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Variable DC Power Supply 3-24V / 3A

This is the variable DC power supply circuit. This power supply has regulated output, can be adjusted from 3 to 25 volts and the current output is limited to 2 amps as shown, however it may possibly be improved up to 3 amps or more by applying a smaller current sense resistor (0.3 ohm). Voltage regulation is controlled by 1/2 of a 1558 or 1458 op-amp. The 1458 may be substituted in the circuit, but it is suggested the supply voltage to pin 8 be limited to 30 VDC, which can be achieved by adding a 6.2 volt zener or 5.1 K resistor in series with pin 8. The 2N3055 and 2N3053 transistors need to be attached on proper heatsinks and the current sense resistor must be rated at 3 watts minimum.

600V Power Supply for QRO HF Amplifiers

Here the schematic design diagram of 600V power supply for QRO HF amplifiers. Amateur Radio Transmitters working with valves such as 807 or1625 operates properly using a plate voltage in between 600V to 700 Volts. The circuit described below is actually a full wave voltage doubler. The output voltage is twice the input voltage. For 230V AC input the output is going to be close to 600 Volts.


Resister R1 is applied to minimize the initial high voltage and high currents. Capacitor C1, C2, C3 along with coils L1 and L2 form input line filter. The capacitors C4 and C5 protects diodes from high voltage transients on the AC line as well as minimizes inter carrier hum modulation of the R.F picked up by the mains. Capacitors C6 and C7 gives sufficient filtering for the output DC Voltage.

DC Short Circuit Protection with Electronic Fuse

Here the diagram of electronic fuse circuit. This circuit will help to protect the load against short circuit for DC circuit application. Relays should be chosen with a voltage value equals to the input voltage. Do not omit making use of the 100uF capacitor with proper voltage value with respect to the input voltage. The circuit use Silicon Controlled Rectifier (SCR) BRX46 which is designed for control systems and sensing circuit applications. In case you cannot find this component, it is possible to use C106 as a substitute of BRX46.

Discharge Indicator Circuit for 12V Lead Acid Battery

Here the discharge indicator circuit for Lead Acid battery 12V. This circuit is used to prevent the batteries from damage. When discharging the battery voltage pin 12V Lead may not be reduced below 10.8V, so we notice the lighting of Led, when the voltage falls below this value. To achieve control we need a constant voltage and a circuit that can compare this with the controlled voltage. And these two conditions to ensure the IC1-LM 723.

Split Power Supply Circuit 22V DC

This is the circuit diagram of split power supply circuit which will give a regulated DC voltage (+)22V ; GND and (-)22V. This is an old regulated power supply design which built using active components of dioda zeners and transistors to give regulated output.

This is a very basic voltage regulator circuit, without any additional features such as foldback current limiting, and doesn't have the same performance as an IC regulator such as 78xx series.

Variable Lab Power Supply 0-24V / 4A

Variable lab power supply 0-24V / 4A, it is a laboratory power supply with output voltage continuously adjustable from 0 V to 24 V DC, remote voltage sense capability (Sense internal/external). It has output current limit which is continuously adjustable from 0.04 A to 4 A and output current which can be limited continuously or output shut down (Limit/cut).

Remote sensing means that there are actually two extra wires which sense the delivered voltage at the load and compensate for any voltage drop along the cables which carry the delivered electric current. This improves voltage regulation at the load significantly but needs two extra wires for the sensing. A switch will allow internal sensing at the output terminals for easier operation when remote sensing isn't necessary.

Read the detailed explanation about Variable Lab Power Supply 0-24V / 4A

Variable Power Supply Circuit 3-24V / 2A

This the variable power supply with regulated output. The circuit can be altered from 3V to 25V and the electric current is limited to 2 amps as shown. But it's possible to be increased to 3 amps or more by applying a smaller current sense resistor (0.3 ohm).

The power transistor 2N3055 and 2N3053 is used to boost the output current and it should be mounted on suitable heat sinks and the current sense resistor should be rated at 3 watts or more.

2000V High Voltage Low Current Power Supply

This is a high voltage, low current power supply circuit which will give you high power voltage about 2000V output from 15VDC input.

A high voltage power supply can be a really beneficial source which could be properly utilized in a lot of applications like biasing of gas-discharge tubes and radiation detectors and so on. Such a power supply could also be utilized for protection of property by electric charging of fences. Here the electric current requirement is of the order of several microamps. In such an application, high voltage would basically exist in between a ‘live’ wire and ground. When this ‘live’ wire is touched, the discharge starts through body resistance and it provides a non-lethal but deterrent shock to an intruder. The circuit is built around a single transistorised blocking oscillator. An vital element in this circuit could be the transformer. It could be fabricated on quite easily available ferrite cores. Two ‘E’ sections of the core are joined face-to-face after the…

15V Switching Power Supply Circuit

Switching power supply circuit, give you 15V DC output with 1A electric current. It will be 15 watt power output. Looks like this circuit come from Rusia, some components type might not available in your location, you should find the substitude of component parts first.

Source: Switching power supply 15 Watt

LT1086 Negative Voltage Regulator

This is the efficient negative voltage regulator circuit built based IC LT1086.

One way to provide good negative-voltage regulation is with a low-dropout positive-voltage regulator operating from a well-isolated secondary winding of switch-mode circuit transformer. The technique works with any positive-voltage regulator, although highest efficiency occurs with low-dropout types.

Under all loading conditions, the minimum voltage difference between the regulator VIN and V0UT pins must be at least 1.5V, the LT1086's low-dropout voltage. If this requirement isn't met, the output falls out of regulation. Two programming resistors, R1 and R2, set the output voltage to 12 V, and the LT1086's servo the voltage between the output and its adjusting (ADJ) terminals to 1.25 V. Capacitor C1 improves ripple rejection, and protection diode D1 eliminates common-load problems.

Since a secondary winding is galvanically isolated, a regulator's 12 V output can be referenced to ground. Theref…

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

The following diagram is the circuit diagram of offline switching power supply circuit:

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 Regulator Circuit with PNP and NPN Transistor Boost

Here the schematic diagram of positive regulator with PNP and NPN transistor boost. Inside the circuit, Q1 and Q2 are wired in the classic SCR or thyristor configuration. In which higher input voltages or minimum element count are needed, the circuit for thyristor boost could be applied. The thyristor is working in a linear mode with its cathode as the control terminal and its gate to be the output terminal. This is known to be the remote base configuration.

5V to Isolated 5V Converter Circuit

This is the circuit diagram of 5V to Isolated 5V Converter, rated at 20mA electric current.

In this converter circuit, a negative output voltage dc to dc converter generates a -5V output at pin A. In order to generate -5V at point A. the primary of the transformer must fly back to a diode drop more negative than -5V. If the transformer has a tightly coupled I : 1 turns ratio. there will be a 5 V plus a diode drop across the secondary. The IN5817 rectifies this secondary voltage to generate an isolated 5V output. The isolated output is not fully regulated since only the -5V at point A is sensed by the MAX635.

5V Regulated Power Supply Circuit with Over Voltage Protection

The 5V regulated power supply for TTL and 74LS series integrated circuits, has to be really precise and tolerant of voltage transients. These IC's are effortlessly damaged by short voltage spikes. A fuse will blow when its electric current rating is exceeded, but demands several hundred milliseconds to respond. This circuit will react in several microseconds, triggered when the output voltage exceeds the limit of the zener diode.

This circuit uses the crowbar method, where a thyristor is employed and short circuits the supply, causing the fuse to blow. This will take position in a few microseconds or less, and so provides considerably higher protection than an ordinary fuse. If the output voltage exceed 5.6Volt, then the zener diode will conduct, switching on the thyristor (all in some microseconds), the output voltage is therefore reduced to 0 volts and sensitive logic IC's will probably be saved. The fuse will nonetheless take just a few hundred milliseconds to blow but this…

Voltage Regulator with FET KP103K

This is a voltage regulator circuit built based FET KP103K. The FET VT3 acts as a dynamic load for the transistor VT2. Because of this factor increases the voltage regulation: when the input voltage from 11 to 19 V output voltage varies within ± 60 mV. Rated output voltage using Zener type D814B is 9 V.

Voltage Regulator with FET KP103K circuit source: Voltage Regulator with FET

1.5V-25V DC Variable Power Supply

This is 1.5V-25V DC Variable Power Supply. The power supply use KR142EN14 or LM317 as regulator component. KR142EN14 or LM317 is capable to handle electric current up to 2A. You may use LT1083/84/85 to handle electric current of 7A/5A/3A. Resistor R9 is used as a current sensor to an ammeter.



Components list:
R1 : 4K3
R2 : 18K
R3 : 100
R4,R8 : 100K
R5 : 1K
R6 : 240
R7 : 4K7 ( Variable resistor )
R9 : 0.33 E
C2 : 0.1uF
C3 : 10000uF/40VC4 : 100uF/25V
D1 : KY202
D2 : KD521
D3 : D311
D4 : KC147
T1 : KT814B
T3 : KT209
T4 : KT3102
IC1 : KR142EN14 (LM317)

Circuit source: 1.5V-25V power supply with preregulator

LT1070 Boost Converter Circuit, 5VDC to 12VDC

This is a converter circuit which will convert 5VDC input to become 12VDC output. The circuit is based LT1070 which also will boost the current output.

About LT1070:
The LT®1070/LT1071 are monolithic high power switching regulators. They can be operated in all standard switching configurations including buck, boost, flyback, forward,inverting and “Cuk”. A high current, high efficiency switch is included on the die along with all oscillator, control and protection circuitry.Boost Converter circuit reference, download: LT1070 datasheet

Cheap Low-Dropout 12V / 3A Linear Regulator

The following diagram is the cheap Low-Dropout linear regulator circuit.




This linear post regulator circuit provides 12 V at 3 A. It applies TL431 reference U1 which, without additional amplification, drives TMOS MTP3055A gate Q1 series pass regulator. Bias voltage is applied through R1 to Q1's gate, which is protected against overvoltage by diode CR1. Frequency compensation for closed-loop stability is provided by C1.

Circuit Characteristics:
Dropout voltage: 0.6 V
Line regulation: ±5 mV
Load regulation: 10 mV
Output ripple: 10 mV pk-pk

NiCd NiMH Battery Charger using PIC16C711

This is the battery chargercircuit for NiCd and NiMH battery tipe. The circuit is using microcontroller PIC16C711 for constant current supply. A constant current supply is switched on and off as required by a micro-controller. The microcontroller senses the battery voltage and internally uses an analog to digital converter to read the battery voltage. The microcontroller, requires its own 5V regulated supply and displays the current charging status on two LEDs. The smallest and cheapest micro-controller that could be used to perform the Analog to Digital function and still have the necessary functions and control lines to do this is the PIC16C711.

Visit this page for full explanation about this NiCd NiMH Battery Charger circuit

Tracking Preregulator circuit

The following diagram is the schematic diagram of tracking preregulator circuit uses LM308, LM360, 2N2905.

15A DC Voltage Regulator

The following circuit diagram is a 15A DC voltage regulator based LM338

Electronic Power Controller Circuit

This is an electric power controller which implemented the bidirectional triode thyristor(TRIAC). This circuit can manage the electrical power using the a single variable resistor.

This circuit is applied for the dimmer which adjusts the light from the bulb. This circuit adjusts the quantity of the electrical current which flows via the load together with the bidirectional triode thyristor and controls the electric power. It truly is only the alternating voltage that may be controlled with this circuit and it is impossible to perform the control in the DC voltage.

Simply because it controls the passing time in the alternating current by the bidirectional triode thyristor, the electrical current which flows via the load is not the clean sine wave type. Due to the fact it's, there is limitation in the equipment which may be controlled with this circuit. The bidirectional triode thyristor is usually called by the trade name TRIAC.

The equipment which can be controlled
The equipment whic…

Voltage Double Circuit with timer IC 555

This is a voltage double circuit which build using well-known timer IC 555. The circuit is very simple, and is easily to build. Construction is not crucial.

Here the schematic diagram:



Rectifier diodes should be ultrafast (UF4004 or similar), or you can use 1N4148 signal diodes. Losses will be slightly higher if you use signal diodes, or lower if you wanted to go to the trouble of using Schottky diodes - the latter are not warranted in such a simple circuit (IMO). The zener diode is to protect the circuit against transient overvoltage, and is optional.

Voltage Double Circuit with timer IC 555
source: http://sound.westhost.com/project95.htm

Current Output Doubler after 78xx Regulator

This is about how to increase the current output limit after voltage regulating process using regulator 78xx series. As we know, current output after 78xx regulator is about 1 - 1.5A. With this circuit, you will be able to get higher current output from regulated power supply.


Components List:
R1, R2 = 4.7 K
C1, C2 = 4700 uF / 16V
C3 = 47,000 uF / 35V
D1,D2, D3 = 1N5401 ( 3 Amp Diodes )
D4 & D5 – Light Emitting Diodes (LED)**
IC1, IC2 – 78xx series regulator IC ( 7805 for 5V, 7812 for 12V etc.)

Visit this page for detailed instruction and explanation how to doubling the current output after regulate the voltage with IC regulator 78xx series.

Voltage Doubler Circuit: 12VDC to 18VDC or 24VDC

Here the schematic diagram voltage converter circuit: 12VDC to 18VDC or 24VDC:


This voltage doubler circuit will convert 12-V power supply to become a 24VDC and 18VDC. Use this circuit with almost any PNP or NPN power transistor.


Component Parts list:
U1: NE 555 timer.
C1 and C2: 50μF/25V
Q1: TIP 29, TIP120, 2N4922, TIP61, TIP110, or 2N4921.
Q2: TIP30, TIP125, 2N4919, TIP62, TIP115, or 2N4918.

3A Switching Regulator Circuit

Here the simple and cheap switching regulator circuit which capable to deliver 3A electric current.



Use the heatsink on the transistor to prevent damage due to overheating on its.

UPS Circuit for Cordless Telephone

This is the schematic diagram of UPS CIrcuit for Cordless Telephone:


When the AC mains is present, the very same is converted into DC and fed to the inverter. A component of the mains rectified output is being used to charge the battery. When the mains power fails, the DC supply to the inverter is from the battery and from this is obtained AC at the inverter output.

The circuit wired around IC CD4047 is an astable multivibrator operating at a frequency of 50 Hz. The Q and Q outputs of this multivibrator directly drive power MOSFETS IRF540. The configuration applied is push-pull type. The inverter output is filtered as well as the spikes are reduced working with MOV (metal oxide varistor). The inverter transformer chosen is an ordinary 9V-0-9V, 1.5A mains transformer readily offered inside the market. Two LEDS (D6 and D7) indicate the presence of mains/battery.

The mains supply (when present) is stepped down, rectified and filtered working with diodes D1 via D4 and capacitor C1. A compone…

Dual Polarity Power Supply +33V, 0 , -33V

The following diagram is the example of dual polarity power supply circuit which will give you (+33V) ; (0) and (-33V) DC voltage. This circuit is usually used for power amplifier circuit which require dual polarity power supply to work.



Components List:
R1 = 3K3 1/2W
C1 = 10nF/1000V
C2,C3 = 4700µF/50V
C4,C5 = 100nF/63V
D1 = 200V 8A Diode bridge
D2 = 5mm. Red LED
F1,F2 = 3.15A Fuses with sockets
T1 = 220V Primary, 25 + 25V Secondary, 2A minimum
PL1 = Male Mains plug
SW1 = SPST Mains switch

source: redcircuits.com

Unregulated Dual Polarity Power Supply

This is the schematic diagram of Unregulated Dual Polarity power supply.


Unlike 78xx and 79xx dual polarity regulated power sypply and LM317/LM337 dual polarity regulated power supply which have limited current output and voltage (have limited supply power), this unregulated power supply will give you more power.

This kind of circuit usually used for power amplifier which need high supply power, or as high current lead acid battery charger (single polarity only).

The component value is flexible refer to your needs. For example: if you need power supply for 100W amplifier, then the component value are:
Transformer: 3A minimum (center tap)
Diodes: 3A diode (1N5401, 1N5402, 1N5403 etc)Electrolytic capacitor: 4x minimum of 4700uF/50V (the higher is better - check the capacitor voltage, change it for higher voltage. example: use 63V capacitors for 45V power supply output.)

5V DC / 10A Offline Switching Power Supply

Offline switching power supply which resulting 5VDC/10A output from 110/220V AC home power electric. See the parts list, there should be different MOSFET type for 110V anf 220V volatage input.

Below the diagram:




And here the parts list:


The schematic shows a 50-W power supply with a 5-V 10-A output. It is a flyback converter operating inside the continuous mode. The circuit has functionality of a main side and secondary side controller will full-protection from fault conditions such as overcurrent. When the fault condition has been removed, the power supply will go into the soft-start cycle just before recommencing normal operation.

Positive Voltage Regulator Circuit with PNP Boost

The IC8211 presents the voltage reference and regulator amplifier, although Q1 will probably be the series pass transistor. R1 defines the output current of the IC8211, although C1 and C2 present loop stability and as well act to suppress feedthrough of input transients to the output supply. R2 and R3 define the output voltage as follows:



Furthermore, the values of R2 and R3 are preferred to create a bit volume of standing current in Q1, which provides additional stability margin on the circuit.Where accurate setting of the output voltage is needed, either R2 or R3 could possibly be designed adjustable. If R2 is designed become adjustable,then the output voltage will vary linearly with the shaft angle; nevertheless, if the potentiometer wiper was to open the circuit, the output voltage would rise. Normally, for that reason, it is far more beneficial to provide R3 adjustable, due to the fact this can give fail-safe operation.

Low Forward-Drop Power Supply Circuit

Check out the signal output... this power supply will cut off the negative amplitudo and pass the positive AC signal.

A TMOS power FET , Q1 , and LM393 comparator supply a higher performance rectifier circuit. When VA exceeds VB, U1's output turns into higher and Q1 conducts. Conversely, when VB exceeds VA, the comparator output gets low and Q1 does not conduct.

The forward drop is determined by Q1's on resistance and latest I. The MTH40N05 has an on resistance of 0.028 Ohm; for I = 10 A, the forward drop is much less than 0.3 V. Typically, the very best Schottky diodes usually do not even start conducting below several hundred mV.

9V Stabilized Power Supply Circuit with LM723

Here the 9V Stabilized power supply circuit. Built based IC 723 and featured with amp booster using 2N3055. The 2N3055 must be mounted on a coolrib/heatsink.

Schematic Diagram:



Components List:

R1 = 0.56 Ohm, 1 Watt, wire-wound type, 5%
R2 = 750 Ohm, 5%
R3 = 2K7 (2700 ohm)
P1 = potentiometer, 1K, Linear
C1 = 2200uF, 35V
C2 = 470pF
T1 = 115/10 VAC transformer. Center Tap (ct) not needed.
IC1 = uA723, LM723, or equivalent.
Q1 = 2N3055, NTE130, or substitute. (TO-3 case) Mount on a coolrib!
BR1 = 80V-5A (or better)

Circuit Notes:
C1 filters the noise and spikes off the AC. Adjust the circuit for 9V or 12V output voltage, or whatever voltage level your pc mini drill is using, with the P1 potentiometer.Q1 can also be a MJ2955 in a TO-3 case.

Design by Tony van Roon
Source: http://www.sentex.ca/~mec1995/circ/9vstable.htm

24V Lead-Acid Battery Charger Diagram

This circuit is a current limited lead acid battery charger built around the famous variable voltage regulator IC LM 317. The charging current depends on the value of resistor R2 and here it is set to be 700mA. Resistor R3 and POT R4 determines the charging voltage. Transformer T1 steps down the mains voltage and bridge D1 does the job of rectification. C1 is the filter capacitor. Diode D1 prevents the reverse flow of current from the battery when charger is switched OFF or when mains power is not available.

The schematic diagram:

Circuit Notes:Assemble the circuit on a good quality PCB.F1 can be a 2A fuse.T1 can be a 230V primary, 35V/3A secondary step down transformer.LM317 must be fitted with a heat sink.If 3A Bridge is not available, make one using four 1N5003 diodes.R2 = 0.85 ohm is not a standard value. You can obtain it by combining a 6.2 ohm and 1 ohm resistors in parallel.To setup the charging voltage, power ON the charger and hook up a voltmeter across the output terminals …

DC Battery Tester circuit

This is a DC battery tester circuit diagram. The circuit will work for DC battery from 1.5V up to 9V.Electronic Parts List:
R1 = 18K Ohm
R2 = 240 Ohm
R3 = 8.2K Ohm
R4 = 3K Ohm
R5 = 10 Ohm
M1 = Panel Meter (Any Panel Meter will work)Source: dc battery tester

NiCad Battery Charger

Simple NiCad battery charger with current and voltage limiting features. This circuit should be very easy to built.


Circuit source: NiCad Battery Charger

NiCad Battery Chargercircuit

0-28V / 6A Regulated Variable Power Supply

Parts list:

TR = 2 x 15 volt (30volt total) 6+- amps
D1...D4 = four MR750 (MR7510) diodes (MR750 = 6 Ampere diode) or 2 x 4 1N5401 (1N5408) diodes.
F1 = 1 Amp
F2 = 10 amp
R1 = 2k2 2,5 Watt
R2 = 240 ohm
R3,R4 = 0.1 ohm 10 watt
R7 = 6k8 ohm
R8 = 10k ohm
R9 = 47 0.5 watt
R10 = 8k2
C1,C7,C9 = 47nF
C11 = 22nF
C2 = 4700uF/50v - 6800uF/50v
C3,C5 = 10uF/50v
C4,C6 = 100nF
C8 = 330uF/50v
C10 = 1uF/16v
D5 = 1N4148, 1N4448, 1N4151
D6 = 1N4001
D10 = 1N5401
D11 = LED
D7, D8, D9 = 1N4001
IC1 = LM317
T1, T2 = 2N3055
P1 = 5k
P2 = 47 Ohm or 220 Ohm 1 watt
P3 = 10k trimmer

This is definitely an simple to create power supply which has reliable, clear and regulator 0 to 28 Volt 6/8 Ampere output voltage. By using two 2N3055 transistor, you'll get two times the amount of electric current.

Although the 7815 power regulator is going to kick in on brief circuit, overload and thermal overheating, the fuses within the primary …

Lead Acid Battery Charger Schematic

This circuit gives an initial voltage of 2.5 V per cell at 25℃ to rapidly charge the battery. The charging current decreases as the battery is charging, and when the current drops to 180 mA, the charging circuit reduces the output voltage of 2.35 V per cell, leaving the battery in a fully charged state. This lower voltage prevents the battery from overcharging, which would shorten its life.

The LM301A compares the voltage drop across R1 with an 18 mV reference set by R2. The comparator’s output controls the voltage regulator, forcing it to produce the lower float voltage when the battery-charging current, passing through R1, drops below 180 mA. The 150 mV difference in between the charge and float voltages is certainly set by the ratio of R3 to R4. The LEDs present the state of the circuit.

Temperature compensation assists stop overcharging, especially when a battery goes through wide temperature changes whilst becoming charged. The LM334 temperature sensor ought to be placed near or on…