Variable Power Supply Using LM723

Using LM723 regulator can be designed a very simple variable power supply circuit which can provide a maximum current up to 2A and a variable voltage between 2 and 25 volts.This 25v variable power supply is designed using a LM723 regulator and a few common electronic components.Input voltage must be between 28 and 37 volts. Mj3000 transistor must be mounted on a radiator for heat dissipation.

LM723 Variable Power Supply Circuit diagram

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High Current Power Supply

Since my page was first posted, I have received a number of emails asking about a high current power supply. I looked around, but couldnt find one that was suitable. So, I designed this. It is a linear supply, which might have a few of you rolling your eyes, but it takes very few parts, is simple to build and can supply huge currents

High Current Power Supply Circuit diagram :

Parts Table :

Part	Total Qty	Description
R1	1	680 Ohm 1/4 Watt Resistor
C1	1	20,000 - 50,000uF 20-40 Volt Capacitor
C2, C3	2	100uF 50 Volt Capacitor
C4	1	0.1uF 50 Volt Capacitor
C5	1	0.01uF 50 Volt Capacitor
D1	1	Zener Diode (See Notes)
Q1	1	2N3055 Or Other (See Notes)
T1	1	Transformer (See Notes)
BR1	1	Bridge Rectifier (See Notes)
S1	1	SPST 250 VAC 10 A Switch
MISC	1	Case, Line Cord, Heatsink For Q1, Binding Posts For Output

Notes :

1. D1 should be rated at about one volt higher than then desired output of the supply. A half watt diode will do.
2. Q1 can be a transistor similar to the 2N3055. I chose the 2N3055 for its availability and power handling (150 watts).
3. T1 should be about 5 volts higher than the desired output of the supply, and rated for about one amp more of current. The voltage overhead is required by the regulator section. The extra current is to keep the transformer from over heating.
4. The choice of BR1 will depend on the voltage and current of your transformer. The rectifier should be rated for 50 volts more than the transformer, and 5 amps more than the transformer.
5. The value of R1 will be smaller when supplying high currents. Expiriment until you get what you need.
6. Heatsink and fans are absolutely necessary!

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3V DC to 5V DC REGULATED POWER SUPPLY ELECTRONIC DIAGRAM

3V DC to 5V DC REGULATED POWER SUPPLY ELECTRONIC DIAGRAM

A 5V DC regulated output from 2 cells 3V DC batteries. The output current of the circuit is limited to 50mA. However, it still able to supply many microcontroller circuits. 3009 and 560R Resistor provide the 5V DC output, make up a voltage divider network.

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Add this Short Circuit Protection to Your Power Supply

A power supply unit is an indispensable unit for every electronic enthusiast and engineers working in the relevant field. Though today all of us use hi-tech power supply units having built-in protection, there are folks who still rely on ordinary types of power supply units with no protection facility.


The biggest enemy of all power supply units is a possible short circuit that might occur at its output terminals due to an accidental connection or due to the fault with the connected load.

There are various electronic circuits that might be employed with a power supply unit for checking this problem, however these circuits sometimes themselves are at risk of getting damaged due to the limitations with many electrical parameters.

A very innovative way of rectifying this problem has been shown in this article. A single relay is used for sensing as well as tripping the output from the involved malfunction.

Referring the circuit diagram, we see that a relay is connected directly to the output of the power supply DC output, however the connection is made through the N/O contacts of the relay. These contacts are also terminated as the output of the unit.

N/O means normally open, that means the contacts are open initially, which in turn keeps the output disconnected from the positive of the power supply.

Now when the shown push button is momentarily pushed, the N/O contacts are bypassed allowing the current to flow across the relay coil.

The relay coil energizes, closing the N/O contacts, which in turn latches and sticks to the position even after the push button is released.

The relay latch maintains this latched position as long as the output is used under normal conditions, but when a short is made or happens across the output terminals of the supply, voltage drops rapidly across the relay coil and it immediately trips, cutting OFF the supply to the output and in the course switches OFF the latch preventing the short hazard conditions.  

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Power on time delay circuit

This circuit is time delay circuit to power on.Most of electrical equipments burn due to power failures so this circuit is a best answer for that.
Note

# This circuit operates with 12V power supply

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Automatic AC Power Switch

Electrical appliances accidentally left on  in (holiday) homes left unoccupied for a  brief or a protracted length devour power  unnecessarily and may existing a fire hazard. Everyone shall be accustomed to those  nagging thoughts, a quantity of miles down the  highway from the home: “Did I remember  to change off the espresso machine? The  milds? The oven?” 

Circuit diagram :

Automatic AC Power Switch Circuit Diagram

Hotel rooms are regularly equipped with a  swap near the main door which allows the facility supply to the entire thing in  the room simplest when the plastic card (which  may contain a chip or have a magnetic strip  or a sample of holes) that serves because the room  secret's inserted. The circuit thought given here  to modify off gentles and different home equipment is  alongside the identical lines. The answer is distinctly easy. 

A reed contact is suited for the body of the main entrance door, and a matching magnet  is hooked up to the door itself such that when  the door is closed the reed contact is also  closed. To allow power to the house, press  S1 briefly. Relay RE1 will pull in and complete  the circuit for all of the AC powered home equipment in  the house. The relay will be held in even after  the button is liberated by means of the second relay contact and the reed contact (‘latching’ function). 

As quickly as the primary entrance door is  opened, the reed contact may even open.  This in flip releases the latch circuit and  consequently the relay drops out. The  various linked home equipment will thus  routinely and that inevitably be switched  off as quickly as the house is left. The circuit is mainly designed for  small vacation properties, where this mode  of operation is especially sensible. Of course, for any circuit that deals in AC  powerline voltages, we should mention  the next caution. 

Caution:

shock hazard! Construction and connection of this circuit  will have to simplest be carried out by suitably-qualified  personnel, and all applicable electrical safety  rules must be observed. In particular, it  is essential to be positive that the relay chosen is  acceptable to be used at domestic AC grid volt-ages and is suitably rated to hold the required  current.

http://www.ecircuitslab.com/2012/04/automatic-ac-power-switch.html

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4 X 15 Watt Mini Power Amplifier

A lot of electronic circuits in the domain of audio amplifiers are already been published here. This circuit is a little different because it is a four channel amplifier. Each channel of this amplifier can deliver an output of 15Watts into a 4 ohm speaker. The amplifier can be operated from a single 12V DC supply and this makes it possible to use this amplifier in car audio applications too.

4 X 15 Watt Mini Power Amplifier Circuit diagram :

The circuit is based on the 15W BTL X 2 channel audio power amplifier IC TA8215 from Toshiba. Even though chip is specifically designed for car audio applications it can be also used for home audio applications. Two TA8215 ICs are used here in order to obtain a 4 channel amplifier system. The circuit is designed almost exactly as per the application diagram in the ICs datasheet. Pins 7 and 19 are the Vcc pins of the ICs internal integrated power amplifier stages and these pins are connected to the positive supply. Pin 9 is the Vcc pin for ICs internal preamplifier and it is also connected to the positive supply. Pins 13 and 14 are the internal power amplifiers ground pins and they are tied together and connected to the ground.
The internal preamplifier’s ground pin (pin5) is connected to the common ground through a 10 Ohm resistor which makes the input ground separated from the common ground by a resistance of 10 ohms and this improves the noise rejection. The 100uF capacitor works as a power supply de-coupler. The resistor networks connected to the output lines of each amplifier improves the high frequency stability. The variable resistors (R3, R4, R12 and R13) works as the volume controller for the corresponding channels.

Notes :

• Assembling the circuit on a good quality PCB is a must for obtaining optimum sound quality.
• Use 12V DC for powering the circuit.
• The ICs must be fitted with adequately sized heat sinks.
• R3, R4, R12 and R13 serves as volume controllers.
• K1 to K4 can be 4 Ohm, 20W speakers.
• This amplifier circuit can be used in a variety of applications such as car audio systems, home theater systems, personal audio systems, public address systems etc.

Source : http://www.ecircuitslab.com/2012/08/4-x-15-watt-mini-power-amplifier.html

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1957 58 Dodge 4 Way Power Seat Wiring Diagram

1957-58 Dodge 4-Way Power Seat Wiring Diagram

(click for full size image)

The Part of 1957-58 Dodge 4-Way Power Seat Wiring Diagram:4 way seat adjusting switch, 30 amp circuit breaker, horizontal adjusting unit, battery,

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Power Supply Failure Alarm

Most of the circuit power supply failure alarm circuits require additional or external power supply. However, this circuit requires no additional power supply. The circuit uses a voltage of 5 volts to 15 volts. To adjust the voltage of this circuit, first connect the power source (5 to 15V) and change the position of potentiometer VR1 until the buzzer buzzer On to Off position.

If the power supply fails, resistor R2 will bias the transistor and the base will turn on the buzzer. Here is a picture series of power supply failure alarm :

 Power Supply Failure Alarm  Circuit

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Low Cost Dual Power Supply

This circuit shows how to symmetrically split a supply voltage using a minimum of parts - one LM380 power amplifier plus two 10µF capacitors. It was originally published in National Semiconductors AN69 and provides more output power than a conventional general-purpose op amp split power supply. Unlike the normal power zener diode technique, the LM380 circuit does not require a high standby current to maintain regulation. In addition, with a 20V input voltage (ie, for ± 10V outputs), the circuit exhibits a change in output voltage of only about 2% per 100mA of unbalanced load change. Any balanced load change will reflect only the regulation of the source voltage, Vin.

Circuit diagram:

Low-Cost Dual Power Supply Circuit Diagram

The theoretical plus and minus output tracking ability is 100% since the device will provide an output voltage at one-half of the instantaneous supply voltage in the absence of a capacitor on the bypass terminal. The actual error in tracking will be directly proportional to the unbalance in the quiescent output voltage. An optional 1MO potentiometer may be installed with its wiper connected to pin 1 of the LM380 IC to null any output offset. The unbalanced current output is limited by the power dissipation of the package.

In the case of sustained unbalanced excess loads, the device will go into thermal limiting as the internal temperature sensing circuit begins to function. And for instantaneous high current loads or short circuits, the device limits the output current to approximately 1.3A until thermal shutdown takes over or the fault is removed. For maximum output power (2.5W), all ground pins (3-5 & 10-12) should be soldered to a large copper area (the LM380 data sheet contains more details).

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Adjustable Stabilized Power Supply 0 15V 5A

Adjustable Stabilized Power Supply 0-15V / 5A

This
adapted ability accumulation can be adapted amid a few volts and 15V
with P1 and with P2 acclimatize the high absolute ( 15.0V ). R6 amount
is 0.7V / Imax area Imax is the best current. At Imax = 5A, R6 is
0.14Ω

T1 and T2 charge accept
heatsinks because ability losses are abundant at a low achievement
voltage and a Imax according accepted but you can affix the lamp L to
abate this losses.

I’ve body
this adjustable ability accumulation and works great! I achievement
you’ll adore it too and accept fun body this abundant counterbalanced
ability supply.

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5 to 15V Regulated Power Supply Rise

Regulated Power Supply

This project is a normal DC regulated power supply that is a variable DC voltage range from 5V to 15V. It can supply current up to  400mA to power the various circuits for your electronic projects. The voltage output is varied by using the potentiometer V.R1. In this circuit, the input line power supply is designed for 240V.A.C. If 110VAC input is used, alter the ratings of the varistor to 150VAC & the transformer ratio to 110V/12V. 

Fuse F1 is used as a protection in case theres any short circuit in the circuit. Varistor V1 is connected in parallel to the input of the line voltage to clamp the surge voltage from the line to a reasonable level that helps to protect the transformer & other circuitry. One time the voltage level surge to a high level beyond the ability of the varistor to absorb it, fuse F1 or varistor V1 or both will burn. If this circuit failed after a period of operation, check that the fuse & the varistor are still in nice condition or else replace them.

Diodes D1, D2, D3 and D4 are used to rectify the 12V.A.C voltage to DC voltage. Electrolytic capacitor E1 is used as a smoothing capacitor to reduce the ripple of the DC voltage. The DC voltage is fed in to the input of 7805 regulator where the output DC voltage is obtained. Changing the worth of VR1 will alter the output of the DC voltage. Capacitor C1 is used to filter out high frequency part from the power supply.

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Computer Power Supply for Battery Charger

Some workbenches can’t help ending up looking like a rats nest of cables and equipment, so its always an advantage if a piece of mains equipment can be removed from somewhere to free up an extra mains socket. Here we are using the ubiquitous PC as a battery charger. An unused serial interface port can supply enough current to charge (or trickle charge) low-capacity Nickel Cadmium (NiCd) batteries. You could for example, use the batteries in a radio and charge them during use.

The three serial port connections TxD, DTR, and RTS, when not in use, are at –10 V and can supply a current of around 10 to 20mA (they are short-circuit protected). The circuit shown supplies a charging current of approximately 30mA. If it is necessary to alter the polarity of the charging circuit then it is a simple job to reverse the diodes and using software, switch the port signals +10 V. Those interested could also write a software routine to automatically recharge the batteries.

Source : www.extremecircuits.net

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25W Hi Fi Power Amplifier Circuit

25 W Hi-Fi power amplifier circuit is a one of simple design that’s build by transistor NPN and PNP. The output devices are MJL4281A (NPN) and MJL4302A (PNP), and feature high bandwidth, excellent SOA (safe operating area), high linearity and high gain. Driver transistors are MJE15034 (NPN) and MJE15035 (PNP). All devices are rated at 350V, with the power transistors having 230W power dissipation and the drivers are 50W. The amp may also be operated at lower supply voltages for less power, but I do not recommend less than ±18V, which will provide around 15W into 8 ohms. This supply voltage (approximately) may be obtained by using a 15-0-15V transformer. This figure is show the circuit and operation of the circuit.


The supply voltage should be a maximum of ±25V. This supply is easily obtained from a 20-0-20V transformer. All resistors should be 1/4W or 1/2W 1% metal film for lowest noise, with the exception of R9, R10 and R15 which should be 1/2W types, and R13, R14 must be 5W wire wound. The bootstrap capacitor (C5) needs to be rated at least 25V, but the other electrolyc can be any voltage you have available. The potentiometer (VR1) must be a multi turn type, as the current setting is critical. Each of these amps will require a 0.25°C/W heat sink (very large). Consider using a fan or even water cooling to keep temperatures as low as possible.

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Stereo Low power audio amplifier

Audio amplifier circuit has a power output of 2 x 2.3 Watt, which uses IC KA2206, KA22061, LA4180, LA4182, LA4183, LA4550, LA4555, LA4558. The required voltage for at least 6 volts to 13 volts DC maximum. Component takes is a ic that I mentioned above one of them, and several capacitors elco.

This Schematics low power amplifier

Component Description
C1 = 1uF
C2 = 100uF
C3 = 100uF
C4 = 100uF
C5 = 0.1uF
C6 = 470uF

C7 = 1uF
C8 = 100uF

C9 = 100uF
C10 = 100uF

C11 = 0.1uF
C12 = 470uF

ICs can use the ic which I mention above for each ic datasheet can be seen itself.

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Low Power FM Transmitter Schematic

The circuit of the transmitter is shown in Figure 1, and as you can see it is quite simple. The first stage is the oscillator, and is tuned with the variable capacitor. Select an unused frequency, and carefully adjust C3 until the background noise stops (you have to disable the FM receivers mute circuit to hear this).

Because the trimmer cap is very sensitive, make the final frequency adjustment on the receiver. When assembling the circuit, make sure the rotor of C3 is connected to the +9V supply. This ensures that there will be minimal frequency disturbance when the screwdriver touches the adjustment shaft. You can use a small piece of non copper-clad circuit board to make a screwdriver - this will not alter the frequency.

The frequency stability is improved considerably by adding a capacitor from the base of Q1 to ground. This ensures that the transistor operates in true common base at RF. A value of 1nF (ceramic) as shown is suitable, and will also limit the HF response to 15 kHz - this is a benefit for a simple circuit like this, and even commercial FM is usually limited to a 15kHz bandwidth.

The Principle of works this application;
Q1 is the oscillator, and is a conventional design. L1 and C3 (in parallel with C2) tune the circuit to the desired frequency, and the output (from the emitter of Q1) is fed to the buffer and amplifier Q2. This isolates the antenna from the oscillator giving much better frequency stability, as well as providing considerable extra gain. L2 and C6 form a tuned collector load, and C7 helps to further isolate the circuit from the antenna, as well as preventing any possibility of short circuits should the antenna contact the grounded metal case that would normally be used for the complete transmitter.

The audio signal applied to the base of Q1 causes the frequency to change, as the transistors collector current is modulated by the audio. This provides the frequency modulation (FM) that can be received on any standard FM band receiver. The audio input must be kept to a maximum of about 100mV, although this will vary somewhat from one unit to the next. Higher levels will cause the deviation (the maximum frequency shift) to exceed the limits in the receiver - usually ±75kHz.

With the value shown for C1, this limits the lower frequency response to about 50Hz (based only on R1, which is somewhat pessimistic) - if you need to go lower than this, then use a 1uF cap instead, which will allow a response down to at least 15Hz. C1 may be polyester or mylar, or a 1uF electrolytic may be used, either bipolar or polarise. If polarised, the positive terminal must connect to the 10k resistor.

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35 Ampere Power Supply

To make 12Volt 35 Amp Power Supply such as those titles can using LM7812 voltage regulator as the regulator 12 Volt DC and as a power supply can use transistor  TIP2955 .

Series Power Supply 12Volt 35 Amp uses 6 units TIP2955 type power regulator transistors. I use a type MJ2955 TIP2955 not because packaging TIP2955 easier to install heatsink. The series 12Volt 35 Amp Power Supply can be loaded up to 35A depending on the travo which we attach. The series 12Volt 35 Amp Power Supply is very simple, because the voltage regulators make use of IC7812 which will leave a power regulator alone. For more details, series 12Volt 35 Amp Power Supply can be seen in thethe following figure .

12Volt 35Ampere schematic

If want the maximum currents up to 35A not only reduced the live circuit TIP2955nya power regulator, no need to 6 levels as seen in the image series 35 Ampere Power Supply 12Volt above.

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