This simple circuit made for controlling the speed of low voltage DC motors uses the TDA7274.
This design allows for precise speed adjustments in a way that is easy to understand and very efficient.
The IC TDA7274 is a special motor driver chip that is designed to manage the speed of DC motors in situations where low voltage and low power are needed.
It has a built in voltage reference and can work with input voltages from 1.8 to 6 volts.
It also provides a strong output current of up to 700 milliamperes and stays stable even with temperature changes, making it great for many low power DC motor speed control tasks.
The Vs power supply voltage should be selected based on the motors requirements and can range from 1.8 volts to 6 volts.
The maximum output current for this circuit is limited to 700 milliamperes.
Circuit Working:
Parts List:
| Component | Specification | Quantity |
|---|---|---|
| Resistors | 220Ω, 2k 1/4 watt | 1 each |
| Potentiometer | 10k | 1 |
| Capacitors | Electrolytic 4.7µF 25V | 1 |
| Electrolytic 1µF 25V | 1 | |
| Semiconductors | IC TDA7274 | 1 |
| DC Motor | – | 1 |
The circuit mainly relies on the TDA7274 chip which is the key component that controls how fast the motor runs based on the voltage applied to its input pins.
The resistors R1, R2 and VR1 are really important because they help adjust the control voltage allowing for accurate speed control of the motor.
The TDA7274 IC1 acts as the main controller that manages the power going to the motor.
The resistors R1, R2 and VR1 work together to form a voltage divider that changes the control signal.
Also, there are capacitors C1 and C2 included to reduce noise and keep everything running smoothly.
The motor is set up in a way that ensures it gets the right voltage, which helps it operate at different speeds.
Formulas with Calculations:
Below mentioned are the formulas with calculations for Simple TDA7274 Based Low Voltage Motor Speed Controller Circuit:
Voltage Divider Formula:
Vcontrol = Vs * (VR1 / (R2 + VR1))
where,
- Vcontrol is the voltage applied to the control pin
- Vs is the supply voltage
- R2 and VR1 form the voltage divider
Example Calculation:
If assume Vs = 6V, R2 = 2k and VR1 = 10k
Vcontrol = 6 * (10k / (2k + 10k))
Vcontrol = 6 * (10 / 12)
Vcontrol = 5V
So, with a 6V power supply the control voltage would be 5V which regulates the motor speed accordingly.
If required by varying VR1 the control voltage changes, which adjusts the motor speed accordingly.
How to Build:
Below are the steps for connection of circuit to build a Simple TDA7274 Based Low Voltage Motor Speed Controller Circuit:
- Gather all the components mentioned in the above circuit diagram
- Connect pin 3 of IC1 to positive supply of the circuit.
- Connect pin 4 of IC1 to one end of VR1 pot.
- Connect pin 5 of IC1 to GND.
- Connect pin 6 of IC1 between resistors R1 and R2.
- Connect pin 8 of IC1 between resistor R2 and VR1 pot.
- Connect positive of capacitor C1 to positive supply terminal and negative of capacitor to pin 6 of IC1
- Connect DC motor one end to positive supply terminal and other end to pin 4 of IC1.
- Connect positive of capacitor C2 to positive supply terminal and negative to pin 4 of IC1.
Conclusion:
This Simple TDA7274 Based Low Voltage Motor Speed Controller Circuit for controlling the speed of a low voltage DC motor is both easy to use and effective.
It uses the TDA7274 IC to help manage the motors speed.
You can change the speed by simply adjusting a set of resistors, which makes it easy and avoids complicated parts.
This design is perfect for small motor projects providing a steady and adjustable speed.
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