Doorbell Light

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The doorbell light is a combination "smart" doorbell actuator and home entry light. It features a microcontroller-based touchless doorbell chime actuator that is triggered by breaking a modulated beam of Infrared energy with the touch of a finger. The microcontroller detects the change in energy and triggers a solid state MOSFET to activate the doorbell chime for a predefined period of time. During the time the chime is activated, the only power to the micro is stored up in a capacitor which continues to operate the circuits long enough for the chime to complete its cycle. Once the chime is de-activated, power is restored to the power supply.

The power to the doorbell light is 16-24 volts AC that is rectified and filtered and finally converted to 5 VDC using a switching regulator that also has the distinct feature of boosting the secondary current as it drops the voltage. The primary current is limited to 70 mA to avoid activating the chime. But the secondary current is over 200 mA. This provides more than enough current to operate the microcontroller and the high energy light emitting diode (LED) which draws over 150 mA and provides enough light to illuminate the porch. The circuitry detects daylight and provides dusk to dawn illumination for about one penny per week. The LED is also used to provide feed back for doorbell activation by flashing before and after the doorbell is activated.

The doorbell light is about the same size as a conventional doorbell button and replaces a conventional button intended to operate an electro mechanical chime. The energy management features of the doorbell light are protected by three US patents.

Additional features such as a video camera, RF devices, etc. can be added if packaging space and energy constraints allow.



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  • Name:
    Peter Langer
  • Type of entry:
  • Profession:
  • Peter's hobbies and activities:
    Visual Basic,motorcycles, RC boats and planes, Grandchildren, product development
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  • Peter is inspired by:
    Energy conservation, design efficiency, novelty, creativity
  • Software used for this entry:
    PIC Basic Profesional, eMachineshop CAD software, Eagle schematic capture
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