Claims
- 1. Apparatus for testing the ignition coil/capacitor combination of an internal combustion engine comprising:
- circuit means adapted for connection to the low side of the ignition coil to provide a cross-over signal manifestation of the zero cross-overs of the low coil ringing voltage;
- means connected to said circuit means for providing a signal manifestation of the number of zero cross-overs in the low coil ringing voltage; and
- means connected to said circuit means for providing a signal manifestation of the peak voltage of the low coil ringing voltage being above or below a given threshold voltage.
- 2. Apparatus according to claim 1 wherein said means for providing a signal manifestation of the number of zero cross-overs of low coil ringing voltage comprises a squaring amplifier connected to said circuit means for providing a square wave having transitions concurrent with the zero cross-overs of the low coil ringing voltage.
- 3. Apparatus according to claim 1 wherein said means for providing a signal manifestation of the number of zero cross-overs of the low coil ringing voltage comprises:
- a retriggerable monostable multivibrator and a delay circuit both connected to said circuit means, the output of said delay circuit being connected to and enabling operation of said retriggerable monostable multivibrator following the period of delay thereof from one of said cross-overs; and
- accumulating means responsive to the on condition of said retriggerable monostable multivibrator and to said circuit means for providing a signal manifestation of the number of cross-overs of the low coil ringing voltage.
- 4. Apparatus according to claim 3 wherein said accumulating means comprises:
- a second monostable multivibrator responsive to said low coil ringing voltage to provide a pulse of a given duration in response to each pair of zero cross-overs; and
- integration means responsive to the pulses of said second monostable multivibrator for integrating the voltage output thereof over the number of pulses provided thereby, thereby to provide a DC voltage proportional to the number of cross-overs of said low coil ringing voltage.
- 5. Apparatus according to claim 4 wherein said threshold means comprises:
- a threshold detector;
- and further comprising:
- digital processor means for providing manifestations of the normal or abnormal condition of said coil/capacitor combination; and
- means including an analog to digital converter responsive to said integration means and to said threshold detector to provide to said digital processor digital manifestations of the number of zero cross-overs of the low coil reinging voltage and of low coil ringing voltage being above or below said given threshold voltage.
- 6. Apparatus according to claim 3 wherein said accumulating means comprises a gate circuit connected to the output of said retriggerable monostable multivibrator and to said low circuit means to provide a train of pulses, one for each pair of zero cross-overs of the low coil ringing voltage; and
- a digital counter responsive to the output of said gate circuit to advance by one count once for each pair of zero cross-overs of a given direction.
- 7. Apparatus according to claim 1 wherein said threshold means somprises:
- a threshold detector; and
- a voltage divider connected to a low side of the ignition coil, a tap on said voltage divider being applied to the input of said threshold detector.
- 8. Apparatus according to claim 7 wherein said voltage divider tap is adjustable to provide the input to said threshold detector at different voltage division ratios.
CROSS REFERENCE TO RELATED APPLICATIONS
The subject matter hereof is also disclosed, and some of it is claimed, in a commonly owned copending application entitled IGNITION ANALYSIS, Ser. No. 534,337 filed on even date herewith by Anthony J. Fastaia and Larkin M. Hasbrouck.
US Referenced Citations (4)