Want to build a smart obstacle detector without using Arduino?
This simple project uses a 555 timer and an ultrasonic sensor to sense distance and control a DC motor automatically.
It is easy to make with low-cost and perfect for beginners in electronics.
This Obstacle Detection Circuit with 555 Timer and Ultrasonic Sensor is a cool DIY project, one should definitely give a try for.
Circuit Working:
Parts List:
| Component Type | Specification / Value | Quantity |
|---|---|---|
| Resistors (All resistors are 1/4 watt unless specified) | 1k | 1 |
| 100k | 1 | |
| 20k | 1 | |
| Capacitors | Electrolytic 10µF | 2 |
| Ceramic 1nF | 1 | |
| Semiconductors | IC 555 Timer | 1 |
| Transistor BC547 | 1 | |
| DC Motor | 1 | |
| HC-SR04 Ultrasonic Sensor | 1 |
The ultrasonic sensor HC-SR04 sends and receives ultrasonic waves.
The above circuit is in astable mode (continuous pulse generator).
It works as an oscillator.
The pulse frequency depends on resistors R1, R2 and capacitor C1.
These pulses keep triggering the ultrasonic sensor again and again.
Sensor keeps sending and receiving ultrasonic waves continuously.
When object comes near, echo signal activates transistor and motor turns ON.
When object goes away then there is no echo and motor stops.
Formula with Calculation:
555 timer gives pulse time by formula:
T = 1.1 × R1 × C1
Take the values:
R1 = 100kΩ = 100000Ω
C1 = 10µF = 0.00001F
T = 1.1 × 100000 × 0.00001
T = 1.1 sec
So output stays HIGH for about 1.1 seconds.
In this time transistor is ON and motor runs for short time.
How to Build:
To build a Obstacle Detection Circuit with 555 Timer and Ultrasonic Sensor follow the below steps:
- Take all parts same as circuit diagram.
- Connect HC-SR04 sensor VCC to +5V.
- GND pin to ground.
- Trig pin connect to pin 3 OUT of 555 timer.
- Echo pin goes through resistor R3 to transistor base.
- Connect 555 timer IC1 pins like this:
- Pin 1 GND to ground.
- Pin 2 TRIG connect to pin 6 THR.
- Pin 3 OUT connect to sensor Trig pin.
- Pin 4 RESET to +5V.
- Pin 5 CV connect to ground through capacitor C3.
- Pin 6 THR connect to pin 2 TRIG.
- Pin 7 DIS between resistors R1 and R2.
- Pin 8 VCC to +5V.
- Now connect transistor Q1.
- Base connect with resistor R3 and capacitor C2.
- Collector connect to +5V.
- Emitter connect to positive of DC motor.
- Motor negative goes to ground.
Conclusion:
This Obstacle Detection Circuit with 555 Timer and Ultrasonic Sensor works simple and easy.
No Arduino needed.
Ultrasonic sensor finds object and 555 timer gives short pulse.
Transistor turns motor ON.
When object goes away then motor stops.
It is good for small automation and learning projects.
References:
Second Opinions on an Ultrasonic Sensor Circuit Using 555 Timer