A Tobin mine was a space mine created by the now extinct Tobin civilization to protect their home planet.
The Tobin mines were intelligent space mines which were difficult and dangerous to handle. Touching them was out of question since it could trigger an explosion. The only place on the mine which could be touched was the underside of the mine, which contained the control area.
The mine had sophisticated inertial engines which were unaffected by gravitational conditions. This caused them to constantly reposition themselves randomly in space around the planet. They were programmed to hone in on a wide variety on energy signatures including Goa'uld weapons fire.
Reprogramming the mines could be done by entering a color-coded combination in the control area. If the wrong code is inserted, the mine would explode after five minutes if the right code isn't entered.
The mines were created by the Tobin whose civilization began on Earth but who are extinct now since several centuries. Their minefield containing hundreds of thousands of these mines however survived over time.
In the year 2000 the minefield in the Tobin system was chosen by the two Goa'uld System Lords Apophis and Heru'ur as the meeting place to discuss an alliance. Since the mines would attack their ships if they would fire, none of them could destroy the other. The Tok'ra however got to know about the meeting and decided to reprogram one of the mines which would then attack Apophis' ship, since one of their agents on board would activate a signal. This would cause a war between the two.
Luckily for them they had found the technical manual for the mines but since it was written in a Phoenician-like text, none of them could translate it. Because of this Jacob Carter decided to enlist the help of SG-1. After informing them about their plan they went to the Tobin system in a Tel'tak and were successfully able to reprogram a mine. Afterwards all went as planned but since Apophis took a whole cloaked fleet with him, he could escape after he destroyed Heru'ur's ship, since his fleet protected his ship. (SG1: "The Serpent's Venom")