SUMMARY
The key fob operates correctly with a CR2032 battery but fails to function when powered by an external power supply, even when the voltage is confirmed at 6V. The issue arises due to the power supply's inability to provide sufficient current peaks required for transmission, particularly at the high frequency of 432MHz. Adding a capacitor, specifically a 100µF tantalum or ceramic capacitor, to the battery terminals is recommended to buffer the power supply and support the necessary current demands. Users have confirmed that the battery acts as an essential component for the fob's antenna resonance, which is disrupted when using a power supply.
PREREQUISITES
- Understanding of RF transmission principles, particularly at 432MHz
- Familiarity with key fob circuitry and operation
- Knowledge of power supply characteristics and limitations
- Experience with measuring current and voltage using a multimeter
NEXT STEPS
- Research the effects of inductance on high-frequency circuits
- Learn about the role of capacitors in power supply buffering
- Investigate the design and function of RF antennas in key fobs
- Explore the differences between battery and power supply characteristics in electronic devices
USEFUL FOR
Electronics engineers, hobbyists working with RF devices, and anyone troubleshooting key fob power issues will benefit from this discussion.