Electronic rodent trap with voltage booster circuit for improved trap performance over the life of the battery
A circuit and method for boosting the voltage input to the gate of a MOSFET switch used in an electronic rodent trap is provided. By boosting the voltage to the gate, the MOSFET can be fully turned on to activate an effective killing cycle in the electronic rodent trap even when the trap's battery voltage has dropped to a level that would otherwise be insufficient to fully activate the MOSFET.
1. An electronic rodent trap for electrocuting rodents comprising:
at least one battery;
a micro-controller powered by said at least one battery;
a circuit for boosting an output voltage of said at least one battery, said circuit including a multi-stage charge pump driven by a pulse train from said micro-controller and having outputs of each stage connected in series for generating an output having a voltage higher than said battery output voltage;
killing plates coupled to a transformer for electrocuting a rodent when activated; and
a drive circuit connected to the output of said circuit for boosting an output voltage of said at least one battery including said charge pump and to a high-voltage MOSFET coupled to the transformer, the MOSFET when turned on generating a high voltage by rapidly switching a ground return path of the transformer to create a flyback voltage that activates the killing plates, the higher voltage output of the charge pump fully activating the MOSFET even when the output voltage of the at least one battery has dropped to a level insufficient to fully turn on the MOSFET.
2. The electronic rodent trap as set forth in claim 1 , wherein the charge pump includes a plurality of diodes and a plurality of capacitors configured in a plurality of stages, each stage being driven in turn to add a voltage supplied to the micro-controller to the battery output voltage.
3. The electronic rodent trap as set forth in claim 2 , wherein the plurality of diodes are arranged in series.
4. The electronic rodent trap of claim 3 , wherein the plurality of capacitors are arranged in parallel, each capacitor connected on a first end to a respective input/output pin of the micro-controller and connected on a second end between an output of one of the plurality of diodes and an input of another one of the plurality of diodes.
5. The electronic rodent trap as set forth in claim 1 , wherein high-voltage MOSFET requires a gate voltage of approximately 5 volts to partially activate and 10 volts to fully activate.
6. The electronic rodent trap of claim 4 , wherein the first end of each of the plurality of capacitors is directly connected to a respective input/output pin of the micro-controller and the second end of each of the plurality of capacitors is directly connected between an output of one of the plurality of diodes and an input of another one of the plurality of diodes.
7. The electronic rodent trap as set forth in claim 1 , further comprising a voltage regulator arranged between the at least one battery and an input of the micro-controller for regulating a power supply voltage provided to the micro-controller.
8. The electronic rodent trap as set forth in claim 7 , wherein the power supply voltage is different than the battery voltage.
9. A battery-operated electronic rodent trap having a transformer coupled to killing plates, the trap comprising a MOSFET switch coupled to the transformer and a multi-stage charge pump driven by a pulse train that is generated by a micro-controller, the multi-stage charge pump boosting a voltage input to a gate of the MOSFET so that the MOSFET is fully turned on and a flyback voltage from the transformer, used to activate the killing plates to electrocute a rodent, is maintained even when the battery voltage has dropped to a level insufficient to fully activate the MOSFET.
10. The battery-operated electronic rodent trap as set forth in claim 9 , wherein outputs of each of a plurality of stages of the multi-state charge pump are connected in series to an input of a drive circuit for generating the voltage input to the gate of the MOSFET.
11. An electronic rodent trap, comprising:
a battery;
a micro-controller powered by the battery;
a voltage regulator arranged between the battery and the micro-controller;
a multi-stage charge pump having an input connected to the battery, including:
a plurality of diodes arranged in series, a first diode of the plurality of diodes having an input connected to the battery; and
a plurality of capacitors arranged in parallel, each capacitor of the plurality of capacitors being connected on a first end to a respective input/output terminal of the microcontroller and connected on a second end between an output of one of the plurality of diodes and an input of another one of the plurality of diodes, the charge pump driven by a pulse train from the micro-controller for generating an output having a voltage higher than the battery output voltage;
a drive circuit having an input connected to an output of a last one of the plurality of diodes of the charge pump;
a high voltage field-effect transistor connected between an output of the drive circuit and a transformer; and
killing plates coupled to the transformer for electrocuting a rodent when activated, the transistor rapidly switching a ground return path of the transformer to create a flyback voltage for activating the killing plates.
12. The electronic rodent trap of claim 11 , wherein an output voltage of the multi-stage charge pump is approximately equal to:
(battery voltage)+( n *micro-controller voltage)
wherein n is the number of stages of the multi-stage charge pump, and the micro-controller voltage is the voltage supplied to the micro-controller by the voltage regulator.