In this post we will find out about the contactless phase indicator circuit using IC 4017.
This handy tool can check wires and cables to see if they have electricity running through them, without even touching them.
It is great for electricians to find problems in complicated electrical systems.
The light will turn on if there is electricity in the wire.
Circuit Working:
Parts List:
| Component Type | Description | Quantity | Notes |
|---|---|---|---|
| Resistor | 220Ω | 1 | |
| Capacitors | Ceramic 0.1µF | 1 | |
| Electrolytic 100µF 25V | 1 | ||
| Semiconductors | IC 4017 | 1 | |
| LED | Green 5mm 20mA | 1 | |
| Fixed Inductor | 10uH | 1 | |
| Battery | 9V | 1 |
Capable of detecting AC in the power cord from a distance of one foot or more this circuit senses the AC frequency around the power cord which manifests as an AC hum and indicates this through the LED.
The IC CD 4017 is a Johnson decade counter with ten outputs.
Its clock input pin 14 is highly sensitive to electromotive force e.m.f causing the outputs of the IC to become high one by one as pulses are received at pin 14.
The IC only counts if the reset pin 15 is grounded.
In this circuit, only one output pin 11 is used to illuminate the LED.
The fixed inductor L1 receives e.m.f from the power cord and sends it as pulses to the input of the IC, rapidly making the outputs high and causing the LED to blink.
To use the circuit, place it near the power cord of the instrument.
No adjustments are necessary and the LED will illuminate to indicate power.
If the LED remains off it indicates that current is not flowing through the power cord.
Formulas:
The circuit above counts the pulses from a voltage divider circuit that is coupled to the mains voltage 220V using the CD 4017 decade counter chip.
The mains voltage is lowered by the voltage divider circuit to an IC safe level.
The CD 4017 receives pulses produced by the positive and negative voltage swings in the AC power.
The circuit can identify the phase of the AC voltage by counting the pulses.
Capacitance reactance:
The circuits reactance, introduced by capacitor C2, may have an impact on the pulse waveform that the CD 4017 observes.
One may compute a capacitors reactance with the following formula:
XC = 1 / (2 * π * f * C)
where,
- XC is the capacitive reactance in ohms.
- π is a mathematical constant roughly equal to 3.14
- f is the frequency of the AC voltage either 50Hz or 60Hz, and
- C is the capacitance in farads, or 0.1uF in the circuit.
A formula that connects the inductance L and capacitance C of an ideal LC circuit to its resonant frequency (f):
f = 1 / (2 * π * sqrt(L * C))
where,
- f is how many hertz Hz the resonance frequency.
- π is a mathematical constant that, is roughly equivalent to 3.14
- L is the inductance in henrys H (value of L1 in the circuit)
- C is the capacitance measured in farads F (the circuits C1 value).
Note:
The phase detector circuits fundamental functionality may not depend on the exact value of the inductor L1.
Its main purpose is to restrict inrush current and maybe serve as a filter circuit component.
More likely than not, the number selected for L1 would be determined by practical factors like size, cost, and current rating, not by a precise mathematical formula.
How to Build:
To build a Simple contactless 220V Phase Detector Circuit follow the below mentioned assembling steps:
Connect IC CD 4017:
- Place the IC CD 4017 on the breadboard or PCB.
- Connect pin 16 VDD to the positive terminal of the power source and pin 8 ground to the negative terminal.
Connect LED:
- Connect the longer leg anode of the LED to pin 11 of the IC via a current limiting resistor 220Ω, and connect the shorter leg cathode to the ground.
Connect Inductor L1:
- Connect one end of the fixed inductor L1 to the power cord of the instrument and the other end to the input pin 14 of the IC CD 4017.
- Connect pin 13 and pin 15 of the IC to the ground.
- Connect the power supply to the circuit.
- Make sure the voltage is appropriate for the components used.
- Place the circuit near the power cord of the instrument.
- If everything is connected correctly the LED should light up when there is AC flowing through the power cord.
- If the LED remains off, check the connections and component values.
Adjustments:
- If needed, adjust the circuit for optimal sensitivity and performance.
Note:
- Remember to exercise caution when working with AC mains voltage.
- If you are not experienced with electronics consider seeking assistance from someone who is.
Conclusion:
The contactless 220V Phase Detector Circuit using IC 4017 is a simple and efficient circuit that can detect the presence of AC voltage in wires or cables without direct contact.
This circuit is particularly useful for troubleshooting and identifying live wires in mains wiring systems providing a safe and effective method for detecting AC voltage.