Electronic explosives initiating device

An electronic detonator for initiating explosives which includes:

• a bridge firing element which is designed to be fired by a firing signal with a voltage which is greater than a designed no-fire voltage (V.sub.NF),
• a bi-directional communication circuit, and
• an operating circuit which is responsive at least to an operating signal at a voltage which is below the designed no-fire voltage (V.sub.NF), and wherein
• the bridge firing element can only be fired by a firing signal with a voltage which is greater than a no-fire confirmation test voltage,
• the no-fire confirmation test voltage is less than the designed no-fire voltage (V.sub.NF),
• the operating circuit is responsive to an operating signal at a voltage which is any voltage in a first range of voltages which straddles the designed no-fire voltage (V.sub.NF),
• the operating circuit, in response to an operating signal at a voltage which is in the first range of voltages and which is below the designed no-fire voltage (V.sub.NF), being capable of generating the said firing signal for the bridge firing element but at a voltage which is less than the no-fire confirmation test voltage, and
• the operating circuit, when connected to an operating signal at a voltage which is in the said first range of voltages and which is below the designed no-fire voltage, is in a state in which identity data, pertaining to the detonator, can be transmitted to or from the bi-directional communication circuit.