This project will be published in a few weeks. If you want to access it now, refer to Electronics For You’s January 2023 Issue–print or ezine edition.
The World Health Organization (WHO) recommends that everyone should rub their hands with soap for at least 20 seconds before washing with water to prevent transmission of the novel Corona virus, which is again on rise, in addition to social distancing. The 20-second period can be checked with wristwatches and the stopwatches on mobile phones, but these are not convenient to use while washing hands. This proposed circuit rings a buzzer for 20 seconds and switches on an LED for audio as well as visual indication (for those with hearing issues).
The author’s prototype is shown in Fig. 1.
