The line release knot is a simple "free" way to release your main fishing line from a trolley, or balloon, this knot can be used in some cases were out riggers, or down riggers are used but you must experiment with knot tension, and line diameter of the knot line, as these will determine how much pull it takes to release the main line.

A bite is taken in the fishing line (shown in blue) at the point where you wish it to be held to the trolley or balloon, and placed on the top of the EZ knot, then with a separate piece of line (shown as white) the EZ knot is tied around the fishing line.  the knot is pulled up as tight as you desire for the release,, a bit of practice is needed to get the proper tension in the release.  On the separate piece of line a snap can be attached for sliding down a trolley, or if you like a simple paper clip works great for this, and is disposable.  When using a balloon you can tie the balloon straight to the separate piece of line.  When the knot is completed you will have a loop of the fishing line hanging from the knot.  this will pull through the knot to release your main line.
This loop size can be adjusted after the knot is tied, rember , that as the end of the loop, starts passing through the knot, it will increase the resistance because of the bend being forced into the fixed diameter knot.

When using outriggers, and down riggers, and you need a release (because you have lost the standard line release) you can use a lite fishing line that breaks to release the fishing line, doing this tie the light line directly to the fishing line using the drop leader rigging shown else where on this site, I have also used rubber bands for this.