How can I reduce the voltage drop

Series resistance at consumers

Many electrical components work with a specified electrical voltage. For example, the required voltage of light-emitting diodes (LEDs) is around 1.5 volts to 2.5 volts, depending on the design. However, it is often the case that the supply voltage is much higher, e.g. 12 volts. For example, if the consumers were to be connected directly to the higher supply voltage, they could either be destroyed or their functionality would be restricted. To prevent this from happening, a solution must be found to lower the supply voltage at the consumers.

A solution to lower the electrical voltage is a combination of consumer and resistor in series. Because, with a series connection, the electrical voltage is divided proportionally to the resistances. The behavior can be used to form a series circuit with the consumer, e.g. with a light-emitting diode and a resistor, and thus reduce the supply voltage to the desired value.

According to the calculation rules of the series connection, it does not matter whether the resistor is placed before or after the consumer. Nevertheless, the resistance in a constellation of consumer and upstream or downstream resistor connected in series is called a series resistor.

The task of the series resistor is basically to reduce the supply voltage to the necessary voltage and to limit the current. The electrical voltage is divided between the consumer and the series resistor proportionally to the resistors. Many electrical components already have integrated series resistors. However, these must be selected carefully as they are designed for a specific operating voltage.

A consumer can of course not only be combined with one series resistor, but with several. It would be conceivable, for example, to create a step regulator with several series resistors and several connections. Depending on the selected level, e.g. 1, 2 or 3 series resistors could be switched on in order to achieve different speeds of a consumer.

The energy is of course not lost in the series resistors. It is usually converted into thermal energy, which is why the series resistors often get warm during operation. This means that energy is consumed in the process without any benefit from it. This is why series resistors are usually used for small currents in the mA range. With larger currents, the energy losses would be enormous and that would not be economical. For this reason, transformers are often used to reduce the electrical voltage in the case of larger currents.

So that the consumer or the series resistors are protected in the event of overheating, a thermal fuse could also be installed to protect them. These melt when the heat is too high and interrupt the electrical circuit.