Build a 4017 Live-Line Detector Circuit – Simple & Inspiring
Identifies the existence of a live electrical supply
Minimal component count
Circuit diagram
Components:
- C1 100nF 63V Polypropylene or Ceramic Capacitor
- D1 Red LED (any variety)
- IC1 4017 Decade counter possessing 10 outputs that are decoded
- P1 SPST Pushbutton
- B1 3V Battery (two 1.5V AA or AAA cells connected in series, for example)
- Sensing probe__ranging from 3 to 15 cm, a rigid, insulated wire piece
Circuit Functionality:
When the device is brought near a energized electrical line (protected, and even concealed within plaster), capacitive interaction between the electrical line and the probe triggers the counter, and results in the LED flashing five times per second, as the 4017 IC divides the 50Hz mains frequency by 10.When distant from the electrical supply, the device ceases counting, and the LED remains permanently extinguished.
Precautions:
- Adjustable sensitivity can be achieved using a longer or shorter sensing probe.
- Because of the 3V operation, the LED’s current-limiting resistor is not required
More about components
The 4017 IC is a versatile decade counter integrated circuit. It's a digital integrated circuit that can count from 0 to 9, and can be configured to count up or down. This particular IC has ten decoded outputs, which means each output represents a different count value. Its typical applications include digital counters, frequency dividers, and timing circuits. The IC operates on a 5V supply, although this circuit uses a 3V power source, which requires proper voltage level conversion for optimal function. Its internal circuitry includes a counter, shift registers, and logic gates for implementing the counting and decoding functions. It is a commonly used component in hobby electronics projects and embedded systems due to its relatively simple design and readily available documentation.
circuit from http://www.redcircuits.com/