MOSFET Gate Voltage Boosting in Electronic Rodent Traps

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Solution Overview

Problem

Existing electronic rodent traps face a challenge in maintaining a consistently high voltage required for effective rodent dispatch as battery voltage drops, leading to reduced efficacy over the life of the batteries.

Innovation Solution

A multi-stage charge pump circuit driven by a micro-controller generates a pulse train to boost the voltage input to the MOSFET switch, ensuring the MOSFET remains fully activated and the flyback voltage is maintained even at low battery levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the battery voltage is used directly to drive the MOSFET gate, then the circuit is simple, but the MOSFET cannot be fully turned on when battery voltage drops, significantly reducing the flyback voltage

Engineering Contradiction:
Improvecircuit complexityVSAvoidtrap effectiveness
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

A charge pump circuit is introduced as an intermediary between the battery and the MOSFET gate. This charge pump boosts the battery voltage to a higher level (e.g., 10V or 12V) to ensure the MOSFET gate receives sufficient voltage for full activation, even when the battery voltage has dropped. The charge pump acts as a mediator that decouples the MOSFET gate voltage from the direct battery voltage, maintaining reliable trap effectiveness throughout the battery's life cycle.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a voltage booster circuit is added to maintain high gate voltage, then the MOSFET remains fully activated, but the device complexity increases

Engineering Contradiction:
ImproveMOSFET activation reliabilityVSAvoidcircuit complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The charge pump circuit dynamically changes the voltage parameter delivered to the MOSFET gate. Instead of using the raw battery voltage which decreases over time, the charge pump actively regulates and boosts the voltage to maintain a constant high level (e.g., 10V-12V) throughout operation. This parameter change ensures the MOSFET remains in full activation mode, compensating for battery voltage degradation without requiring complex external voltage regulation components.

Inventive Principle:
Principle #35Parameter changes

3Duration of action of moving object

If the battery voltage drops, then the operational life of the battery extends, but the trap effectiveness significantly reduces

Engineering Contradiction:
Improvebattery lifeVSAvoidtrap effectiveness
Core Design Contradiction:
Duration of action of moving objectVSReliability

Solution Approach 1:

The charge pump circuit incorporates feedback mechanisms to monitor the battery voltage level and adjust its boosting operation accordingly. As the battery voltage drops over time, the charge pump detects this change and increases its voltage multiplication ratio to maintain the MOSFET gate voltage above the threshold for full activation. This feedback control allows the trap to maintain effectiveness throughout the entire battery life cycle, from fresh to depleted batteries.

Inventive Principle:
Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution extends the operational effectiveness of electronic rodent traps by maintaining a high output voltage for a longer duration, enhancing the trap's ability to kill rodents and increasing cost-effectiveness.

Implementation Method 1

The circuit includes a multi-stage charge pump driven by a pulse train that is generated by a micro-controller. 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 is low.

Methodology Applied
Scientific EffectCharge pump:

Implementation Method 2

The power N-channel MOSFET switch generates a high voltage by rapidly switching the ground return path for a transformer on and off. The switching action creates a flyback voltage from the transformer on the order of thousands of volts, which is capable of killing a rodent.

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3731633B1Electronic rodent trap with voltage booster circuit for improved trap performance over the life of the battery
Publication Date: 2024.10.30 WOODSTREAM CORP
  • EP3731633B1 patent drawingFigure 1~2
  • EP3731633B1 patent drawing

AI summary

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.