Abstract: A detonator control circuit, principally for use for setting off an explosive charge, but other applications include, e.g., setting off a burglar alarm. The circuit includes a D.C. source, a first thyristor connected in series with the source and a detonator or alarm bell, etc. and a second thyristor connected in a triggering circuit. The control circuit is primed by causing the second thyristor to conduct and thereafter is kept in a state of readiness for allowing the first thyristor to conduct when required and detonate an explosion or ring the bell, etc.Preferably an indicator lamp shows that priming is taking place successfully and when it goes out the circuit is ready.