A Magnetic Proximity Switch Sensor Circuit is a cool gadget that can sense magnetic fields.
You can see this kind of sensor in lots of places, like in factories, security systems and automation.
The key component of this circuit is a magnetic reed switch which serves as the proximity sensor.
In this design an 555 timer chip and a CD4013 flip-flop chip work together to switch a relay on or off when a magnet comes near.
This action then controls an external device turning it on or off.
To make sure the circuit works well, it is important to use a steady 12 volt power supply.
Circuit Working:
Parts List:
| Component Type | Value/Part Number | Quantity |
|---|---|---|
| Resistors 1/4 Watt | 1k | 1 |
| 470k | 1 | |
| 10k | 1 | |
| 2.2k | 1 | |
| Capacitor | 1 | |
| Ceramic | 0.01µF, 2.2µF | 1 each |
| IC | 555 | 1 |
| IC | CD4013 | 1 |
| Transistor | BC547 | 1 |
| LED | 5mm 20mA any color | 1 |
| Diode | 1N4007 | 1 |
| Relay | 12V SPDT | 1 |
| Magnetic Switch | Reed Switch | 1 |
In the above circuit diagram when a magnet comes near S1 it causes the switch to close, which activates the circuit.
The IC1 555 is set up as a monostable multivibrator generating a pulse when S1 is triggered.
IC2 The CD4013 D flip-flop changes its state each time it receives a pulse from the IC1 555 timer.
The BC547 transistor Q1 functions like a switch that manages the 12V SPDT relay.
The LED1 light shows that the circuit has found the magnetic field and is working to activate the relay part.
After the monostable pulse finishes the IC1 555 timers output drops which turns the LED off.
D1 1N4007 safeguards the circuit by preventing voltage spikes from the relay coil that could cause damage.
Formulas with Calculations:
Below are the formulas with calculations for Magnetic Proximity Switch Sensor Circuit
IC1 555 Monostable Pulse Duration:
Formula: T = 1.1 * R2 * C2
where,
R2 = 470k and C2 = 2.2µF
The calculation shows:
T = 1.1 * 470000 * 2.2 * 10^(-6)
T = 1.14 seconds
This means the IC1 555 timer output stays HIGH for approximately 1.14 seconds each time the magnetic switch is triggered.
Base Current of Transistor Q1 BC547:
Formula: Ib = (Vin – VBE) / R4
where:
Vin = 12V, VBE = 0.7V, R4 = 2.2k
The calculation shows
Ib = (12 – 0.7) / 2200
Ib = 5.2 mA
The BC547 transistor has a current gain (hFE) of around 200, which means the collector current will be sufficient to drive the relay.
How to Build:
To build a Magnetic Proximity Switch Sensor Circuit following steps are needed to be followed for designing your own circuit:
- Assemble all the components as mentioned in the above circuit diagram
- Connect pin 1 of IC1 555 to GND of the circuit
- Connect pin 2 of IC1 between resistor R3 and S1 switch
- Connect pin 3 of IC1 to pin 3 of IC2
- Connect pin 4 and pin 8 of IC1 to +12V DC
- Connect pin 5 to GND through capacitor C1
- Connect pin 6 of IC1 to pin 7 of IC1
- Connect the positive of capacitor C2 between pin 6 and GND
- Connect resistor R2 between pin 7 of IC1 and positive supply
- Connect one terminal of resistor R1 between pin 3 of IC1 and pin 3 IC2 and other terminal of R1 resistor connect to anode of LED1 and cathode of LED1 connect to GND
- Connect pin 1 of IC2 CD4013 to base of transistor Q1 through resistor R4
- Connect pin 4,6,7,8,9,10, and 11 of IC2 to GND of the circuit
- Connect pin 2 of IC2 to pin 5 of IC2
- Connect pin 14 of IC2 to positive supply of +12V DC
- Connect collector of transistor Q1 to positive supply of +12V DC through diode D1
- Connect the emitter of transistor Q1 to GND
- Connect the COIL pins of 12V relay to collector of Q1 transistor and other to positive supply of 12V
Conclusion:
The Magnetic Proximity Switch Sensor Circuit is an easy and efficient method for sensing magnetic fields and controlling external devices with a relay.
It is useful in areas like security systems, industrial automation and smart control setups.
By using an 555 timer and a CD4013 flip-flop the circuit operates reliably and the relay output makes it simple to connect with different electrical equipment.