Free EDA: Good looking schematics using TinyCAD

How to use TinyCAD, a free schematic capture software to draw professional looking electronic schematics with custom symbols.

Welcome to the second part of the Free EDA series. Now that we have a working circuit design, let's draw a good looking schematic. I decided to use for this the free schematic capture software called TinyCAD. It is available only for Windows but runs it Wine too.

I have chosen TinyCAD because it has quite powerful drawing abilities for a schematic capture software and I found it quite easy to make my own symbols. More than that, it can export netlists that you can use to design the PCB later (I will not be using this feature though).

I have tried TinyCAD before and I quit using it because I didn't like how the schematics look. There are plenty of libraries with many symbols, but there are also duplicate symbols that look different in other libraries. Some look good, some don't. I didn't actually start to use TinyCAD until I made my own libraries that I'm gonna share with you at the end of this post.

Let's start TinyCAD. The first thing to do is set up the grid (Options menu - Settings). It has two preset grids that are just OK. I recommend you use the Normal grid spacing for drawing schematics and the fine grid when drawing symbols. Here comes the first issue you will encounter with the normal grid and default libraries. Not all parts have pins that fall correctly on the grid. This was another reason to make my own libraries. The other issue you will encounter with the default libraries is that some symbols are too large in comparison to the others.

Setting the grid and a symbol that doesn't fit the grid

Before I start drawing my schematic, I must make a relay symbol. This is a good opportunity to learn how to add existing and create new symbols. If you choose Libraries from Library menu you'll be shown the list of all in use libraries. Double click on any to start editing symbols in it. Click the New button to create a new one. Click Add to add an existing one. I'll add the symbol into an existing library. Right click anywhere in the opened library to add a new symbol.

Add new symbol to library

It is very important to place pins on the normal grid and not the fine one! So anytime you want to place a pin switch back to normal grid, add it and adjust the symbol to fit. Or work with the normal grid and switch to the fine one only when needed. Here is a short video about drawing new schematic symbols:

Here is how my finished symbol looks.

TinyCAD relay symbol

I will draw the schematic of the dark activated switch I designed in the previous post. To add a symbol all I have to do is double click it in the left library view and the move the mouse cursor and click where I want to place it. A tool window is always on screen with the selected element's properties so I can edit name, value an other things. This is what I got in LTspice:

LTspice schematic

And this is what I get in TinyCAD.

TinyCAD schematic

There are some things to mention. TinyCAD is not perfect. The junction dots are not automatically placed as top layer and if you draw wires with a different color (like my schematic) you will see wires over the black junction dot. The only thing to do is Ctrl+click multiple junctions to select them and right click top bring them on top layer (Z-Order - Bring to front).

And another issue is how do you export the schematic as an image. TinyCAD has File - Export as image file. But here is what you get when you select color and black/white output:

TinyCAD image export

Any symbol that has a filled background turns to black when you choose the B&W output. Pins turn into small squares that are also visible on color output as gray squares. There are some workarounds like using hidden pins and drawing lines instead of them but I don't want this.

Instead I use a different method. I print my schematic to a virtual PDF printer. Then open the PDF with GIMP and import it as 150 DPI image with antialiasing. Then I export to PNG. The result is great. If I want B&W schematic I just change TinyCAD color scheme and put black all over. I don't worry because there's also a reset button there (Options - Colours).

Overall TinyCAD has some bugs but it is a good schematic capture software. It is very configurable and it is quite easy to create new symbols and manage libraries with it. As I promised here are my libraries: download. Just extract them anywhere you want and add them from the Libraries window.

What free software do you use to draw electronic schematics? Have you ever tried TinyCAD?