Introduction: Step-up Booster

Picture of Step-up Booster

This is a DC-to-DC Step-up Booster circuit (Input 3.5V-13V) to 12VDC / 1.5A Output

Step 1: Introduction

Picture of Introduction

The schematic is from the

I encourage you to pay a visit as there are lots of useful schematics to use freely.

All I did was to draw the PCB layout and test the circuit which works perfectly well.

Lets get started.

A Step-up circuit receives a lower voltage and produces a higher Output to be used where that higher voltage is not available. Step-up boosters have lots of uses with most common on battery operated applications.

This is a DC-to-DC converter. The Input voltage can be as low as 3.5V – 13V DC and can provide 12VDC Output.

A Li Ion Battery of 3.7V nominal voltage can drive this circuit to provide an Output of 12V / 1.5A.

Step 2: Components

Picture of Components

There are no critical components here except perhaps for the ferrite coil as a ready made choice which is easy to construct it by yourself as I did. The main component is the IC= MC34063 which simplify the whole circuit as it requires only a few extra components to operate.

The MC34063A Series is a monolithic control circuit containing the primary functions required for DC−to−DC converters. These devices consist of an internal temperature compensated reference, comparator, controlled duty cycle oscillator with an active current limit circuit, driver and high current output switch. This series was specifically designed to be incorporated in Step−Down and Step−Up and Voltage−Inverting applications with a minimum number of external components.

Advantages of MC34063A

• Operation from 3.0 V to 40 V Input

• Low Standby Current

• Current Limiting

• Output Switch Current to 1.5 A

• Output Voltage Adjustable

• Frequency Operation to 100 kHz

• Precision 2% Reference

All Resistors are 1/4W.

[T] TIP31 is a NPN power transistor. All Amperage Output passes through it.

[L1] 100μH ferrite coil. If there is a need to construct it by yourself purchase a toroidal ferrite of outer diameter = 20mm x inner diameter hole= 10mm x 10mm high and a wire of 1mm – 1.5mm width x 0.5miter long and make 5 tight turns in equal distances. Ferrite dimensions are not so critical. A difference of a few (1-3mm) on the above dimensions will be ok.

[D] A Schottky Barrier Diode must be used.

[TR] A multiturn PCB trimmer used here to fine tune the Output voltage as close to 12V.

[C] C1 & C3 are Polarity Capacitors so pay attention when placing them on PCB.

Step 3: Parts List

Picture of Parts List


R1 = 0.22 Ohm x1

R2 = 180 Ohm x1

R3 = 1.5K x1

R4 = 12K x1


TR1 = 1K multiturn PCB trimmer x1.


T1 = TIP31A or TIP31C x1


L1 = 100μH Ferrite Coil x1. See text above for more info.


D1 = Schottky Barrier Diode. 1N5821 (21V - 3A) or 1N5822 (28V – 3A) or MBR340 (40V – 3A) x1.


C1 = 100μF / 25V X1.

C2 = 0.001μF (102 code) x1

C3 = 2200μF / 25V


IC1 = MC34063 8 PIN IC & 8 PIN DIP socket.


PCB board 55mm high x 41mm width x1.

Update: after @ClockworkPheonix suggestion i have re-draw the PCB (Vr:02) which now is 58mm high and 41mm width. Also the wire connection close to T1 have been removed. Υou may choose the PCB that suits you best.

2 PIN PCB Terminal Block x2.

A Solid Core wire of 1 – 1.5mm x 50mm.

If you notes excessive heat at the T1= TIP31 a small aluminum heat sink must be mounted otherwise the transistor may be damaged.

Step 4: Construction

Picture of Construction

I have included enough pictures to follow. If it is to use the Iron - Steam Iron method, print the PCB layout the way it is. Do NOT flip the image and do NOT use steam!

Not all of us know how to use a CAD application, so to make it easier there is a BMP lossless image of the PCB layout in files section to print preferably using a laser printer. The exact dimensions of the PCB are 55mm x 41mm. You can use the print preview of the Corel Photo Paint for example to dynamically re-size the PCB layout to meet the exact dimensions before printing.

This is by far not the best way to print a PCB layout but for traces at that size works just fine for any amateur enthusiast. So, go ahead and make it!


mathewriver (author)2015-01-24

So I need to feed a 10w LED (900ma) with this circuit. How long would the battery (A 3,7v 3100mA lithium battery) hold?

frapedia (author)mathewriver2015-01-29

given the battery's capacity i wouldn't expect more than 2h - 2.5h

mathewriver (author)frapedia2015-01-29

If I use 3 batteries at once (3,7v 5600mah each), will the system still output 12 volts with 1.5 A? How long do you think it would last? By the way, is there anyway to decrease the voltage and current to 11v 1A?

frapedia (author)mathewriver2015-01-31

Regardless of how many batteries you connect in parallel will always output the battery nominal voltage which is 3.7V for Li-ion bat. What you gain using batteries in parallel is the capacity, meaning longer operation time thus the circuit will operate for longer time. So, yes the circuit will still output 12V.

As about current you don't have to worry. What's important here is the LOAD and how much current draws. If the connected device (LOAD) draws say 100mA then all the system will operate for much longer time.

If theLOADrequires 11V you can adjust the [TR] trimmer or even replace the [R4] to the next lower value.

mathewriver (author)frapedia2015-01-31

Hey there, sorry, I forgot to specify. I'm going to use the batteries in series, not in parallel. About that current consumption, I'm sure because I'm going to use a LED, and everywhere is saying it should have only 900ma (max) of current and 11volts.

antonius.vincent.9 (author)2014-11-29

is it possible if i connect it to 5V 2A???? how much output i get???? please help

NO. 2A are way out of range for Q1 for safe operation even if you add a heatsink.

Bryanmatthew7 (author)2014-10-11

everytime I try to print the PCB layout, it enlarges the image to the full size of the page. Now I can resize the image in Microsoft paint but I don't know what dimensions to use. How did you print it?

frapedia (author)Bryanmatthew72015-01-29

The new PCB dimensions are 58mm high and 41mm width. You can use corel photo-paint print preview to resize the image at the given dimensions.

JayJ57 (author)2017-09-18

What is the maximum current that i can supply at the input to get 1.5A current at the output

zorba02008 (author)2017-05-21

can i use another equivalent for this transistor TIP31A or TIP31C like TIP41

jawadsahibzada (author)2017-01-29

can i use Three 1N5819 (30v 1A) diodes in parallel to make it equal to 1N5822 (30v 3A)

jawadsahibzada made it! (author)2017-01-29

i made it !! it's great but i can't find 1N5821 diode, instead i used 1N5819, now it works but current is low and voltage is perfect,

arick (author)2016-12-16

How can I get 220V 0.2A on the output ?

arick (author)2016-11-29

how can I get 0.1A with 220V ?

ThôngV4 (author)2016-10-16

I have a lithium-ion battery with max current 5A and voltage 3.7V
1) could I use this circuit to output a stable 12V/1.5A?

2) could I make this circuit with surface mounted resistors and capacities
Thanks a lot.

aerospaceeng (author)2016-03-28

Hello dears
Due to no electricity here I bought a solar panel of 150w which is charging a battery of 100 Ah. When I want to operate a led screen TV 12V, 50W 22" wide. It operate normally till the controller reads 12.2 V it shows low battery symbol 1℅ then stops.
How can I fabricate a circuit to step up the voltage to constant 12.3 V , 2.1 A regardless of the actual voltage in battery.

SabaR4 (author)2016-03-27

i want to find out that how much the current will get lost a percentage would be good from the input voltage current lets say i have a solar panel which is 5v and 3.5A and i us a step up voltage to 12v but how much is going to be the amps

SabaR4 (author)2016-03-27

i want to find out that how much the current will get lost a percentage would be good from the input voltage current lets say i have a solar panel which is 5v and 3.5A and i us a step up voltage to 12v but how much is going to be the amps

SabaR4 (author)2016-03-27

i want to find out that how much the current will get lost a percentage would be good from the input voltage current lets say i have a solar panel which is 5v and 3.5A and i us a step up voltage to 12v but how much is going to be the amps

SabaR4 (author)2016-03-27

i want to find out that how much the current will get lost a percentage would be good from the input voltage current lets say i have a solar panel which is 5v and 3.5A and i us a step up voltage to 12v but how much is going to be the amps

RalphR15 (author)2016-03-04

I need a little help on a project im doing i have 2 AA batteries going into a .9 to 5DC stepup into a 3 to 12DC 1A output how can i stepup Amps from 1A to 18A with out losing 12DC thanx

ShadmehrA (author)2015-12-13


spudziuvelis (author)2015-12-05

your coil looks nothing like 100uH

LP700-4 (author)2015-10-20

I want to power it with a rc car LI-Po battery and it is 7.4V 3400mAh, what changes should I make so that it could work?

G.H.Q.D.mafiaWolf (author)2015-09-12

Could you provide me the max current of the Inductor?
And.. 1,5A is peak or continuous current?

Adrian1101 (author)2015-07-01

Awesome project, have a small problem tho, my power source is 4x duracell AA 2400mah batteries, I am using the circuit to power a 12v 3w led bulb, the bulb draws 238ma and the whole setup works well except for the tip 31 transistor getting hot within a few minutes even with a decent heat sink, this loss of efficiency causes the batteries to run flat in an hour and twenty minutes, have set the 1k trimmer to the lowest voltage setting, no luck, what am I missing here? Any advice would be much appreciated.

人豪陳 (author)2015-05-08

Dear sir :

I've seen your article of step up booster using MC34063a , and made a similar boost converter .I use TIP31C instead of TIP31A,and 1N5822 instead of MBR340.

Now I'm facing a problem that when I connect to a 12 ohm load, the output voltage will decrease to 8 volt, even 6 volt . so I cannot reach the target of Vin=5V ; Vout=12V , Iout=1A request.

It seems like there are some elements which limited my output power , I'd very appreciated if you can give me some advice. Thank you very much.

JokerA (author)2015-03-29

Can we this circuit to make the car's cigarette heater work ? or there is a sufficient in A.s?

mathewriver (author)2015-02-12

What do I need to change to increase the input voltage to 35 volts.

catacris2003 (author)2014-08-30

0.22R rezistor or 220R ?

frapedia (author)catacris20032014-09-14

it's 0.22r

hotshot_87 (author)2014-06-25

Is it possible to get an output of 15v from the circuit, the current can be around 1A?

What do I need to change I guess the inductor, not sure of the value. Is there anything besides it that needs to be changed?

salexandridis (author)2014-05-11

Sygxarhthria gia ena akomh yperoxo Instructable!

frapedia (author)salexandridis2014-05-11


se eyxaristw file moy :)

knaggs (author)2014-05-10

Very useful one question I have though, can I adapt it to input 12v and output 24v to run about 150w? My dc knowledge comes mostly from automotive and the fine details sometimes escape me when it comes to the small electronics. It would be awesome to run 24v military style lighting in an off-road application.

nqtronix (author)knaggs2014-05-11

After a quick look at the datasheet of the MC34063A I'd say it's
definitly possible to archive an output power of 150W, since the IC is
only a controll circuit and all the power is handled by external
components. However stepping up 12V to 24V at 150W isn't a trivial task,
because it has to be able to handle high currents (150W / 12V = 12.5A).
This makes a carefully choise of inductor, transistor and diode
essential. You should also pay attention to a suited layout, the tracks
should be realy wide (at least several mm). Whenever working with high
power the efficiency matters a lot, because all waste will be converted
into heat, which require bulky heatsinks (and fans).

If your're
not into electronics that much I'd strongly recommend to look either for
a different circuit (which is proven to work) or get an allready
assembled module/ device. It will save you lots of time, costs about the
same and safe you a lot of frustration. If you however intend to learn
something and want to invest (a lot of) time on research an development,
you'll be surprised how well it'll turn out. Good luck with your
projects whatsoever.


@frapedia You've done a nice job. Selfmade circuits/pcbs are pretty rare on instructables, so I highly appreciate your work. Thumbs up, dude!

However keep in mind for the next project that whenever you expect high currents you should make the tracks extra wide, this decreases the resistance and improves the efficiency. For the same reason you should also try to keep the tacks as short as possible, two corners of 45° reduce the length by about 30% compared to a 90° corner. This way it will also look instantly more professional ;)

frapedia (author)nqtronix2014-05-11


Thank for the info!

However, this board is made to handle no more than 1.5A as stated so traces of 2-3 mm soldered are quite capable for that load. As about the use of 45° corners and shorter lengths you are right.

frapedia (author)knaggs2014-05-10

Hi knaggs,

The output of this circuit is 12V / 1.5A (2.5A SAFE MAX). At 1.5A is about 18W and at 2.5A is about 30W. So, it's output it way less than the 150W you ask for.

Perhaps adding another or more power transistor(s) which it could handle the wattage will work out.

ClockworkPheonix (author)2014-05-11

If you make your board slightly bigger (go up at the top and connect the 3rd pin to the far left of the board) you can avoid having to use the two wires


lol... you are absolutely right, i should of draw it that way. i'm gonna fix it.

Jan_Henrik (author)2014-05-11

very cool!

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