Call bells, designed to draw attention, are commonly used in various environments such as offices, hospitals and residential care homes. Here, we explore a simple 12V LED dimmer circuit, incorporating an LM556 dual timer IC, which also functions as a call bell. The LM556 dual timer IC houses two 555 timers within a single 14-pin package. In this LM556 PWM-based LED dimmer circuit, the brightness of the LEDs is effortlessly controlled using a potentiometer. The author’s prototype is shown in Fig. 1.
Circuit and working
The circuit diagram of the LED strip dimmer and call bell, as shown in Fig. 2, is built around a 230V AC primary to 15V, 500mA secondary transformer (X1), a bridge rectifier (BR1), a 12V voltage regulator (LM7812, IC1), a dual timer (LM556, IC2), a MOSFET (IRFZ44, T1), a transistor (BC337, T2), an 8-ohm 0.5-watt speaker (LS1), and a few other components.
The 230V AC mains voltage is stepped down to 15V through stepdown transformer X1. This 15V secondary output of X1 is fed to bridge rectifier BR1. Capacitor C1 filters the voltage ripples, and the filtered output is supplied to the voltage regulator LM7812 (IC1). IC1 provides a 12V regulated DC output to power IC2. LED1 serves as a power-on indicator. Both timers of the dual timer LM556 (IC2A and IC2B) are configured in an astable multivibrator mode.
LED strip dimmer
この記事は Electronics For You の September 2024 版に掲載されています。
7 日間の Magzter GOLD 無料トライアルを開始して、何千もの厳選されたプレミアム ストーリー、9,000 以上の雑誌や新聞にアクセスしてください。
すでに購読者です ? サインイン
この記事は Electronics For You の September 2024 版に掲載されています。
7 日間の Magzter GOLD 無料トライアルを開始して、何千もの厳選されたプレミアム ストーリー、9,000 以上の雑誌や新聞にアクセスしてください。
すでに購読者です? サインイン
STK435 IC-Based STEREO AMPLIFIER
This stereo AF amplifier uses the STK435 IC, a highly popular choice due to its simplicity.
A SEWER DRAIN SHIELD For Smart Cities
Drainage systems are vital for storm water management but often transport pollutants, especially plastics, to rivers and oceans, harming ecosystems.
ESP32 SPEECH FUNCTION: Text To Speech
Speech capability in technology primarily has two dimensions: text to speech (TTS) and speech to text (STT). This device focuses on TTS.
World's Smallest Programable INDUSPHONE DESIGN
This is the second part of designing the world’s smallest phone, where the UI is integrated with the basic functions of the phone.
FLAME-SENSING FIRE ALARM Using An Arduino Nano
Fire safety alarms are crucial in both residential and industrial environments.
loT-Based Distribution Transformer CONDITION MONITORING SYSTEM
The proposed IoT-based distribution transformer condition monitoring system enables real-time monitoring of distribution transformers, identifying such deviations as overload conditions and overheating.
Wi-Fi 6 AND Wi-Fi 7 Powering The Next Wave of Smart Connectivity
Wi-Fi 6 leads with faster data rates and reduced latency while upcoming Wi-Fi 7's backward compatibility will facilitate gradual upgrades from Wi-Fi 6, easing transitions. However, advanced features like multi-link operation (MLO) and ultra-low latency may command a premium, making Wi-Fi 7 suited for high-end applications.
CHARGE FORWARD: High-Voltage Batteries And MSMEs Can Fuel INDIA'S EV REVOLUTION
A nuanced explanation of low- and high-voltage EV batteries by Dr Gokhale, Vice President for Battery Technology at JSW Energy, illuminates their advancements and influence. The essential role of MSMEs and academia in developing a strong EV ecosystem emerges, marking their significance for India's push towards self-reliance in this innovative field.
"MILES TO GO Before I Sleep"
A teacher illuminates the path to success through the light of knowledge, yet some teachers extend that light to society through their contributions and research. Known as the architect of the modern M3 electronic voting machine (EVM) and the voter verifiable paper audit trail (VVPAT) that transformed India's democratic process, Prof. (Dr) Rajat Moona's journey began in the modest town of Bareilly. Here is his story, as recounted to and written by EFY's Yashasvini Razdan.
STARTUPS & INNOVATORS
1 One Charger To Charge All Your Devices | 2 Harnessing AI Technology For Efficient Pest Management | 3 Wireless Light-Based Communication With Velmenni's Technology