6 V to 12 V Power Supply Inverter

This inverter circuit can provide up to 800mA of 12V power from a 6V supply. For example, you could run 12V car accessories in a 6V (British?) car. The circuit is simple, about 75% efficient and quite useful. By changing just a few components, you can also modify it for different voltages.

6 V to 12 V Power Supply Inverter Circuit Diagram

Part List:

R1, R4 2.2K 1/4W Resistor
R2, R3 4.7K 1/4W Resistor
R5 1K 1/4W Resistor
R6 1.5K 1/4W Resistor
R7 33K 1/4W Resistor
R8 10K 1/4W Resistor
C1,C2 0.1uF Ceramic Disc Capacitor
C3 470uF 25V Electrolytic Capcitor
D1 1N914 Diode
D2 1N4004 Diode
D3 12V 400mW Zener Diode
Q1, Q2, Q4 BC547 NPN Transistor
Q3 BD679 NPN Transistor
L1 See Notes
MISC Heatsink For Q3, Binding Posts (For Input/Output), Wire, Board

Solar Panel Current Meter

This circuit is used to measure the current from a solar panel. It has very low power loss for currents in the 0-10A range. It also works as a general purpose DC current meter. The circuit can be used on either the positive or negative side of a DC circuit.

Solar Panel Current Meter

 

Specifications

 

Measured Current: 0-10 Amps DC
Circuit Voltage: Will work with DC circuits at any practical voltage.
Accuracy: approximately 2%, depending on the meter movement.

Theory

 

The current to be measured flows through the 0.01 ohm resistor which causes a small voltage drop across the resistor. The 100 microamp meter is set up with the series 50 ohm and 500 ohm variable resistor in a voltage measurement configuration to measure this voltage drop. The 500 ohm variable resistor is used to adjust the meter's full scale reading. The 50 ohm resistor limits the maximum current to the meter no matter what setting is on the 500 ohm resistor, this protects the meter from passing too much current and burning up. The series resistance of the meter, 500 ohm (or less) variable resistor and 50 ohm resistor should total 1000 ohms. Different meters may require a different variable resistor to achieve the 1000 ohm value.

Construction

 

Build the meter into a metal box with the meter and two connectors mounted on the outside of the box.

Alignment

 

Put the meter circuit in series with a known current meter such as a digital VOM meter set to measure current. Run a known current through both meters. Adjust the 500 ohm resistor until both meters read the same current. A good way to get a known current is to put a 12V lead acid battery in series with a 2 ohm 100 watt current limiting resistor. This will produce approximately 6 Amps of current. Put the two meters in series with this loop and adjust for the same reading. Beware, the resistor will get fairly hot in a short time.

Use

 

Connect this circuit in series with a nominal 12V or 24V solar panel array. The meter can go in either the positive or negative side of the solar panel circuit. The current flowing through the solar panel to the load will be shown on the meter.

Parts

 

1x 100 microamp DC meter
1x 0.01 ohm 5 W resistor
1x 50 ohm 1/4 W resistor
1x 500 ohm 10 turn variable resistor
2x banana plugs or a 2 pin screw type terminal block.
1x metal box

Increasing 78xx Voltage Regulator Current

Shown in the figure is an IC voltage regulator (also known as stabilizer), designed to increase its current output with the use of an outboard pass transistor. Voltage regulators are designed to produce positive inputs, such as 78xx series, and negative inputs, such as 79xx series. Using this circuit will help increase the current output from a 78xx series regulator. Alternatively, 79xx series can also be used with an NPN type of transistor.

Using a power transistor enables additional current to be loaded while sustaining a steady voltage. But keeping in mind for the limit of input voltage as it should be a few volts above the output voltage. Regulators like 7812, having a 12V output can be set to produce 20V output.  Some 78xx series can surpass up to 36 volts input. Having a high power difference could lead to an overheat and would require sufficient heat sink. Without the heat sink, the transistor might collapse. Lower input could also cause failure due to the decrease in temperature. Power dissipation can be computed as the product of the voltage and the current  P = V * I.
Source:www.zen22142.zen.co.uk

Low Voltage Power Supply Without Transformer

The circuit diagram was designed to create a power supply without utilizing any transformer circuit. This circuit illustrates the advantages as well as the safety precautions to keep in mind.

Power supplies are devices accustomed to provide electrical or other sort of energy to a load or cluster of load. A type of power supply that makes use of a transformer is the AC powered linear power supply. The voltage from the wall socket is converted by the transformer to produce a normally lower voltage. Switched-mode and AC/DC power supplies are the types that does not utilize the presence of transformers. These transformers are responsible for transmitting electrical supply from one circuit to another through its coils (windings).

Designing a transformerless power supply makes it more suitable for smaller installations, in any location, where the area may be limited. The circuit can manage the high current coming from the mains by supplying 12 Volts at 20mA. The reason behind using capacitive reactance rather than resistance is the fact the the type of current flowing into the circuit is alternating. It can also be used with fluctuating DC supply. The reactance adapts with the way the components react in the circuit in terms of frequencies. A fusible resistor can also be used to provide more safety.

As an output device, optical sensors are preferred by measuring the intensity change of light when the power is increased among other controllers like temperature controllers, light switches or timers. The capacitor C1 are connected across the mains supply to act as restrainer. These capacitors are usually tagged with safety standard measures, although they are usually more expensive type rather than ordinary capacitors. Placing two capacitors in parallel or increasing the value can give way to additional current.

The two zener diodes are responsible for supplying the low voltage because these types of diodes controls the output by setting their breakdown or desired voltage, as they flow to the rectifier. The rectifier is responsible for converting the AC to DC. Opposite conversion form DC to AC uses an inverter. If the circuit would require an output higher than 40mA, transformers would be more significant to use.

The comparison between transformerless and transformer-based power supplies is not easy to identify due to the technologies that each one offers in the market. But the primary difference between the two are the physical dimension, noise, efficiency and the intensity of harmonic distortion that they produce.
Source:www.zen22142.zen.co.uk

L200 Variable Power Supply

The circuit was designed for a power supply that can be adjusted or altered depending on the pre-set value by using a L200 volatge and current regulator.

Designing a power supply with a flexible 5-pin L200 voltage regulator makes it self-sufficient for the limits in voltage and current. It has an adjustable output current up to 2 Amp, adjustable output voltage down to 2.85 Volts, input overvoltage protection, short circuit protection, output transistor protection, thermal overload protection, low standby current drain and low bias current on regulation pin.The L200 can be used to substitute fixed voltage regulators and reduces the need to store a range of fixed voltage regulators.

The primary rating of the winding of the transformer depends on the input source but the secondary rating must generate 12 Volts running 2 Amp. Controlling the current is limited by the 47-ohm resistor while the voltage output is regulated by the 10K-ohm resistor. The circuit will produce zero voltage output if the current will go beyond the limit.

For safety purposes, all connections in the transformer should be properly insulated especially when dealing with the mains input. A plastic bobbin with 2 chambers should be used for the primary and secondary coils. No transformer is totally safe, but keeping in mind the safety ways in handling live circuits can prevent such harm.

Source:www.zen22142.zen.co.uk/Circuits/Power/l200var.html

Low Voltage Power Supply Without Transformer

The circuit diagram was designed to create a power supply without utilizing any transformer circuit. This circuit illustrates the advantages as well as the safety precautions to keep in mind.

Power supplies are devices accustomed to provide electrical or other sort of energy to a load or cluster of load. A type of power supply that makes use of a transformer is the AC powered linear power supply. The voltage from the wall socket is converted by the transformer to produce a normally lower voltage. Switched-mode and AC/DC power supplies are the types that does not utilize the presence of transformers. These transformers are responsible for transmitting electrical supply from one circuit to another through its coils (windings).

Designing a transformerless power supply makes it more suitable for smaller installations, in any location, where the area may be limited. The circuit can manage the high current coming from the mains by supplying 12 Volts at 20mA. The reason behind using capacitive reactance rather than resistance is the fact the the type of current flowing into the circuit is alternating. It can also be used with fluctuating DC supply. The reactance adapts with the way the components react in the circuit in terms of frequencies. A fusible resistor can also be used to provide more safety.

As an output device, optical sensors are preferred by measuring the intensity change of light when the power is increased among other controllers like temperature controllers, light switches or timers. The capacitor C1 are connected across the mains supply to act as restrainer. These capacitors are usually tagged with safety standard measures, although they are usually more expensive type rather than ordinary capacitors. Placing two capacitors in parallel or increasing the value can give way to additional current.

The two zener diodes are responsible for supplying the low voltage because these types of diodes controls the output by setting their breakdown or desired voltage, as they flow to the rectifier. The rectifier is responsible for converting the AC to DC. Opposite conversion form DC to AC uses an inverter. If the circuit would require an output higher than 40mA, transformers would be more significant to use.

The comparison between transformerless and transformer-based power supplies is not easy to identify due to the technologies that each one offers in the market. But the primary difference between the two are the physical dimension, noise, efficiency and the intensity of harmonic distortion that they produce.
Source:www.zen22142.zen.co.uk/Circuits/Power/tps.htm

Dual Polarity Regulated Power Supply

The circuit design of this dual polarity power supply is regulated with the use of a positive (78xx) and negative (79xx) voltage regulators.

Dual polarity power supply are created mostly to power up operational amplifier circuits and other circuits that require dual supply voltage. The voltage is adjustable, requires a few parts, and easy to build. The circuit utilizes 7815 regulator for the positive supply while 7915 voltage regulator for the negative supply.

The monolithic IC 7815 positive voltage regulator is designed for use in several ways of applications including on board regulation. It makes use of internal current limiting, safe area compensation and thermal shutdown. It can produce output currents in excess of 1 Amp with enough heat sinking. It can be used with external components to obtain flexible voltages and currents, although it is designed primarily as a fixed voltage regulator. The negative voltage regulator 7915 employs the same features as with 7815 which makes it also notably rough for any operating conditions.

The rating of the transformer’s primary depends on the region of the supplied voltage. To allow losses on both regulators, the secondary coil should be 18 volts at 1 amp rating. Since the circuit might operate under 120, 220 or 240 volts, it’s a prerequisite for the circuit to be enclosed in a case where fans or heat sinks were usually required.

LM723 Variable Power Supply with Over-Current Protection

The circuit design was intended to create an adjustable power supply over a range of 1.3V to 12.2V at 1A and be able to provide protection for over-current by utilizing LM723 regulator.

 Terminology

• LM723 – a positive NPN standard voltage regulator mainly designed for series regulator applications which can be utilized for both foldback and linear current limiting due to its very low standby current drain circuit
• Voltage Regulator – an electrical or electronic device created for the purpose of maintaining a constant voltage level of a power source within the suitable limits
• 2N3055 – a complementary Silicon Epitaxial-Base planar NPN transistor mounted in Jedec TO-3 metal case for use as power transistor

Circuit Explanation
The integrated voltage regulator LM723 will supply 150 mA of output currents but any desired load current can be provided by adding external transistors for output currents in excess of 10A. This can be used as a linear or switching regulator since its output voltage can be adjusted from 2 Volts to 37 Volts while the input voltage can be at 40 Volts maximum. The range of variations of input voltage and load current can be kept at constant using this voltage regulator.

In this design, the DIL14 plastic packaged LM723 performs with 9.5V to 40V input DC voltage while having an output voltage that is not more then 6V to 7V below the input will lead to 150 mA current source from  the IC. The difference between the input and the output DC voltage plus the current is proportional to the amount power being dissipated by the transistor T1 as it accepts all the current brought by the load, thus requiring a heatsink with a heat conductive value of 5K/W. T1 is made from 2N3055 which is intended for series and shunt regulators, for output stages and high fidelity amplifiers, and for power switching circuits. The output stage of the integrated circuit will be less loaded when an external pass transistor is used which will conduct at emitter-follower mode. This will in turn cause T1 to conduct at base-emitter mode thereby producing a major resistance in the IC.

Both ceramic capacitors must be positioned closer to the integrated circuit to prevent undesired oscillations, which the LM723 is prone to, since ceramic capacitors have high frequency coefficient of dissipation. Having these capacitors directly soldered would be too much for the IC since the operating temperature of the IC is in the range of -55ᵒC to +125ᵒC

Application
Voltage regulators are used for several advantages in areas where uncontrolled voltage varies more than the accepted voltage of equipment which could be harmful and damaging. In motor vehicles, it matches the charging requirements of the battery and electrical load to the output voltage of the generator by rapidly switching from one to another of three circuit states using a dual pole switch loaded with spring. To keep a recommended range of voltage supplied to a consumer, regulators are used by alternating current distribution feeders or large scale power distributions or substations. This is useful in protecting the equipment using electricity by minimizing the variations in voltage.  The two types of regulators being used are step regulators where the current supply is controlled and the induction regulator where an induction motor adjust the voltage by supplying a secondary which smoothens the feeder line’s current variations.
The LM723 voltage regulators are widely used for wide range of applications such as a temperature controller, a current regulator, or a shunt regulator. Also, DC power supplies in electronic equipment are using voltage regulators.

Source:zen22142.zen.co.uk/Circuits/Power/723psu.htm