I used to have a software where you could virtually create an electronic circuit and test it. I am drawing a blank and cannot think of the name. Anyone remember / use the software ?? What was it called ?? Is there something similar ??

Testing an electroic circuit, something like a transistor circuit or a light signalling circuit ect.

I installed a software that let me use the PC as an oscilloscope , but
it does not mention how to connect the circuits to be tested with the computer an through which port.Does anyone lead me?
I mean how can I connect that cable to
the circuit ?

This is an important action when checking the circuit performance for analysis or when you repair a circuit/electronic device.

When testing circuits you often need to find the voltages at various points, for example the voltage at pin 2 of a 555 timer chip. This can seem confusing – where should you connect the second multimeter lead?

Measuring voltage at a point

• Connect the black (negative -) lead to 0V, normally the negative terminal of the battery or power supply.
• Connect the red (positive +) lead to the point you where you need to measure the voltage.
• The black lead can be left permanently connected to 0V while you use the red lead as a probe to measure voltages at various points.
• You may wish to fit a crocodile clip to the black lead of your multimeter to hold it in place while doing testing like this.