Variable DC Power Supply Circuit Diagram

This project provides the schematic & the parts list needed to construct a simple DC Power Supply from an input power supply of 7-20 V AC or 7-30V DC. This project will come in handy in case you use plenty of batteries for your basic electronics project.

Two DC voltage outputs are available; is a fixed regulated 5V for TTL use. The other output is variable from 5V upwards. The maximum output voltage depends on the input voltage. The specified maximum input DC voltage to the regulator is 35V. The maximum input voltage must be two volts higher than the regulated output voltage.

Variable DC Power Supply Circuit Diagram

The DC Power Supply circuit is based around the 7805 voltage regulator. Its only three connections input, output & ground & it provides a fixed output. The last digits of the part number specify the output voltage, e g. 05, 06, 08, ten, 12,15, 18, or 24. The 7800 series provides up to one amp load current & has on-chip circuitry to close down the regulator if any attempt is made to operate it outside its safe operating area.It can be seen that theres in fact separate circuits in this power supply. 7805 is directly connected as a fixed 5V regulator. The second 7805 has a resistor divider network on the output. A variable 500 ohm potentiometer is used to vary the output voltage from a maximum of 5V up to the maximum DC voltage depending on the input voltage. It will be about 2V below the input DC voltage.

The capacitor across the output improves transient response. The giant capacitor across the input is a filter capacitor to help smooth out ripple in the rectified AC voltage. The larger the filter capacitor the lower the ripple.

For tiny applications the heat sinks wont be needed. The tab on the regulator will dissipate 2W at 25 o C in air. (This is equivalent, for example, to an input voltage of 9V, an output of 5V & drawing 500 m A.) However, as your projects get bigger they will draw more current from the power supply and the regulators will operate at a higher temperature and a heat sink will be needed. You can basically add voltage & current meters to it and put it in to an appropriate plastic case connected to a transformer.

Trouble Shooting Procedure

An LED has been put in to the output of the fixed 5V regulator to indicate that the circuit is working. Poor soldering is the most likely reason that the circuit does not work. Check that all the soldering is done properly. Check that all parts are in their correct position on the PCB. Other items to check are to make sure that the regulators, electrolytic capacitor & bridge rectifier are inserted in the correct orientation.

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2N3055 The 25 30kV DC Generator

This High Voltage power supply is able to generate up to 25-30kV DC Output from a 12-24v DC input. With a fully adjustable DC input power supply (0-24V/4A), it is possible to adjust the HV output between 5 to 30kV. This HV power supply use a common flyback driver circuit with two 2N3055 power transistors as a push-pull oscillator. A common flyback transformer from an old TV/monitor can be used, the transformer HV output is connected to a 30kv Voltage tripler which commonly used in all color TV monitors.

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Suitable AC DC Circuit Diagram

This circuit is simple, but very useful as well as simple and inexpensive. Its use is simple, when the positive (red) is connected to a positive voltage DC and the black lead on the negative, the red LED lights. Reversing polarities the Green LED lights. Connecting the ends to an AC source both LEDs will light. The lamp current is limited to 40mA LEDs @ 220V AC and its filament is illuminated with approximately 30V, shining more intensely with increasing tension. Therefore, due to the behavior of the filament, any voltage in the range of 1.8 to 230 can be detected without changing component values​​.

Suitable AC DC Circuit Diagram

D1 = 3 mm or 5. red LED
D2 = 3 mm or 5. green LED
LP = 1220V 6W NEON

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DC Converter DC 12V to 24V Circuit Diagram

DC Converter - DC 12V to 24V Circuit Diagram. A voltage converter is very useful, if it raises the voltage from 12v to 24v. Can be used to power low power equipment and even a battery charger Notebook. It works with a two-transistor oscillator, type astable which drives a power transistor controlled by a Zener diode. Thus is achieved with a good efficiency and stabilize the output voltage of 24V.

The coil should be wound on a ferrite core in the form of 1 cm and consists of 100 turns of wire of 1 mm section.

DC Converter - DC 12V to 24V Circuit Diagram

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1 5 35 Volt DC Regulated Power Supply

Here is the circuit diagram of regulated power supply. It is a small power supply that provides a regulated voltage, adjustable between 1.5 and 35 volts at 1 ampere. This circuit is ready to use, you just need to add a suitable transformer. This circuit is thermal overload protected because the current limiter and thermal overload protection are included in the IC.

Picture of the circuit:

1A Regulated Power Supply Circuit Schematic

 

Circuit diagram:

1A Regulated Power Supply Circuit Diagram

 

Transformer selection chart:

Transformer selection Guide-Table For Power Supply

 

Parts:
IC = LM317
P1 = 4.7K
R1 = 120R
C1 = 100nF - 63V
C2 = 1uF - 35V
C3 = 10uF - 35V
C4 = 2200uF - 35V
D1-D4 = 1N4007

Features:

• Just add a suitable transformer (see table)
• Great to power your projects and save money on batteries
• Suitable as an adjustable power supply for experiments
• Control DC motors, low voltage light bulbs, …

Specs :

• Preset any voltage between 1.5 and 35V
• Very low ripple (80dB rejection)
• Short-circuit, thermal and overload protection
• Max input voltage : 28VAC or 40VDC
• Max dissipation : 15W (with heatsink)
• Dimensions : 52x52mm (2.1” x 2.1”)

Technical Specs

• Input Voltage = 40Vdc max Transformer
• Output Voltage = 1.5V to 35Vdc
• Output Current = 1.5 Amps max.
• Power Dissipation = 15W max (cooled)

Note:

• It has not to be cooled if used for small powers. 28 Volt AC max is allowed for the input voltage.

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TL594 12V DC Switch Mode Power Supply Circuit Diagram

Basic Of Switch Mode Power Supply

In recent years, the use of switch mode power supply (SMPS) has become more comon as more applications demand for greater power eficiency. It makes use of semiconductor (mostly MOSFET) fast switches to switch DC input that has been rectified at high frequency. The advantages of high frequency switching are that it reduces the size of inductor, capacitors & transformer used. Other advantages of switching power supply over linear power supply are :

1) High Efficiency (up to 90% and above for nice design).

2) Output can be higher than input.
3) Able to operate over a variety of input power supply.
4) Able to have over output.

The setback of using SMPS compared to linear power supply is that it generates electrical noise which contributes to electromagnetic compatibility design issues & more part count.

Buck Converter SMPS

The SMPS circuit below from Power Integration makes use of LNK304 as its high frequency switch. Take note that this circuit is non isolated type which means that the output is not electrically isolated from the input & all testing ought to be completed using an isolation transformer to provide the AC line input to the board.

Make positive that you have electrical safety knowledge & experience before you embark on doing this project.

12V DC Switch Mode Power Supply Circuit Diagram

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3 30V 3A Adjustable Regulated DC Power Supply circuit and explanation

This power supply is meant as an auxiliary or as a permanent power supply for all common circuits based on a stabilized DC voltage between 3 and 30V provided that the consumption does not exceed 3A. Of course this power supply unit can also be used for other purposes. Be replacing the trimmer by a potentiometer, it may even be used as an adjustable power supply unit. A good quality heatsink must be used.
[...]
Parts list:
R1 = 8.2K
R2 = 2.2K
R3 = 680R
R4 = 1K
R5 = 82K
R6 = 0.18R/5W
C1 = 470p
C2 = 100nF-63V
C3 = 100nF-63V
C4 = 100uF-63V
C5 = 10KuF-60V
D1-D6 = 6.6A
Q1 = MJ3001 (Darligton)
IC1 = UA723D

Specifications:
* Overload protected
* Sshort-circuit stable
* Output current: max. 3A
* Output ripple voltage: 0.5mV
* Output voltage: adjustable from 3 to 30V, stabilized
* Input voltage: 9 to 30V AC (depending on the desired output voltage)

Source: http://www.extremecircuits.net/2010/02/3-30v-3a-adjustable-regulated-dc-power.html

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Variable DC Power Supply LM317

Variable DC Power Supply LM317

This DC power supply circuit is adjustable using IC Voltage Regulator LM317. LM317 is a versatile and highly efficient 1.2-37V voltage regulator that can provide up to 1.5A of current with a large heat sink. Its ideal for just about any application. This was my first workbench power supply and I still use it.

Since LM317 is protected against short-circuit, no fuse is necessary. Thanks to automatic thermal shutdown, it will turn off if heating excessively. All in all, a very powerful (and affordable!) package, indeed.

Although voltage regulator LM317 is capable of delivering up to 37V, the DC power supply output circuit here is limited to 25V for the sake of safety and simplicity. Any higher output voltage would require additional components and a larger heat sink.

Make sure that the input voltage is at least a couple of Volts higher than the desired output. Its ok to use a trimpot if youre building a fixed-voltage supply.

Problems:
Follow all the safety precautions when working with mains voltage. Insulate all connections on the transformer.

Possible uses:
Variable workbench power supply, fixed-voltage supply. Just about any possible application when no more than 1.5A is necessary.

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12V to 30V DC to DC Converter circuit Diagram

 12V to +/- 30V DC to DC Converter circuit Diagram

This is a DC to DC converter for car power amplifier. 12V input generates +30V and -30V output for preamp or power amplifiers. Circuit uses SG3525 IC, Mosfets and switching power supply.

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50W DC DC Converters TRACOPOWER with the Highest Power Density

TRACOPOWER launches the high performance TEN50 Series with 12 models providing 50W power in a 1”x 2”x 0.4 “ compact package. Today already almost all of applications require a high efficiency of a voltage conversion. When we add to this requirement also saving of space and a galvanic isolation, we´ll get to widely used components – DC/DC modules. The TEN 50 Series models feature a very high efficiency of up to 92%. Excellent efficiency is maintained in over a wide load range and no minimum load is required for an accurate output regulation. They are available in three basic groups – TEN 50-12xx, TEN 50-24xx a TEN 50-48xx with a wide input voltage range (2:1).

 

Low thermal losses and the use of highest grade components allow an operating temperature range of –40°C to +85°C while up to 55°C no forced air cooling is required. With an optional heat-sink this temperature can even be increased. An operation without a forced air cooling is possible even at higher temperatures – at an adequate power derating ( 2%/K above 55°C and 2,5%/K above 65°C). The TEN 50 Series comes with remote On/Off function and have an adjustable output voltage (± 10%). Protection against overload and short-circuit, very compact dimensions and a 1500VDC isolation enable usage of TEN 50 modules in virtually any power application. [Link]

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12V DC to 220V 100W Inverter Circuit Diagram

12V DC to 220V 100W Inverter Circuit Diagram

This is 100W inverter circuit. It uses 4047 IC and IRF540 Mosfet instead of 2N3055 transistor. Power output is 100W from 2-3A transformer.

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LTM4620 – Dual 13A or Single 26A DC DC µModule Regulator with Integrated Heatsink

The LTM4620 is a dual 13A per output (or single 26A output) DC/DC μModule step-down regulator that delivers up to 100A when four devices are current shared. The LTM4620 is a complete DC/DC regulator system in a 15mm x 15mm x 4.41mm LGA package, including inductors, power stages and all control circuits. For optimum heat dissipation, an integrated top side heat sink removes heat quickly and evenly.[Link]

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