Hardware The computer program introduces a 15 second delay between the response to Question 3 and activation of the syringe driver. During this time the procedure can be stopped and restarted by further keypresses or mouse-clicks (see setup instructions for each version). A print current page signal is then sent to the syringe driver interface which closes the circuit between a 12 V regulated power supply and a standard car tyre compressor. Compressed air drives open an empty syringe mounted back to back to the delivery syringe, both of which are kept aligned by placement inside a clear plastic cylinder, mounted on a baseplate. The diagram shows a single such syringe driver. Two additional syringe drivers for the additional drugs are mounted in parallel on the same baseplate, with the pressure relief opening at the end of the travel of the first being connected to the inlet of the second, and so to the third. At the end of travel of the third driver syringe, excess pressure is released until the timer on the switching interface expires. The timer has 3 dipswitch settings for increments of 4, 2 and 1 minute, allowing the compressor to be set to run for 1 to 7 minutes, depending on requirements. In the multiple syringe arrangement, all 3 delivery syringes are connected by a 4 way junction to the single canula, so the drugs are delivered in succession, with no significant mixing in the canula itself.   The device components The following diagrams show the circuitry used in the syringe driver switching interface. Dr Philip Nitschke with the complete system in portable carry-case