A Launch Controller should above all be safe, it should be designed with safety first and functionality second.

Due to the longer cables used with HPR rocket launch controllers it is in my opinion best to go with a relay controller with the battery at the rocket end of the cable this will ensure there is minimum voltage drop over the cable to affect the firing of the ignitor.

There are two thoughts on the use of a continuity check:

Firstly there should not be any continuity check as passing any current through an ignitor in the motor is dangerous as it may fire. Also if the continuity check circuit fails it may fire the ignitor.

Secondly the continuity check is ok if it is designed with safety in mind it should pass minimal current so as not to fire the lowest current ignitor. It should be designed so that if the circuit fails it fails to an open circuit so as not to fire the ignitor.

With a Relay controller it is a good idea to have a means to check that the firing relay has not stuck in the on position as it is possible for relays to stick.

The Relay launch controller I have designed in the homebrew section fulfills all of these requirements.