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If you’ve been working with Arduinos and other electronic devices for even a short while you probably have come up with a method of powering them up on your workbench. USB power bricks and bench power supplies will do the job very nicely.  With the Arduino you can simply power the device with a computers USB port.  Getting electricity was never so easy!

But after you’ve finished your design you’ll often want to build a more permanent version of your project, and for that you’ll need to consider how to go about providing power to it.

Electronic devices like Arduino’s require “logic level” voltages to function. These “logic level” voltages come in two flavors – the traditional 5 volts DC that is also known as “TTL level” voltage and the power-saving 3.3 volt DC supply that is used in many low-powered devices. In both cases the voltages need to be regulated fairly precisely to avoid damaging components.

A USB power brick can be a simple solution in many cases. It provides a regulated 5 volt DC supply that is suitable for most electronic devices and its fully enclosed design protects you from any chance of electric shock.

But what if you want to power your device using batteries? Getting an exact and consistent 5 or 3.3 volts from a battery is a challenge, especially as the battery discharges.

Today we will look at several low cost options for providing regulated power to your electronic designs.

Power For Your Electronics Projects

Common Voltage Requirements

There are several standard voltage levels that your design might require, some designs will need more than one of them. A few of them are as follows:

  • 3.3 Volts DC – This is a common voltage used in low-powered digital devices.
  • 5 Volts DC – This is the standard TTL (Transistor Transistor Logic) voltage used by digital devices.
  • 6 Volts DC – Often used for DC and servo motors.
  • 12 Volts DC – Also used with DC motors as well as many stepper motors.
  • 48 Volts DC – Used in professional audio gear as a “phantom supply” for microphones.

All of the above voltage levels are positive in reference to ground. Some older designs also required negative voltages, for example -12 Volts DC was used in the RS-232 serial connection that used to be standard on all computers and modems. Audio amplifiers often require both positive and negative supplies.

Voltage Regulation

Logic level voltages need to be very precisely regulated. For example for TTL logic to function correctly the supply voltage needs to be between 4.75 and 5.25 volts, any lower will cause the logic components to stop working correctly and any higher can literally destroy them.

Some supply voltage requirements are less stringent. Power supplied to motors, LEDS and other display and electromechanical components does not need to be regulated as as strictly as it does for logic supply voltages.  These power supplies are often not regulated to save cost in the final design.

Voltage regulation for line powered devices is not that difficult as the input voltage to the regulator circuitry is fairly constant. However battery powered designs provide a much greater challenge as battery voltage levels will fluctuate as the battery discharges.  

Devices that can be powered by both line voltages and batteries often have additional circuitry for charging the batteries when the device is being line powered. Depending upon the battery technology employed in the design this can range from a simple to very complex charging circuit.

Current Requirements

The power supply voltage level is not the only specification that must be taken into account when designing a power supply for your project.  Just as important is to determine the current requirements of the project.

Unlike voltage requirements the current that a project consumes is not always a static value.  Motors, LED and other displays, speakers and other transducers can cause the current draw to fluctuate and you need to design your power supply to accommodate the “worst case” situation where every motor, indicator and sounder is being operated at full capacity.

Once again current requirements can be a challenge in a battery powered design. As a battery discharges its current capabilities are diminished, trying to exceed these current capabilities can cause the battery to discharge rapidly.


Another important aspect of voltage regulator design is efficiency. The regulator or voltage convertor itself will consume some electricity that could otherwise have been used to power up your project.

Efficiency goes hand in hand with heat production, an inefficient regulator design will dissipate its excess energy as heat. Unless you’re deliberately trying to heat up your circuitry this is not a good thing!  Heat is one of the greatest enemies of electronic components and if your regulator gives off a lot of heat you’ll need to workout ventilation and perhaps heat sinking into your design.

No design is 100% efficient so some heat production is to be expected. By overrating the components in your design you can keep this minimized.

Power Supply Basics

The function of a power supply is, of course, to supply power at the correct voltage and current levels to meet the requirements of your project. The energy to run the power supply can come from a number of sources – batteries, solar cells, AC power and others.

The voltages we need for our little electronic devices is generally DC or Direct Current. Batteries also produce DC but line voltages are AC or Alternating Current.  So in addition to providing the correct voltage(s ) an AC power supply also has to convert its AC input to a DC output.


If the above subtitle makes you think of Australian rockers wearing short pants then you are reading the wrong article!

The power that is run into your home is always AC. Alternating Current can be sent over very long distances and stepped up and down using transformers.

The frequency of the AC varies depending upon your location. In North America we use 60 Hz whereas Europe, Australia, New Zealand and many Asian and African countries use 50 Hz.  The voltage levels also are different, North American homes have line voltages around 110 – 120 volts AC while other locations in the world use a higher 220 – 240 volts AC.

If you are building or buying a power supply for a device that you hope to export commercially you’ll need to consider the different line voltages and frequencies around the world. There are also different standards for the type of connectors or plugs used in different countries.

As our electronic devices require DC current at much lower voltages you’ll need to do two things before you can employ the power from your wall outlet:

  • Reduce the voltage to a lower level.
  • Convert it from AC to DC.

Interestingly the above can be done in either order.

In a conventional linear power supply the AC voltage is first passed through a transformer which lowers it substantially, it is then converted to DC.

In a modern switching power supply (like the one in your desktop computer) AC voltage is directly converted to high-voltage DC and this is used to drive a high-frequency oscillator. The high-frequency AC produced by this oscillator is then passed through a small transformer and the low voltage output from that is converted to DC.

Either way at one point we need to convert the AC into DC.  That’s actually pretty simple.

Rectifiers and Bridges

The term “rectifier” dates back to the days of vacuum tubes, it’s really just another name for a high-current diode.  A diode, as I’m sure you already know, is a basic electronic component that will only allow current to pass in one direction.

If you stick a rectifier or diode in series with an AC voltage source you’ll prevent either the positive or negative portions of the AC signal from passing, depending upon which way you orient the diode.

This is a step to producing DC voltage from AC, but the resulting output isn’t exactly smooth as illustrated below.

Half Wave Rectifier

An electrolytic capacitor can be used on the output in an attempt to smooth out the voltage and produce a reasonably steady DC voltage. It’s a simple way of converting AC to DC with a couple of drawbacks.

  • The output voltage will be reduced. It will be the AC input voltage multiplied by 0.7072.
  • You are essentially “wasting” half of every AC cycle, so it’s not terribly efficient.

A better method is to use four diodes to create what is referred to as a “bridge rectifier”.  You can see the results in the following diagram. Again we will use an electrolytic capacitor to smooth out the resulting DC voltage.

Bridge Rectifier

This method has several advantages over the single diode method:

  • The output voltage is greater. It will be the AC input voltage multiplied by 1.414.
  • You are using both the positive and negative parts of the AC cycle, which is much more efficient.

You can either build this circuit with four individual diodes or you can buy a bridge rectifier that is prewired.

By the way, the output voltages I quoted earlier are not quite accurate, you also need to factor in the voltage drop for the diode(s). Generally this is about 0.7 volts.

These circuits will convert AC into DC voltage, however they do nothing to regulate the voltage. If the AC voltage should rise or drop then the corresponding DC voltage output will change by the same magnitude.

Regulators and Converters

Regardless as to whether your DC voltage was derived from AC or whether it is from a battery chances are that it won’t be the correct voltage for your application.  You’ll need to change the voltage to the desired level (i.e. 5 volts) and you need to ensure it stays at that level even if the input voltage changes.

We can do this a few ways using either regulators or convertors.

Linear Voltage Regulators

A linear voltage regulator takes a DC voltage input and produces a regulated output at a lower voltage.

An excellent example of a voltage regulator in use is on the Arduino Uno board. The Arduino Uno has a 5-volt linear voltage regulator on its circuit board, allowing you to use its coaxial power connector to connect a power supply of 8 to 20 volts DC. The regulator reduces this to the 5 volt DC level that the Arduino uses.

Linear voltage regulators have been available since the mid 1970’s and they are still valuable components today. They are very easy to use and are available with different current ratings. They are generally packaged in the same form factor as transistors and power transistors.

Voltage Regulators

Linear voltage regulators typically require an input voltage at least 2.2 volts higher than the desired output voltage. While they can generally withstand a wide range of input voltages you need to aware that the higher the input voltage the more energy the regulator will need to dissipate as heat.

Linear voltage regulators are inexpensive and ideal for line powered devices. They are also used in audio equipment as they don’t create the electrical noise that voltage converters do. While you can certainly use them with battery powered designs they are generally not the best choice for this application as you’ll end up wasting a lot of energy in the form of heat.  This isn’t always true however as there is now a new generation of low voltage drop regulators, we wil be looking at a few of these in a moment.

A better way to regulate voltage(s) in battery powered devices is to use a voltage converter.

Voltage Converters

There are actually three types of voltage convertors that you can make use of in your projects:

  • Buck Converters
  • Boost Converters
  • Buck Boost Converters

Let’s take a quick look at what the differences are between them.

Buck Converter

Buck Converters work using something called a “flywheel circuit”.  In operation a transistor is switched on and off and its output is fed through an inductor (coil) and then to a capacitor.  As the transistor is switched on and off the capacitor charges and discharges the energy that is stored in the coil. The period or frequency that the switching occurs at determines the output voltage.

Buck Converters

Like a linear regulator a buck converter is used in situations where the desired output voltage is lower than the input voltage.

Boost Converter

A Boost Converter works in a similar fashion to a buck converter, the difference being in the arrangement of the coil, diode and capacitor that form the flywheel circuit. Boost converters are also referred to as “switched mode power supplies”.

Boost Converters

As its name might imply the output voltage from a boost converter is actually higher than the input voltage.

Buck Boost Converter

Almost the best of both worlds, a Buck Boost Converter uses a pair of transistor-controlled flyback circuits to either boost or reduce the incoming voltage.

Buck Boost Converters

This type of voltage converter is especially useful for battery powered devices. For example, let’s take a circuit that requires 5 volts and that we wish to use a 7.2 volt battery with.  When the battery is fully charged the converter acts like a buck converter, reducing the output voltage to 5 volts. When the battery discharges itself below the 5 volt level the circuit acts like a boost converter, raising the output to 5 volts.

We will be looking at all three types of converters.

Popular Regulators and Converters

Now that we have discussed power supplies, regulators and convertors it’s time to put what we have learned into practice.

I’ve gathered together several examples of these devices to show you. All of these are simple and inexpensive methods of providing voltage for your project.

Linear Regulator – 78XX and 79XX Series

Our first linear regulator is a component that has been around for over 40 years. Actually it’s a family of components whose members have different voltage outputs and current capabilities.

The 78XX voltage regulators are 3-pin devices available in a number of different packages, from large power transistor packages (T220) to tiny surface mount devices.  These are positive voltage regulators, the most common type. The 79XX series are the equivalent negative voltage regulators.

The numbering system for these components is pretty simple, the XX in the part number indicates the output voltage. So, for example, a 7805 is a positive 5 volt regulator, a 7812 is a positive 12 volt regulator and a 7915 is a negative 15 volt regulator.  Both the positive and negative series are available in several common voltages.

78XX Voltage Regulators

These voltage regulators are pretty easy to use. Other than the regulator itself the only additional components you’ll require are a couple of electrolytic capacitors across the input and output. The values are not critical, generally a 2.2uf or greater capacitor can be used on the input and a 100uf or greater one on the output.
Note that although you use both the positive and negative regulators in the same way the pinouts are different:

The 78XX (positive) regulators use the following pinout:

  1. INPUT

The 79XX (negative) regulators use the following pinout:

  2. INPUT

One thing to note about the TO-220 case version of these voltage regulators is that the case is electrically connected to the center pin (pin 2). On the 78XX series that means the case is grounded but please note that on the 79XX (negative regulator) series pin 2 is the input, not ground. This means you need to use caution when connecting a heatsink to the device, which you will need to do if you plan on drawing a lot of current.  If necessary you can use a mica insulator on the heatsink to keep it from electrically contacting pin 2.

Despite their age these regulators are still very much in use today and are good for line-powered designs. They are not as efficient as modern regulators however so for battery powered devices you’ll want to look at some of the other solutions presented here.

Linear Regulator – LM317 Variable Regulator

The LM317 is a positive linear voltage regulator with a variable output. This is also a classic electronic component and its variable output makes it very useful in situations where you need a “non-standard” voltage. It has also been popular with hobbyists for use in simple variable workbench power supplies.

As with the 78XX series or regulators the LM317 is a three pin device. The wiring however is a slight bit different, as illustrated here.


LM317 Variable Voltage Regulator

The main thing to note about the LM317 hookup is the two resistors that provide a reference voltage to the regulator, this reference voltage determines the output voltage.  You may calculate these resistor values as follows:

The recommended value for R1 Is 240 ohms but it can actually be any value from 100 to 1000 ohms.

Of course you can also substitute a potentiometer for the two resistors to make a variable linear voltage regulator. You would probably want to put a 100 ohm resistor in series with the potentiometer to be sure that R1 never goes down to zero ohms.

As with the 78XX series of regulators the LM317 is still in use today but again there are more efficient regulators now available. Still it would be a good choice for a line powered power supply that needs an “oddball” voltage.

Linear Regulator – PSM-165 12v to 3.3v Linear Step Down Regulator

The PSM-165 is a small breakout board that contains a 3.3 volt regulator. This tiny board will take an input of 4.5 to 12 volts and convert it to 3.3 volts for low powered logic circuitry.

The chip used on the PSM-165 is the same one used on most Arduino Uno boards to supply a 3.3 volt output. It has a maximum current capability of 800 mA.

The board is interesting in that it has multiple connections for both input and output, this provides a lot of flexibility when designing a PCB that uses this module as a “daughterboard”.

PSM-165 Voltage Regulator Module

As you can see the hookup for this module is very easy, no external components are required.

Linear Regulator – AMS1117-5 Linear 5v Regulator Module

The AMS1117 series of three pin voltage regulators operate a lot like the 78XX series.  They are available in several different voltages and are pin compatible with the 78XX series.

These are more modern devices than the 78XX series and feature a lower voltage drop, making them useful for both line-powered and battery-powered supplies.

The AMS1117-5 is a 5 volt regulator. It’s available by itself or on a popular breakout board. The breakout board makes it very simple to incorporate into your project.

AMS1117-5 Voltage Regulator Module

As with the PSM-165 hookup of the AMS1117-5 module is a breeze.  The breakout board has the filtering capacitors on it so no external components are required. Just hook up your input voltage and draw power from the output – it’s that easy!

Linear Regulator – L4931CZ33-AP 3.3v Very Low Drop Regulator

The final linear voltage regulator that we will look at today is the L4931CZ33-AP. As with the PSM-165 this regulator provides 3.3 volts to power low-powered logic circuitry.

This regulator has an extremely low voltage drop, a mere 0.4 volts to be exact. This makes it an ideal regulator to use in low-current battery powered devices.  It’s also extremely tiny, available in a TO-92 transistor package as well as in several surface mount packages.

The L4931CZ33-AP is actually a member of a family of low voltage drop regulators, there are also 3.5, 5 and 12 volt models with similar characteristics. The only additional component required when using this device is a small 2.2 uF electrolytic capacitor.

L4931CZ33-AP Voltage Regulator

The hookup of the L4931CZ33-AP is a lot like that of the 78XX series. The 2.2uf capacitor I mentioned is used on the output, you can also place an optional ceramic capacitor on the input.

Buck Converter – MINI-360 DC-DC Step Down Buck Converter

Now let’s look at a buck converter.  The MINI-360 is a super tiny, super efficient buck converter that can accept inputs of up to 23 volts and deliver an output that can be adjusted down to as low as 1 volt and as high as 17 volts.

The device is on a very tiny breakout board that has a potentiometer for setting the output voltage.  With an efficiency of around 95% very little energy is wasted as heat, making this device an ideal choice for battery-powered designs.

MINI-360 Buck Converter

As shown in the diagram the hookup of the MINI-360 is very simple, just hook up your input voltage and it’s ready to use. It would be a good idea to adjust the potentiometer and set the output level before you connect any load to it, especially if you plan on using it for a low voltage.

Boost Converter – PSM-205 Step Up 5v USB DC-DC Converter

The first boost converter that we will look at is a unique device in that it has a USB jack integrated on the breakout board. This is very convenient when building a supply for a USB powered device.

This inexpensive module will boost a voltage as low as 0.9 volts to 5 volts at up to 600 mA. Obviously this is ideal for projects powered by batteries, a single AA or AAA cell can now be used to power your 5 volt logic devices.

PSM-205 USB Boost Converter

Again the module makes for a very easy hookup, you literally connect a source of 0.9 to 5 volts to the input and plug your USB powered device into the USB connector.

As you may have already guessed this boost converter is often used in USB power banks.

Boost Converter – MT3608 DC to DC Step Up Converter

Another tiny boost converter, the MT3608 can take an input as low as 2 volts and raise it to as much as 28 volts. It includes under-voltage lockout, thermal limiting and over-current protection.

The MT3608 is packaged on a tiny breakout board with a trimpot for setting voltage levels. While it might look tiny this device can source an impressive 2 amperes of current. The MT3608 has an efficiency rating of 93%.

MT3608 Voltage Boost Converter

With only four clearly labeled pins the MT3608 is very simple to use. As it is capable of outputs of up to 28 volts it is a good idea to use the trimpot to set the output voltage before connecting the device to your circuit.

Buck Boost Converter – S9V11F5 Step Up/Step Down Regulator

Now we move onto a device that is my personal favorite for battery powered devices – the S9V11F5 Step Up/Step Down Regulator.

Made by Pololu this little wonder can produce 5 volts with an input ranging from 2 volts to 16 volts. One thing to note is that the voltage needs to be at least 3 volts to get the converter started but once it’s running the input voltage can drop to 2 volts before it stops working.

This board is very small and has only three connections. It is packaged with both straight and right-angled male headers, allowing you to use it in the same place as a traditional 3-pin linear regulator.

The S9V11F5 is a member of a family of breakout boards, some with fixed output voltages and some that are variable.

S9V11F5 Buck Boost Converter

The S9V11F5 does not require any external capacitors or other components to get it to work. It’s super small size and relatively high output current capability makes it ideal for many designs.

One thing to be aware of however is that the S9V11F5 can get quite hot, especially when used at full current capacity. Keep that in mind when you lay out your circuit board and don’t touch the converter when it is in use, you could burn yourself!

Breadboard Power Supply

Before we finish I want to mention one more method of powering up your projects.

The Breadboard Power Supply is a common component that is designed for, you guessed it, powering solderless breadboards.  These inexpensive units have two linear regulators onboard to provide a steady 5 and/or 3.3 volts from a 9 – 15 volt dc input. They are designed to snap into the power rails of a standard solderless breadboard.  The unit also features a 2.1 mm coaxial power input, power LED indicators, a USB power output and an on/off switch.

While these devices are obviously meant for use on the workbench with solderless breadboards they can also make a fine power supply for a permanent project.  A they use linear regulators they are probably more suited to line-powered designs although they can be powered with a 9 volt battery.

Breadboard Power Supply

I’d recommend having a few of these around your workshop, if only for experimenting.

In Conclusion

Providing a good source of power is an essential part of designing electronic devices. As you have seen there are many methods you can use to provide a source of power for your electronics projects.

If you intend to use line (AC) power to provide electricity for your device you need to be sure to take the proper safety precautions to prevent any chance of electric shock. The best method of doing this is to use a commercial AC adapter or “wall wart” to provide a safe source of DC power, which you can then regulate using one of the methods described above if necessary.  Using a commercial adapter that has been certified for use in your country (i.e UL approval, CAS approval etc.) will also satisfy insurance requirements, a very important factor especially if you intend to mass-produce your design.

For battery powered designs the use of an efficient voltage converter can extend the running time of your project by squeezing every last drop of energy from your batteries before require recharging or replacement.

No matter what your requirements are you’re sure to find a converter or regulator to suit your needs.

Now let’s get powered up!


Parts List

Here are some components that you might need to complete the experiments in this article. Please note that some of these links may be affiliate links, and the DroneBot Workshop may receive a commission on your purchases. This does not increase the cost to you and is a method of supporting this ad-free website.




78XX Family Spec Sheet – Datasheet for the 78XX family of linear voltage regulators.

LM317 Spec Sheet – Datasheet from Texas Instruments for the LM317 linear variable voltage regulator.

AMS1117 Spec Sheet – Datasheet for the AMS1117 linear voltage regulator.

Si9172 PSM Buck Converter – Spec sheet for the integrated circuit in the PSM-165

MP2307 Step-Down Converter – Datasheet for the integrated circuit in the MINI-360 Buck Converter.

Low Dropout Linear Regulators – The design behind the L4931CZ33-AP and other regulators in its family.

MT3608 Spec Sheet – Datasheet for the integrated circuit in the MT3806 boost converter module


Powering Your Electronics Projects – Voltage Regulators and Converters
Powering Your Electronic Projects - Voltage Regulators and Converters
Article Name
Powering Your Electronic Projects - Voltage Regulators and Converters
Learn to provide a stable source of electricity for your electronic projects. In this article we wil discuss the hookup of several popular voltage regulators and converters.
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DroneBot Workshop
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Krzysztof Rogoża
5 years ago

Can You make tutorial about Bistable flip-flop switch for arduino? My project have a week spot, this spot is that arduino is powered all the time from batery. I s for me dificult to use internal sleep mode, and still arduino will take a lot of curent. Thats why i have idea for flip-flop state module, that with switch I can power on my arduino, and after one minute, pin from arduino can send signal to flip-flop module to shut down everything. I think that this way can be very oficient in use. My project is about mesuring water in… Read more »

Steve Tripoli
5 years ago

Thank. Very good information on 5volt power supplies. One question is how stable is the output voltage of the buck boost regulator to a varying load?

John Doggett
3 years ago
Reply to  Steve Tripoli

I have been using the buck boost regulator for a while now on a few projects.
The voltage does move slightly, by very small amounts but I have found that the Uno and the nano cope with them very well.
I have also started using power banks for battery supply to projects. They are cheap and can last longer than batteries and come in various sizes.
Hope this helps

Mariano Alaniz
5 years ago

Thank you Sir. My robot car building endeavors can be achieved. I had problems with the motors not having enough juice, but your lecture has given me a new hope.

Gopal Patil
5 years ago

Thank you so much sir for the useful info.
Your all the videos and tutorials are very clear, to the point and elaborative. It is quite difficult to understand electronics for the guys like me who is having mechnical engg background.
I love the way you describe the topic by first understanding need, describing basics behind it, basic circuit and then advanced things.
I am fan of you.
Keep it up sir.
Jug Jug Jiyo! (Hindi words for : live forever)

ryan regivan
5 years ago

thank you so much for this article and videos, sir.
all information thats your describes on video and article helping me to understand about voltage regulator, because i make thesis to analysis comparison of voltage regulator. and this article are good. because, the article you wrote, contains scientific writing.

5 years ago

Thank you. This is amazing

Ken Shaw
5 years ago

Very clear explanation – thanks!

D g nmkk
5 years ago

A clear and good explanation thanking you for the efforts . Electronic industry is not known because of no proper communication……. it is great effort by you…..

4 years ago

Thanks for a VERY GOOD summary of the power supply as it applies to Arduino.
The LM317 heat sink tab is internally connected to Vout: making it necessary to use an insulator when mounting it on a metal heatsink which is usually at Ground .

PLease make a note os this so that viewers don’t forget about the danger of creating short circuits between the LM317 output and a grounded heat sink.

4 years ago

Hey your videos are great I’ve watch and learn lots. So if I wanted to add a USB charger to a 12V LED circuit I’d use AMS1117-5?

3 years ago
Reply to  Eric

I’d use a buck converter for that. Charging with a linear supply is not ideal, there’s going to be a lot of wasted energy in the form of heat.

sivakumar manivannan
4 years ago

u r a great teacher, i feel lucky to find u ,Thank you & keep teaching

James A Forrest
4 years ago


Alan Brewster
3 years ago

Thank you for your presentation. You have started my interest in electronics and you inspire me to learn more. Thanks again.

3 years ago

Thanks for your helpful knowledge for todays needful and it is extremely beneficial and briefed topic.My almighty God may bless you with great pleasure and honour and pic you in his beloved ones.Thanks for your experience and knowledge for the generation of MY ALMIGHTY GOD.

Dalyop petr
3 years ago

Please can you write a tutorial on how to read to read tl494 power ic .

3 years ago

Short and to the point. Waiting on my first arduino starter kit.Very rural area, still waiting. 90vdc 1/3 HP 3.5a permanent magnet gearmotor 500 RPM. I need to create a power supply and control by RF. I have read about every Dronebot Workshop tutorial I can find, (videos as well). I could just buy a controller but, that’s not learning to solve problems. right? CNC, fabrication and welding background. Advice welcome.

3 years ago


I made the output voltage calculation for LM317 that you have used in the video, and I have found that the output voltage based on the resistor you mentioned should be 5.9 V DC, not 4.8 V DC.
Here is the calculation:
R1 = 220 Ohm
R2 = 820 ohm
Vout = 1.25 x (1 + (R2/R1))
Vout = 1.25 x (1 + (820/220)) = 1.25 x (1 +(3.73)) = 1.25 x 4.73 = 5.9 V DC

Can you please clarify if there is anything I am missing or your calculation is wrong?

Thank you in advance,

3 years ago
Reply to  Dervis

Seems there’s a minimum load requirement for the LM317. One LED should be enough to satisfy the minimum load, as they are typically ~20 mA for a small LED. From the On Semiconductor datasheet: Electrical Characteristics: Minimum Load Current to Maintain Regulation ILmin Typ: 3.5 mA Max: 10 mA Application Information: The LM317L is a 3−terminal floating regulator. In operation, the LM317L develops and maintains a nominal 1.25 V reference (Vref) between its output and adjustment terminals. This reference voltage is converted to a programming current (IPROG) by R1 (see Figure 13), and this constant current flows through R2 to… Read more »

3 years ago

Do you also know a DC-converter from 36V (Bosch PowerPack 500) to 5V for Raspberry PI ?

3 years ago
Reply to  Xavier

If you just want the chip, ME3116AM6G, XL1509-5.0E1 LM2596R-5.0 would likely work (There’s lots of clones of the LM2596). That’s just a few options. They have a max voltage input of 40 or 45v. Keep an eye on the max current for your applications. You’ll likely want to have some headroom rather than go right up to the maximum. You’ll need to design a board around these chips along with deciding supporting passive components. Datasheets can help you with that. There’s also modules that uses these chips out there. different companies will use different part number.

3 years ago

I’ve been subscribed for a while, but I thought I would leave a comment to say thank you for an amazingly detailed but beginner accessible tutorial on voltage regulators. I like the style of your videos because it covers all the information, but doesn’t leave out of any of the important technical bits and I also love that you put out a full article on your website, which can be referred to like a cheat sheet, so you don’t need to keep flicking through the video if you want to refer to it while you’re in the workshop. 🙂 Maybe… Read more »

3 years ago

Help with battery power suggestion battery type set up what I am looking at right now is two separate batteries. I am running a YBJ-48 Stepper Motor constant one way and an adurino uno. The stepper motor is I think is half stepping 2048 steps per revolution.

I would like to run it for an hour or longer, it will be outside possible cold tempartures.

Matheo Koning
3 years ago

is the S9V11F5 stil for sale? Can not find it on the cheaper website’s.

2 years ago

hi im Nhlaka i live in South Africa. Im very interested in working on a innovation

Richard Lane
2 years ago

Thank you, that’s a wonderful explanation of all the ways to power your projects. It would be great if you do a video on powering projects from a small solar panel and rechargeable battery using something like a buck/boost converter on the battery output.
Keep up the great work!

Robert Hatcher
1 year ago

I love your website and videos, thank you so much for all the great info!