Starting a series of articles to explain the circuit design considerations and troubleshooting to cure defects. When we see a circuit, sometimes we think that how these components are selected? Why some additional components are included to make the circuit over designed? Why a specific value component is selected. All these are some of the common doubts arise when we see a circuit. Circuit design is an art which has many aims. First is its proper working and second is its compactness. In addition to this, we have to use rare components not easily seen in common circuits for the purpose of introducing their working to hobbyists. Another important thing to remember while selecting a component, especially ICs, transistors, sensors etc, is the ultimate result of the circuit to satisfy our needs.
A circuit can be designed in different ways according to the idea of the designer. Some designers design the circuit using only a few components with a concept that this is sufficient and it is easy to describe. The circuit will work but we cannot study anything from it. If the circuit is slightly complicated, the performance will be more accurate and a student can analyze the working of each section in the circuit. See, a hobbyist or a circuit designer is not designing the circuit for the purpose of commercial sale but to understand the basics of electronics. For commercial applications, the design is entirely different and the only aim is to satisfy the needs, low cost and low size. You can see the power supply in china make low cost LED light. They are using only a capacitor and a diode to convert AC to DC. So, design the circuit as per your idea, interest and purpose.
Do not try to follow others because each person has his own ideas and the way of designing. Do not under estimate other’s designs because it is their design according to their mind. But the ultimate aim should be proper working of the circuit. We can light an LED with a series resistor starting from 100 ohms to 1 kilo ohms with a 12 volt supply. Take your own value depending on the forward voltage of the LED. Only difference is change in brightness and current consumption. If you use a high value resistor, brightness will be reduced. So it is your choice according the requirement.
If a circuit is not working, don’t throw it away. Find out the error and make it working. There lies your skill and ability. Experimentation is always better than too much theory and calculations using paper and pen.
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