Delay circuit for use in electric blasting system
US4984519A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Feb 13, 1989 |
| Grant date | Jan 15, 1991 |
| Priority date | — |
| Expiry date | Feb 13, 2009 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF42D1/055
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A delay circuit for use in an electric blasting system including a capacitor for storing electric energy supplied from an electric blaster, an actuation circuit for detecting the stop of voltage supply from the blaster to generate an actuation signal, a circuit for generating clock pulses, a circuit for counting a predetermined number of clock pulses in response to the actuation signal to generate an igniting signal, and a switching circuit for responding to the igniting signal to discharge the electric energy stored in the capacitor through an igniting resistor, the actuation circuit having a zener diode with a threshold voltage. When the voltage supply from the blaster is stopped and the voltage across the zener diode becomes lower than the threshold voltage, the zener diode is cut-off to generate the actuation signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.