1.3-12V Small Variable Power Supply

This is a small variable power supply delivers adjustable output voltage of 1.3v-12v. The current output determined by R3. With current setting (see part list), it will deliver current output about 1A.

6-8A / 0-28V Variable Power Supply Circuit

This is the schematic diagram of variable power supply. The output voltage of this power supply circuit can be adjust from 0V to 28V DC, while the current output is static the rang is about 6A up to 8A.

Parts List:

R1 = 2K2 Ohm 2,5 Watt R2 = 240 Ohm R3,R4 = 0.1 Ohm 10 Watt R7 = 6K8 Ohm R8 = 10K Ohm R9 = 47 Ohm 0.5 Watt R10 = 8K2 Ohm C1, C7, C9 = 47nF C2 = 4700uF/50v – 6800uF/50v C3, C5 = 10uF/50v C4, C6 = 100nF C8 = 330uF/50v C10 = 1uF/16v C11 = 22nF

D1…D4 = four MR750 diodes (MR750 = 6 Ampere diode) or 2 x 4 1N5401 diodes. D5 = 1N4148, 1N4448, 1N4151 D6 = 1N4001 D10 = 1N5401 D11 = LED D7, D8, D9 = 1N4001 TR = 2 x 15 volt (30volt total) 6+- Ampere IC1 = LM317 T1, T2 = 2N3055 P1 = 5k P2 = 47 Ohm or 220 Ohm 1 Watt P3 = 10k trimmer pot F1 = 1 Amp F2 = 10 amp

Source: circuitdiagram.net

Offline Switching Power Supply Circuit (5V - 10A - 50W)

Here the schematic diagram of offline switching power supply:

Circuit Diagram:

Parts List:

This switching power supply is using a MOSFET. For 220V AC voltage input, use BUZ80A/IXTP4N8 MOSFET and for 110V AC input voltage, use GE IRF823 MOSFET. The output will be 5 Volt DC with electric current can be reach 10A.

Positive Variable Power Supply circuit

The following diagram is the schematic diagram of positive adjustable/variable power supply. It means that the power supply output will be DC current with positive [+] and ground [0] polarity.

Schematic diagram:

Power Supply Input:

Component part list:
R1 = 330
R2 = 1K
VR1 = 10K 10-turn trimpot
C1 = 2200uF/50V
C2,4 = 100nF ceramic
C3,4 = 10uF/63V
D1-6 = 1N5403
REG IC = LM317T
Heatsink

Visit this page to download the variable power supply diagram manual.

Low-Ripple Power Supply

This circuit can be used where a high current is required with a low-ripple voltage (such as in a high-powered class AB amplifier when high-quality reproduction is necessary). Q1, Q1 and R2 can be regarded as a power Darlington transistor. ZD1 and R1 provide a reference voltage at the base of Q1. ZD1 should be chosen thus: ZD1=Vout-1.2 . C2 can be chosen for the degree of smoothness as its value is effectively multiplied by the combined gains of Q1/Q2, if 100uF is chosen for C2, assuming minimum hfe for Q1 and Q2, C=100x15(Q1)x25(Q2)=37,000uF.

Variable Power Supply with L200

This is adjustable power supply schematic diagram with IC L200 for its power regulation.

Voltage output is controlled by 10K variable resistor. Output voltage range value will be about 3 to 15 volts, and current range is about 10mA minimum and 2 amp maximum. Reaching the current limit will reduce the output voltage to zero.

3-30 V/2.5 A Adjustable Stabilized Power Supply

This is Simple 3-30 volt adjustable and stabilized power supply circuit. You can use this circuit for general purpose.

Here the schematic diagram:

Component list:

R1 = 560R 1/4W	C1 = 100nF
R2 = 1,2 K 1/4W	C2 = 2200uF 35-40V
R3 = 3,9 K 1/4W	C3 = 100 pF
R4 = 15K 1/4W	C4 = 100uF/ 35V
R5 = 0,15R 5W
D = B40 C3300/2200, 3A rectifier bridge
P1 = 10K potesiometer	TR1 = BD 135
IC = LM723	TR2 = 2N3055

PCB layout:

Components placement:

For complete explanation, circuit's works and how to build this circuit into the box, download the full tutorial here

Dual Regulated Power Supply

This is dual regulated power supply. There are 3 output that are (+) voltage, (0) Grounding, and (-) voltage. The current output max about 0.3-0.5 A.

You need center tap transformer. for example, if you need 12v output, you should connect J1 to 15v transformer output, J2 connected to 0v and J3 connected to another 15V.

Electronic Fuse for DC Short Circuit Protection

This circuit will protect your power supply or battery. The electric current will stopped by relay when electric current short occured, Relays must be chosen with a voltage value equals to the input voltage. Don't omit using the 100uF capacitor with appropriate voltage value with respect to the input voltage. If you can't provide, you can use C106 instead of BRX46.

You can adjust the current with using 10K potentiometer. If you will use the fuse with very high currents, lower the 0R6 5W resistor value (ex. 0R47, 0R33, 0R22 or 0R1). Watt value of the resistor should be increased also.

Power Supply 1.3 - 32 V / 5A with Short Circuit Protection

This is a very easy to build power supply that is based on LM338 5A adjustable voltage regulator. I am using the supply for a long time, have no problem yet. Only current adjust is missing but I overcome this situation by using an LCD panel ampermeter. There is no PCB for the circuit. I took a 3x16 copper plate and strip the unused areas by a knife. If you want you can use analog meters instead of LCD panels.

Notes:

1. Use thick wires for connections.
2. When connecting the LM338 to the heatsink use thermal paste.
3. Use external supplies for LCD panels. They can be 9V batteries. The panels I use draws 1mA current and the batteries last sufficiently long time. If you have small transformers which can supply regulated 9V, you can use them. You need separate transformers for each panel!
4. The transformer should be 100 Watt but if you don't need high current you can try transformers that you already have. (I can draw 6A from 100Watt transformer.)
5. If you have multi winding transformer you can use the diode connections shown in schematic. Diodes must be 10-15 A.
6. Be careful while connecting LM338. Don't put it inverse.
7. Output of your transformer mustn't exceed 25V AC...

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Power Supply 1.2 - 12V / 1A with low voltage LED Indicator

This power supply can provide output voltage 1.2V - 12 with maximal output current is 1A, low voltage LED indicator added in this schematic diagram. The indicator part includes three diodes and one LED. For example you are charging a battery, you can observe the charge status at that moment. Another advantage of this circuit, when the drawn current exceeds 1A (practically 0.85A), the current protector in LM317 intervenes and LED indicator warns you about the very low output voltage.

0 to 3V Adjustable Output Power Supply

This is an LM317 based adjustable voltage regulator with a maximum output of 3V and 1.5A. The output voltage depends on the V_IN, R1 and R2 values, so the circuit can be modified to use with a maximum output of greater than 3V. The maximum current output is also independent of the circuit design, it is related to the package options. In this circuit, LM317T, which is capable of transferring up to 1.5A, is used.

Since the internal reference voltage of the LM317 regulator is 1.25V, the output voltage can be also minimally 1.25V. One way to overcome this problem is using a reference voltage source built on two diodes. But this approach is mostly suitable for 1.5V to 15V regulators since the sensitivity becomes poor for the low voltage outputs less than 1.5 . On the other hand, diodes have temperature dependent forward voltages.

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General Purpose Power Supply

General purpose power supply schematics:

You can select the output voltage range by 0-30V or 0-40V of 0-60V. The component's value will be different depends the output range you choose.

Vout	Iout	R1	R4, R5	R9	Tr1	C1/C5	IC1	Tr2	Tr3
0-30V	1.3A	0.47Ohm	33k	2k7	24V/2A	40V	723	BD242	2N3035
0-40V	0.8A	0.82Ohm	47k	5k6	33V/1.5A	63V	L146	BD242A	2N3035
0-60V	0.6A	1.2Ohm	68k	19k	48V/1A	80V	L146	BD242B	2N3442

Please check the output current since higher voltage output will decrease the current output.

12Volt to 9Volt DC Converter

Parts List:
R1 = 560 ohm
C1 = 1000uF/40V, Electrolytic
C2 = 10uF/25V, Electrolytic
C3 = 330nF, Ceramic
Z1 = 9.1V, 1watt zener
Q1 = ECG184, NTE184

Notes:
To get a more precise output voltage, replace zener diode Z1 with 10V and R1 with a 1Kilo ohm potentiometer. A Coolrib for Q1 is optional but highly recommended. You can replace Q1 for a more robust type to get more output amps depending on your requirements. Simple circuit to power your 9 volt cassette recorder and other stuff.

http://www.uoguelph.ca/~antoon/circ/car912.htm

Battery 9V Voltage Doubler

MAX1044 is a charge pump converter - it uses a capacitor as a "bucket" to pump charge from one place to another. Normally, there is a capacitor connected from pin 2 of the 1044 to pin 4. This capacitor is charged between +9V and ground, and then switched in parallel with a capacitor from pin 5 to ground in a way that makes a negative voltage on the second cap.

In this UPverting use, the 1044 still switches pin 2 between +9V and ground just as it would for a voltage inverter. However, we ignore the pin 4 and 5 connections that would make an inverter from it. Instead, we connect two capacitors and diodes as shown (D1, 2, and C1, 2). The voltage on pin 2 of the 1044 is switched from +9V to ground. When it switches to ground, C1 fills with voltage through D1. When it then switches to +9, it pulls the negative terminal of C1 up to +9V. D1 now blocks any flow of current back into the battery, so the charge in C1 flows through D2 into C2. So at C2, we now get almost 18V!

There's more. If we add another two diodes and capacitors (D3, D4 and C3, C4), we can add another 9V to it, as C3 charges to +18 through D3 when pin 2 is at ground, and is pulled up to +25 (+27 minus the voltage drops of the diodes) when pin 2 goes high. We can do it again with D5, D6 and C5, C6 to get +33V. The limit on all this is the losses in the diode voltages. Each time we add a section, we add two more diode drops that we can't take advantage of to charge capacitors. But +33 is not bad for a single 9V battery!

If you build this, you MUST take notice of the voltages on the capacitors. The caps can all be the same value, but C1, C2 need to be 25V units, C3, 4, 5, and 6 can be 35V units, and C5 and C6 might need to be 50V unit just for some safety margin. 1N400x diodes work and are cheap, but the losses are higher than they really need to be. For higher performance and lower losses, it's better to use something like the 1N5817 schottky diodes for low losses. But both will work.

This charge pumping is a very efficient way to convert voltages. The only power lost is that power dissipated in the resistances of the switches inside the 1044 and the series resistance of the capacitors and diodes, as well as the power to run the internal oscillator that flips the switches when needed.

All by itself, the 1044 runs at about 7-10kHz, so there will be ripple of that amount on the C2 output and on the +9V output from the battery as well. Audio equipment that uses this voltage could have a "whine" audible if you're not careful. However, the 1044 has a frequency boost feature. If you connect pin 1 to the power supply (shown by the little open switch) then the oscillator frequency goes up by about 6:1. The oscillator then works well above the audio region. Any whine is then going to be inaudible.

Unregulated Power Supply

This page come from ww.zen22142.zen.co.uk, show you about circuit of un regulated powersupply:

A basic full wave rectified power supply is shown below. The transformer is chosen according to the desired load. For example, if the load requires 12V at 1amp current, then a 12V, 1 amp rated transformer would do. However, when designing power supplies or most electronic circuits, you should always plan for a worst case scenario. With this in mind, for a load current of 1 amp a wise choice would be a transformer with a secondary current rating of 1.5 amp or even 2 amps. Allowing for a load of 50% higher than the needed value is a good rule of thumb. The primary winding is always matched to the value of the local electricity supply.

Notes:
An approximate formula for determining the amount of ripple on an unregulated supply is:

Vrip = Iload * 0.007 / C

where I load is the DC current measured through the load in amps and C is the value of the capacitor in uF.The diagram below shows an example with a load current of 0.1 amp and a smoothing capacitor value of 1000uF.

The calculated value of ripple is (0.1 * 0.007) / 1000e-6 = 0.7 volts or 700mV. The value of peak-peak ripple measured from the graph is 628mV. Therefor, the equation is a good rule of thumb guide for choosing the correct value for a smoothing capacitor in a power supply.