0 Simple 12V to 24V Converter

The use of this circuit is similar to 12V to 24V converter ver1 that is to increase voltage to 24V. This converter can deliver an output current around 500mA and uses only op-amp and transistor, thus very cheap to construct. You can calibrate the output voltage by simply adjusting the potentiometer R7.

12V-24V dc-dc schematic

Part List:

R1, R2, R3, R4, R6, R8 - 120 kilo ohms 1/4W

R5 - 560 ohms 1/2W

R7 - 10 or 20 kilo ohms potentiometer

C1 - 10nF Mylar capacitor

C2 - 100nF Mylar capacitor

C3 - 330uF electrolytic capacitor rated 75V

D1 - 1N4007 or similar diode 

D2 - 1N4937 or similar fast recovery diode

L1 - 2mH inductor rated 1Amp  minimum

Q1 - 2N2102 or similar NPN transistor
IC - LM358 or similar op-amp

2N2102 pinout

LM358 pinout

Similar Circuits:
12V to 24V converter using 555
12V to 48V converter

0 Regulated Negative Power Supply using 79xx IC

This is a regulated negative power supply circuit using the 79xx IC series. These regulators can deliver current around 1.5A at a fix negative voltage. The common regulated voltages are -5V, -6V, -8V, -9V, -10V, -12V, -15V, -18V, and -24V. The regulator IC is the complement of 78xx regulator IC.

Negative power supply schematic

Part List:

T1 - see minimum input voltage below for reference

D - rectifier diode rated 2A with minimum voltage of 50V

Cin - 220uF electrolytic capacitor (- to IN and + to GRND)

Cout - 10uF electrolytic capacitor (- to OUT and + to GRND)

The table below is the list of regulator IC and the minimum input voltage required to maintain the output voltage.

Input voltage table

79xx IC come in TO220 casing. The pin connection is shown below.

TO220 casing

Pin 1 is the "GRND" pin, pin 2 is the "IN" and pin 3 is the "OUT" pin. Take note that these pins are different from the pins of 78xx IC series since "IN" and "GRND" pins are interchanged.

0 Regulated Power Supply using 78xx IC

This is a regulated power supply circuit using the 78xx IC series. These regulators can deliver current around 1A to 1.5A at a fix voltage levels. The common regulated voltages are 5V, 6V, 8V, 9V, 10V, 12V, 15V, 18V,  and 24V. It is important  to add capacitors across the input and output of the regulator IC to improve the regulation.

general schematic diagram

Part List:
T1 - see minimum input voltage below for reference
D - rectifier diode rated 2A with minimum voltage of 50V
Cinput - 220uF electrolytic capacitor (connected across IN and GRND)
Coutput - 10uF electrolytic capacitor (connected across OUT and GRND)

The table below is the list of regulator IC and the minimum input voltage required to maintain the regulated output voltage.

regulator minimum input voltage

78xx IC come in TO220 housing or casing. The pin connection is shown below.

78xx pinouts

Pin 1 is the input pin, pin 2 is the ground and pin 3 is the output pin.

1 High Voltage Variable Power Supply

This circuit is a variable power supply using IC LR12 of Supertex inc. The difference of this circuit compare to variable PSU using LM317 is it can hold a high voltage input (100V) and can deliver an output of around 88V max down to 1.2V. This regulator is very suitable to DC circuits using higher voltage with current less than 100mA. The output voltage is controlled only by R1 and POT using the relationship below:

Voutput = 1.2(1 + POT/R1) + ADJ*POT or just use the LM317 calculator.

regulator schematic

LR12 pinout

Part List:

R1  - 560 ohms 1/4W

POT - 50 kilo ohms potentiometer

C1 - rated above 100V capacitor ( you can remove if DC is regulated)

C2 - 470nF (higher the better) capacitor rated 100V minimum

IC - LR12 or similar regulator IC

Note: The circuit is easy to construct but it is powered by high voltage DC that can be fatal. I dont recommend building this one if you don't have any idea in electronics. Remove only C1 if the DC input is regulated.

1 Power Supply with Selectable Output

This simple power supply unit (PSU) uses LM317 IC and can deliver 1.5A current with selectable voltages. Outputs are 1.5V, 3V, 4.5V, 6V, 9V and 12V. The output voltage is controlled only by the resistor combinations. You can use the LM317 calculator to determine these resistor values.

PSU schematic diagram

317 pinout

Part List:
C1 - 2200uF electrolytic capacitor rated 25V
C2, C5 - 100nF Mylar or ceramic capacitor
C3, C5 - 22uF electrolytic capacitor rated 16V
R1, R2, R7 - 120 ohms 1/4W
R3, R4 - 240 ohms 1/4W
R5 - 100 ohms 1/4W
R6 - 20 ohms 1/4W
D1, D2 - 1N4004, 1N4007 or similar silicon diode
317 -  LM317 or similar regulator IC
S1 - rotary switch
DC - see AC to DC converter circuit below

Part List:
Transformer - 220 to 12V center tap rated 15VA minimum
D - Any rectifier diode rated 2A minimum
C - You can omit since we got C1 (2200uF)

Note: I recommend using 220V/15V center tap but excessive heating might occur on when 1.5V is selected and with 1.5A output. The lower the output voltage with higher current, the higher the tendency the LM317 will overheat.

0 Switchable DC Power Supply

This is a simple way of converting your standard DC source in a switchable power supply unit. Shown below is a simple circuit using a discrete regulator out from a transistor and zener diode combination. The circuit can deliver a maximum current of 1A (higher current if modified) at an output of 3v, 6V, 9V, and 12V.

Regulator schematic

Part List:
R - 56 ohms 5W (3W is the minimum)
Q - TIP41C, 2N3055 or similar NPN transistor
D1 - 1N4728A, or 3.3V zener diode rated 1W
D2, D3, D4 - 1N5225B, or 3V zener diode rated 0.5W minimum
Fuse - 1A fuse
DC input - 14V to 18V DC source

2N3055 pins

TIP41C pins

Note:Transistor must have a heatsink. You can add capacitors across the input and output terminals for better regulation and clean DC output.

8 High current variable power supply (1.2V to 30V at 5A)

We are going to design a simple, very cheap, high power, variable power supply unit (PSU) with current control or protection. Diagram below is our design basis. We have three main parts, the voltage regulator, current amplifier, and current controller. Voltage regulator is the one that controls the variable voltage output, which in our case LM317 IC. Current amplifier is an add-on circuit component that boosts the output current. Current controller is the circuitry that protects the entire power supply unit from short circuits and overloading. You can use either ordinary fuse or current limiter circuit as your current controller.

PSU design

Power supply unit below is rated 150W and has an output current of 5A. Output voltage can be varied from 1.2V up to 30V DC, thus very suitable as power source of your electronic projects, devices, battery chargers and others.

High power PSU schematic diagram

Circuit Operation:

DC input is a 35VDC using AC-DC converter below. R1, Q1, and Q2 limits the maximum to 5A (read more on how current limiter works). Q3 and R3 is the current booster that increases the current capacity of LM317 regulator. R4 is the potentiometer that controls the output voltage from 1.2V to 30V (see LM317 calculator to know how these output voltages are arrived).

Part List:
R1 - 0.15 ohms resistor 10W
R2 - 1.8 kilo-ohms 1W
R3 -  4.7 ohms 1/2W
R4 - 5 kilo-ohms potentiometer
R5 - 220 ohms 1/4W
Q1 - 2N4403 or any general purpose PNP transistor
Q2 - IRF4905 power FET or similar power PMOS
Q3 - MJE2955t or similar PNP power transistor
C1 - 220uF electrolytic capacitor rated 50V
C2 - 22uF electrolytic capacitor rated 50V
LM317 - regulator IC
DC input - regulated 35V DC (see AC-DC converter circuit below)

Part list diagrams: click to enlarge

LM317 pin

IFR4905 pins

MJE2955t pins

 The DC input

AC-DC converter

Converter Part List:
X'former - 220V/27V-0V-27V center tap transformer min 180VA
D - rectifier diode min 6A current rating
C - 1000uF electrolytic cap 50V (higher capacitance the better)
Fuse - 1A @ 220V

Similar variable PSU projects:

1. Simple variable PSU - (+1.2V to +28V at 1.5A) positive output

2. Negative variable PSU – (-1.2V to -28V at 1.5A) negative output

3. Dual variable PSU – two outputs positive and negative @ 1.5A, from 0V to 28V

1 +12V and -12V power supply

This power supply is useful in powering opamps, comparators, and small amplifiers that uses dual input voltage source specially  +12V, ground (0V), and -12V voltages.The circuit is based on the two complementary voltage regulators the 7812 (+12V) and 7912 (-12V). In building the circuit, check the polarity of the electrolytic capacitor to avoid problems.

dual 12V power supply

Materials:

1 - Transformer is 220VAC to 15V -0 -15V, 2A   or  (120V to 15V -0 -15V, 2A)
1 - bridge rectifier diode  rated 2A 
2 - 2200uF 25V electrolytic capacitor
2 - 220uF 16V electrolytic capacitor
1 - 7812 or any +12V regulator IC
1 - 7912 or any -12V regulator IC


Note: This power supply project is powered through  main supply and can cause electrocution.

16 Dual Variable Power supply Project by LM317 and LM337 regulator IC

This variable power supply project is made out from two complementary regulator IC, the positive LM317 regulator IC and negative LM337 regulator IC. This is a combination of variable power supply using LM317 and negative variable power supply using LM337. Unlike other dual power supply project that has a minimum voltage of plus and minus 1.2V to 1.5V, this power supply is designed that to have an output of 0V to 28V and 0V to -28 DC, which a great help specially when designing circuits that requires less than 1V.

Power supply operation

This power supply uses LM317 for the positive regulation that can supply an output of 0V to 28V dc at a maximum current of 1.5A (with heatsink or cooling fan). The output voltage of the positive regulator is given by the formula:
Vout = 1.25(1 + 5K/240) + (100uA) (5K) - 1.4V
Where,
240 is the resistance from adjust and output terminal of LM317
5K is the resistance of the potentiometer connected to adjust terminal
-1.4V is the forward voltage of the two diode connection

Similar to LM317 operation, LM337 control the negative regulation of output voltage to ensure its output to 0V to -28V of a maximum current of -1.5A (of course wit heatsink). The variable negative output is given by the formula:
Vout = -1.25(1 + 5K/240) – (100uA) (5K) + 1.4V
Where,
240 is the resistance from adjust and output terminal of LM337
5K is the resistance of the potentiometer connected to adjust terminal
1.4V is the forward voltage of the two diode connection

 
Power supply materials

D is 1N4001 diode or any of the same maximum current capacity. Fuse must be 0.5A, 250V or much lower amperage rating. Transformer is 220VAC to 26V -0 -26V, 2A  or 120V to 26V -0 – 26V rating of 60VA or higher, bridge diode must be rated 3A or higher for good circuit operation. The resistors used are rated 1/2W.The input capacitor must be  4700uF or larger for better regulation and stability. The output capacitor Cout is 10uF.



Note: This power supply project is powered through 220V main and can cause electrocution

0 Negative variable power supply using LM337 regulator IC

This variable power supply project uses LM337 regulator IC that can supply an output current up to 1.5A maximum at negative 28V.This simple LM337 power supply is the exact opposite pair of   positive regulator that uses lm317 IC. It is very useful in making or designing electronic projects that requires negative variable voltage inputs.

Power supply operation:
1. The transformer steps down the voltage from 220VAC to 26VAC per winding (52VAC in total)
2. The AC voltage is converted to DC by the rectifier diode
3. The DC voltage is filtered by the capacitor to eliminate voltage ripples
4. The LM317 regulates the output voltage and varies it from -1.25V to -30V through potentiometer

The transformer used in this power supply project is rated 220V to 28V with center tap and about 50VA. The diode D1 is 1N5401 or similar while diode D2 is 1N4001. The resistors used are rated 1/2W.The input capacitor (470uF in diagram) must be 3300uF or larger for better regulation and stability. The output capacitor Cout is 10uF.

Note: This power supply project is powered through 220V main and can cause electrocution

0 simple variable power supply project using LM317

variable power supply project

This variable power supply project  uses  LM317 regulator IC that can supply an output current up to 1.5A maximum at 28V.This simple power supply  is very useful in making or designing electronic projects that requires variable voltage inputs.
 
Power supply operation :
1.The transformer steps down the voltage from 220VAC to 26VAC per winding (52VAC in total)
2.The AC voltage is converted to  DC by the rectifier diode
3.The DC voltage is filtered by the capacitor to eliminate voltage ripples
4. The LM317 regulates the output voltage and varies it  from 1.25V to 30V  through potentiometer

The transformer used in this power supply project is rated 220V to 28V with center tap and about 50VA. The  diode D1 is 1N5401 or similar while diode D2 is 1N4001. The resistors used are rated 1/2W.The input capacitor (470uF in diagram)  must be 3300uF or larger for better regulation and stability.The output capacitor  Cout is  10uF.

Note : This power supply project is powered through 220V main and can cause electrocution