EC Resistor

An object you may not use often , but it's useful.
A resistor is a two terminal electrical component that implements electrical resistance . This one is 'electrically controlled ' with an input for that control.
For control I used the 'jumper' . It will give a constant signal that you set with the cog icon.
Here I set it on 0.5 or half.
One battery turns two wheels , but on the left is the EC resistor with the .5 setting. The wheel speed is half because the EC is wired in the power path.
Hope this helps some and ask if you have questions :)
Two things to help learn signaling.
1- make the 'debugger' your new best friend.
2- think like an electron . :)