematic to reflect the working circuit from step 4.

6. Transfer the schematic to PCB design software.
This may or may not require the schematic to be redrawn using the schematic capture program native to the PCB software.
Build any parts needed for schematic or PCB layout

7. Transfer schematic to PCB design

8. PCB Design - Place components

9. PCB Design - Route traces

10. Perform Design For Manufacturing check (DFM check)

11. Submit design to PCB Fab house.

These are just basic steps I try to follow