How To Make A Resistor Based Voltage Divider
Using AI As A Helper

What’s In This Page?

How to use AI to calculate the resistor values to make a resistor based voltage divider that suits your needs. A prompt that you can use to calculate the values and video demo are included.

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About Using A Resistor Based Voltage Divider

• These voltage dividers are not suitable for powering devices that draw significant current because the voltage will drop under load.

• For powering logic circuits or microcontrollers, use a voltage regulator (like LM7805, buck converter, or LDO) instead.

Resistor Based Voltage Dividers And AI

The image to the left is a circuit diagram for a voltage divider.

The equation for calculating the resistor values needed to get the V out that you want is straightforward.

It is R2 = R1*(Vin-Vout)/Vout

Rather than doing it by hand, use AI to do the work for you.

Here is a prompt that you can use to have AI do the work for you.

What is the R2 resistor value for a voltage divider circuit for 12V input, 5V output, and R1 is 1000 ohms.

Just change the values in the prompt to suit your requirements.

I used ChatGpt and received the following response for the prompt that I have shown above.

Answer

To determine the value of the resistor \( R_2 \) in a voltage divider circuit with an input voltage \( V_i = 12V \), an output voltage \( V_o = 5V \), and a resistor \( R_1 = 1000 \Omega \), we use the voltage divider formula:

\[ V_o = V_i \left(\frac{R_2}{R_1 + R_2}\right) \]

Rearranging for \( R_2 \):

\[ 5V = 12V \left(\frac{R_2}{1000 \Omega + R_2}\right) \]

\[ \frac{5}{12} = \frac{R_2}{1000 \Omega + R_2} \]

\[ 5(1000 \Omega + R_2) = 12R_2 \]

\[ 5000 \Omega + 5R_2 = 12R_2 \]

\[ 5000 \Omega = 7R_2 \]

\[ R_2 = \frac{5000 \Omega}{7} \]

\[ R_2 \approx 714.29 \Omega \]

So, the value of \( R_2 \) is approximately 714.29 ohms.

Applying This Information

The result is APPOXIMATELY 714.29 ohms.

Since at the time of writing this page, I had 1 k and 680 ohm resistors in my stash, I put them on a breadboard and tested the result.  The result was 4.9 volts.

That’s good enough to power an Arduino Nano or Mini pro, an HC-05 and an L239D motor controller.

Practically speaking, anything between 680 and 750 ohms will give you a workable voltage.

If you use prompt values to suit your needs, test with resistor values near what ChatGPT recommends.

Video Demonstration

Video In Editing

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