Abstract: A rocket firing system comprises a magnetic core, a co-axial driver coil and a sensor coil or coils which are connected to a detector device which detects the presence and the desired state of a further coil which is inductively linked to the magnetic core. In use a low-power signal voltage is first applied to the driver coil. Subject to the detector device indicating the presence and desired state of a firing circuit of a rocket including the further coil, an operating power voltage is then applied to the driver coil to induce a firing voltage in the firing circuit.