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A recommended free online schematic creator ????

gelpack

Jul 7, 2022
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I've been looking for a free online one of these. I tried the LTSpice modeller first that was suggested for modeling which is ok but does not really fulfill what I need in terms of straight schematics rather than modelling, as there are no connectors for example that I can find at least.

I then tried Digi key which seems ok, but all the connectors don't match up with the number of pins on the drawing object and I cant find a way to make them, so for example a 15pin male connector single in line has 17 pins on it shown on the schematic.

Also, you cant create a composite object for example I want to represent some components on the inside of a keyboard and its 2 * 15 pin connectors, so this would require a rectangle, some connectors and a few components inside, this indicates its inside the keyboard and is clear. Then on the exterior of this box are all things which connect to it for a test rig, get where I am coming from.

I'm probably doing something wrong , and its simple stuff, so nothing complicated, so I thought ( Light bulb moment ) why don't I ask the professionals here for advice, I'm sure there are some of you using something like this already.

Cheers - Terry
 

Alec_t

Jul 7, 2015
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as there are no connectors for example that I can find at least.
You can easily make your own in LTS. Copy any .asy file and double-click the copy to open it in the LTS editor. Then edit away using the Draw/Delete/Move tools.and save the edited version in the appropriate sym folder under a new name.
 

gelpack

Jul 7, 2022
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You can easily make your own in LTS. Copy any .asy file and double-click the copy to open it in the LTS editor. Then edit away using the Draw/Delete/Move tools.and save the edited version in the appropriate sym folder under a new name.

:) - Wilco - Thanks
 

Alec_t

Jul 7, 2015
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I've just remembered it's actually simpler just to fire up LTS and click File/New symbol to open a blank canvas for a custom symbol.
 

gelpack

Jul 7, 2022
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:) - Wilco - Thanks

Hey Alec,

I gave it a try, I cant say its that user friendly to be honest, but yes I was able to create a very basic component. I don't have too much time to research it right at the moment today, but I will come back later, however what I found was I could not create any attachable nodes which wires can lock onto, so if I create my component and add lines ( drawing lines ), then add the symbol to a schematic, I can draw the wire to the connector lines but the symbol can be moved but the wires stay put on the schematic which is not the way it works for example with a transistor of voltage source which is inbuilt.

I guess what I am looking for is a component with say 15 pins and some internal components such as LED's and push buttons, these would form part of the overall schematic which connects through the peripheral of the component via wires.

This is obviously possible as components already exist like that, the question is as to if it is possible to do it yourself. I'm sure it is, I just cant see it on the face of it right this moment.


Cheers - Terry.
 

Harald Kapp

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I guess what I am looking for is a component with say 15 pins and some internal components such as LED's and push buttons, these would form part of the overall schematic which connects through the peripheral of the component via wires.
That is not called a component, it is called a subcircuit. See here how to create and use a subcircuit.
 

Alec_t

Jul 7, 2015
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I've attached a connector symbol .asy file for you (rename it by deleting the .txt extension)
I created it by :-
1) drawing a schematic with just ten labelled nodes 1-10 (as per the connector.asc attachment),
2) using the Hierarchy tool to let LTS create its own symbol (as per the con1 image).
con1.jpg
3) using the Edit Attributes tool to set the Prefix to X,
4) using the Move/Draw/Delete tools to position the nodes to my liking and draw a new rectangle round them,
5) saving the edited symbol (as per the con2 image) in my .....Documents\LTspiceXV11\lib\sym\misc folder.
con2.jpg
You can place this symbol in a schematic then right-click it to edit it to your liking (e.g. add extra nodes or delete some). There is no model file associated with this symbol.
 

Attachments

  • Connector.asc
    373 bytes · Views: 1
  • Connector10pin.asy.txt
    758 bytes · Views: 1

73's de Edd

Aug 21, 2015
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Why for is it 1-10-2-3-4-5-6-7-8-9 ?
and the I.C. numbering after pin 5, should cross over and continue CCW as pins 6-10.
Plus, who is your supplier if 10 pin I.C.'s ?
 

Harald Kapp

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Is this what you want?
upload_2022-7-11_13-4-8.png

To the left is a circuit with a sine voltage.
In the center is a subcircuit with a simple RC filter. This subcircuit has the symbol to the right.
The symbol is used in the left circuit.
The result of the simuation is on top with V(n001) being the input voltage, V(output) being the output voltage with the expected phase shift.

Using this kind of subcircuit can hide the complexity of the subcircuit on the top level of the circuit schematic. It also allows to re-use the subcircuit multiple times without having to draw it multiple times.
The set of design files is attached in the example.zip archive.

Addendum: You do not need the connectors and wiring between the subcircuits as separate components. The connection is made within LTSPICE by the named input/output/common port symbols.
 

Attachments

  • example.zip
    829 bytes · Views: 0
Last edited:

Harald Kapp

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If yu only want to draw a schematic without simulation, try e.g. CircuitLab or KiCad.
CircuitLab is easy to use but limited.
KiCad is powerful but has a steep learning curve.
 
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