You can use resistors to divide voltage.
A circuit with just some resistors may not seem very interesting but you can learn something. If you put two resistors in-line with each other, then the total resistance will be the sum of each resistor. This type of arrangement is called in series. You can learn more by listening to the previous episode about series vs. parallel.
While you can think of multiple resistors in series as being equivalent to a single larger resistor they have an interesting property that will divide the voltage. Since they’re in series, there’s only one path for current to flow so that means that the current will be the same through each resistor. The total resistance will determine this current. And each resistor will share a portion of the voltage. If you have two resistors and they’re both the same value, then each will share half the voltage. But if one resistor is larger, then it will carry more of the voltage.
You can use this in designs where you want to adjust maybe the volume or brightness or speed of something. You can use a variable resistor called a potentiometer or pot for short. Most knobs that have a minimum and maximum amount they can be turned are actually variable resistors. Now if you have a newer device that has knobs that can turn as much as you want, then these are not potentiometers.
Listen to the episode or you can also read the full transcript below.
Transcript
Make sure to listen to recent earlier episodes especially about voltage, current, and resistance. This episode builds on that.
Let’s start with something basic. You should never connect a 5 volt supply voltage directly to ground. Or whatever voltage level you’re working with. This is called a short. Because you provided a shortcut path for all the current to flow through instead of the rest of your circuit. Sometimes you might want to short out a portion of your circuit but never the whole thing. Not only will your circuit stop working, but you could damage the power supply, blow out fuses, and many other undesirable effects.
Current will always take the path of least resistance. And a short has almost no resistance. The power supply will try to maintain its voltage level and that means it’ll have to push a lot of current through a short circuit. It may not be able to keep up. You can damage batteries and start fires. Always make sure that there’s a proper amount of resistance between your positive and negative power supply terminals. Or between 5 volts and ground in many cases.
A circuit with just some resistors may not seem very interesting but you can learn something. If you put two resistors in-line with each other, then the total resistance will be the sum of each resistor. This type of arrangement is called in series. You can learn more by listening to the previous episode about series vs. parallel.
While you can think of multiple resistors in series as being equivalent to a single larger resistor they have an interesting property that will divide the voltage. Since they’re in series, there’s only one path for current to flow so that means that the current will be the same through each resistor. The total resistance will determine this current. And each resistor will share a portion of the voltage. If you have two resistors and they’re both the same value, then each will share half the voltage. But if one resistor is larger, then it will carry more of the voltage.
You can use this in designs where you want to adjust maybe the volume or brightness or speed of something. You can use a variable resistor called a potentiometer or pot for short. Most knobs that have a minimum and maximum amount they can be turned are actually variable resistors. Now if you have a newer device that has knobs that can turn as much as you want, then these are not potentiometers.
A potentiometer is really just a fixed resistor that has a sliding terminal that can be moved up and down the resistor. This divides the resistor into two parts where one part starts out at zero ohms and slowly increases as you turn the knob and that causes the other part to decrease.
Sometimes, there can be a switch included inside the potentiometer. You’ve probably operated radios where there’s a small rotating wheel on one side. You move the wheel and it clicks to turn on the radio and then as you keep moving the wheel it gets louder. All of this is possible because of voltage dividers.