The author wanted a very cheap and simple alarm for some of his possessions, such as his electrically assisted bicycle.
Creating an Affordable Bicycle Alarm System
This alarm system utilizes an inexpensive window alarm, enhanced with a 1-minute time-out function. The 555 timer’s output pulse replaces the reed switch in the window alarm. A sensor near the bicycle’s front wheel, coupled with a magnet mounted on the spokes, triggers the 555 timer. Both components are sourced from an economical bicycle computer.
Efficient Circuit Design and Power Source
The bicycle’s front wheel remains unlocked, allowing the reed switch to briefly close as the wheel turns. This action triggers the 555 timer, activating the window alarm. The circuit’s power consumption is minimal and can be sustained by the window alarm’s batteries. There is ample space within the window alarm’s enclosure to accommodate the added time switch.
Compact and Discreet Security Solution
The result is a cost-effective, compact device requiring only a single cable connected to the reed switch on the front wheel. The noise it generates is remarkably loud. After approximately one minute, the alarm ceases, returning to standby mode. Mounting options include inconspicuous locations such as under the saddle, inside a large front light, or within the battery compartment.
Enhancing Security and Raising Public Awareness
Ideally, the alarm serves as a deterrent, scaring away potential thieves, or at the very least, alerting passersby to suspicious activity.
Understanding Bradycardia: Slow Heart Rate in Adults
In the medical context, a pulse signifies the tactile detection of the cardiac cycle through artery compression. Palpation points include the neck, wrist, groin, behind the knee, near the ankle joint, and foot.
Bradycardia: Definition and Considerations
Bradycardia refers to a heart rate that is excessively slow, the definition of which can vary based on age and physical health. For adults, a resting heart rate below 60 beats per minute (BPM) qualifies as bradycardia. Elderly individuals are particularly susceptible to this condition.