Electronic delay detonator

An electronic delay detonator circuit for igniting a plurality of serially connected detonators comprising:

• first and second power input lines;
• a diode bridge circuit having a first pair of opposite junctions connected between said first and second power input lines and a second pair of opposite junctions providing a bridge connection with said first pair of opposite junctions;
• storing means, connected between said second pair of opposite junctions of said diode bridge circuit, for storing electrical energy supplied from said power input lines;
• delay means connected between said second pair of opposite junctions, for producing an output when energy stored in said energy storing means reaches a predetermined amount;
• means for igniting one of said serially connected detonators in response to said output;
• and
• a resistor connected between said first pair of opposite junctions, and in parallel with said first and second power input lines, said resistor having a constant resistance substantially larger than an internal resistance of the electric circuit of said electronic delay detonator so as to dissipate stray current and allow counting of a number of said serially connected detonators.

A method for testing connection of electronic delay detonators, comprising the steps of:

• (a) providing a desired number of electronic delay detonators;
• each of said electronic delay detonators comprising first and second power input lines for externally receiving electrical energy, storing means connected to said first and second power input lines for storing the electrical energy, prevention means connected between said storing means and said input lines for preventing said stored energy from being released, delay means connected to said first and second power input lines for producing an output when the energy stored in said storing means reaches a predetermined amount, switching means responsive to the output of said delay means for momentarily supplying the electrical energy of said storing means to an ignition resistor, and a bypass resistor connected between said first and second power input lines and having a predetermined constant resistance distinguishably larger than an internal resistance of the detonator switching circuit in a non-actuated state and smaller than a predetermined value;
• (b) serially connecting said first and second power input lines of said detonators so as to form a blasting detonator circuit connection;
• (c) measuring a series resistance of said blasting detonator circuit connection in the non-actuated state;
• and
• (d) determining a status of connection based on the measured resistance relative to the predetermined constant resistances of said bypass resistors.