How To Reduce Voltage Using a Resistor? Step By Step

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Some of the devices connected to an electrical circuit can’t tolerate the direct voltage coming from the circuit’s power supply. As a result, the voltage has to be reduced to work properly and avoid getting damaged by the high voltage. One of the most common ways to reduce voltage is by using resistors.

How To Reduce Voltage Using a Resistor? 

To reduce voltage using a resistor, you need to use a voltage divider known as a potential divider; it is a passive linear circuit that generates an output voltage equal to the fraction of the input voltage. The division process results from distributing the input voltage between the components of the divide; these components are usually resistors.

  1. Connect the two resistors in series, where the second lead of the first resistor is connected to the first lead of the resistor.
  2. Then, connect the first lead of the first resistor to the positive terminal of the power supply, and connect the second lead of the second resistor to the negative terminal of the power supply.
  3. After connecting the two resistors, connect between the two resistors a jumper wire.

For example, a voltage divider can connect two resistors in series. The input voltage is supplied across the two resistors, and the output voltage comes from the connection point between the two resistors. Voltage dividers are used to reduce the voltage’s magnitude or produce a reference voltage, and they also can be used at low frequencies as attenuators for signals.

The voltage divider is more accurate when it consists only of resistors, where over a wide range, the frequency is required. In addition, the voltage divider can consist of capacitive elements to compensate for the load capacitance.

How To Reduce Voltage to Half its Value?

To reduce a voltage to half its value, you need to construct a voltage divider circuit consisting of 2 resistors; the two resistors should have the same value, such as a pair of 10KΩ. Then, connect the two resistors in series.

Then, connecting between the two resistors a jumper wire, the output voltage will be half the value of the input voltage; for example, if the input voltage was 5 volts, the output voltage would be 2.5 volts.

How to Calculate the Output Voltage? 

To calculate the output voltage in a divider circuit that consists of two resistors, you will need to use the following equation VR2 = Vin * R1 / R1 + R2; you reformat the equation to also calculate the value of the second resistor R2= (V)(R1)/(VIN – V).

When you want to reduce the voltage to any value you want, you need to calculate the value of the second resistor, R2; this way, you can determine which resistance value you need to reduce the voltage to the amount required.

For example, suppose you want to reduce the voltage of a circuit from 5 volts to 3 volts. In that case, If the resistor you are using in the circuit is 10KΩ, you need to calculate the value of the second resistor, which reduces the voltage to 3 volts.

Use the following equation to calculate the R2 value R2= (V)(R1)/(VIN – V). So, (3V)(10KΩ)/(5V – 3V)= 15KΩ; this means we need to connect a 15KΩ resistor in series with the first resistor and create a jumper wire between them.

How To Reduce Voltage From 12v to 5v Using a Resistor?

To reduce the voltage of a circuit from 12 volts to 5 volts, you need to construct a voltage divider circuit that consists of a 330 ohms resistor and 5 volts LED resistor diode; there is an internal resistance inside the diode, which is about 1 volt; therefore, the power delivered by the resistor to the diode is then reduced by this electricity.

However, this method might need some calculations to be more accurate, so if the current passing through the circuit is 0.02 amperes, this means the power of the circuit is 2 watts, which means you need to use a 330 ohms resistor in addition to the LED diode.

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How To Convert a 12v DC to 6 Volt DC Using a Resistor?

You can convert a 12 volts DC to 6 volts by using a voltage divider circuit that consists of a pair of 10KΩ resistors. Connect the two resistors in series, where the second lead of the first resistor is connected to the first lead of the resistor, and then connect the first lead of the first resistor to the positive terminal of the power supply

Then connect the second lead of the second resistor to the negative terminal of the power supply; after connecting the two resistors, connect between the two resistors and connect a jumper wire.

Can You Reduce Voltage From 24v to 5 using a Resistor?

Yes, you can reduce a voltage from 24 volts to 5 volts using resistors; you can do this by connecting 190 ohms and 50 ohms resistors to the circuit as a voltage divider, the first resistor (190) should be 2 watts at least, and the second resistor should be 0.6 watts at least.

Connect the two resistors in series, where the second lead of the first resistor is connected to the first lead of the resistor, and then connect the first lead of the first resistor to the positive terminal of the power supply

Then connect the second lead of the second resistor to the negative terminal of the power supply; after connecting the two resistors, connect between the two resistors a jumper wire.

Can You Reduce Voltage From 12v to 3v Using a Resistor?

Yes, you can reduce a voltage from 12 volts to 3volts using resistors. To know the ratio between the two resistors you should connect to the circuit to reduce the voltage, you should use the following equation V1*R2/(R1+R2) = V2. After solving this equation using V1= 12 and V2 = 3.

You will get the ratio between the two resistors, R2= R1/3; this means that one of the resistors connected to the circuit resistance should be three times the value of the other resistor. So, for example, if you are using a 5-ohm resistor, you will need to use another resistor of 15 ohms to reduce the voltage.

However, it’s not recommended because the resistors method is not effective. When the resistor drops a huge amount of voltage, it produces a significant amount of heat.

The heat affects the resistor and surrounding components’ efficiency. To reduce this amount of voltage, you should use voltage regulators as they are more effective and produce much less heat.

How Many Resistors are Required to Reduce The Voltage from 12V to 9V?

To know how many resistors are required, you need to calculate the resistance you need to add to reduce the voltage from 12 volts to 9 volts; you can calculate the resistance by dividing the voltage amount that will be reduced over the current passing through your circuit.

After calculating the resistance, you can now decide whether to use one resistor or more, and then you will connect the resistors used between the power supply and the load you are stepping down the voltage for. Again, you can do this small step by small step, for example:

  1. Connect a small resistor to the circuit first to reduce the voltage from 12 volts to 11 volts.
  2. Then, connect a larger resistor to the circuit to reduce the voltage by a large amount from 11 volts to 9 volts.

Conclusion

To sum up, to reduce a voltage using a resistor, you need to construct a voltage divider circuit, also known as a potential divider; it is a passive linear circuit that generates an output voltage equal to the fraction of the input voltage. The division process results from distributing the input voltage between the components of the divide; these components are usually resistors.

You can follow these steps to construct your voltage divider:

  1. Connect the two resistors in series, where the second lead of the first resistor is connected to the first lead of the resistor.
  2. Then, connect the first lead of the first resistor to the positive terminal of the power supply, and connect the second lead of the second resistor to the negative terminal of the power supply.
  3. After connecting the two resistors, connect between the two resistors a jumper wire.

The voltage divider is more accurate when it consists only of resistors, where over a wide range, the frequency is required. In addition, the voltage divider can consist of capacitive elements to compensate for the load capacitance.

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