The motor plays an important role in many engineering applications. People always search for an efficient and easy way to control these motors. There are many techniques available in both AC and DC to control DC motors Pulse width modulation is often used. Another interesting control is through voice.
In this project, the voice signals through a microphone are used to activate a dc motor. The heart of the circuit is a CA3140 IC that is working in comparator mode in the circuit.
Hardware Components
The following components are required to make Sound Controlled DC Motor Circuit
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Battery | 5V to 15V | 1 |
| 2. | NPN transistor | 2N3904 | 1 |
| 3. | Opamp IC | CA3140 | 1 |
| 5. | PNP transistor | BD140 | 1 |
| 6. | DC motor | – | 1 |
| 7. | Electret Mic | – | 1 |
| 8. | Resistors | 39K, 10K, 1K | 1, 2, 2 |
| 9. | Variable resistor | 10K | 1 |
CA3140 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of CA3140
Sound-Controlled DC Motor Circuit
Working Explanation
This simple circuit uses opamp CA3140 IC which is working in comparator mode in this circuit. The 10K variable resistor is used to adjust the sensitivity of the circuit. Whenever there is a voice signal available on the microphone, the comparator CA3140 generates a signal. Two transistors 2N3904 and BD140 are connected with pin6 of the IC to amplify these output signals. As a result of this generated signal, a DC-connected motor turns on. A lead can also be connected with the emitter of the NPN transistor to indicate the current output status. This circuit can be operated with a wide range of DC supplies i.e. from 5V to 15V.
Applications and uses:
Controlling the dc motor by turning it ON and OFF through sound has many applications. It can be used to control certain home appliances which could be great for blind people as they don’t need to find the switch to control the motor. It can be used in kid’s toys like cars, trucks, etc. It also has an application in robotics
