AC/DC - DC/DC

Automatic switch for batteries

Automatic switch for batteries

Nowadays the batteries are gaining more and more power, being the only components that fail to provide energy for portable electronic devices. The evolution is rapid, leading manufacturers electronic equipment to attempt to minimize the consumption of their products so that they can operate for several hours using simple batteries trade. In spite of the efforts of manufacturers, the device will absorb a zero power not yet invented. Thus, both small and if the current device is mathematically certain that at some point, after a few hours, days or ethdomades, the battery-drain '. The purpose of the circuit will describe below, is to keep 'alive' batteries for the maximum time, minimizing unnecessary consumption...

Dual supply for audio amplifiers

Dual supply for audio amplifiers

Most amps acoustic frequencies that make our readers, instead of a transformer power, sometimes required two or sometimes three. This tactic is more common in amplifiers 'High-End', where the altar of high fidelity are all eager to sacrifice their economies. In these cases the primary, all connected to the network of 220V, paralleled each other yet, through a single security, the nearest outlet. The problem that arises in such a connection is related with as such security. If the amplifier has two transformers, then the defendant one of them leads by one channel (or more generally a set of circuits), and if available, and a third, he'll have as sole purpose supplying circuit protection and control of others...

DC to DC converter electronic schematic

DC to DC converter electronic schematic

Those of you who frequently use devices that work on battery or you need a negative trend at the moment you have a single positive, will definitely look for a converter like the one described below. Constructing it, you can convert a positive voltage of a battery of 9 V to negative using well known integrated 555. The same circuit can also be used in cases those requiring two symmetrical lines of power, when available a single battery. The integrated TLC555 is the old bipolar NE555, manufactured with technology but CMOS. Unless you have this type of integrated, you might as well use an 7555. In this construction, the TLC555 is syndesmologimeno arranged in a ground unstable...

Low Power consumption 5V regulator circuit

Low Power consumption 5V regulator circuit

The special feature of the circuit shown below is the low consumption. With voltage n 9 at the entrance and no exit load, absorbs current 50 ma, which is certainly very small compared with a quiescent current 78L05. The components that comprise it are scarce. Just a reference voltage source, formed by the T1 and the IC 1 and an amplifier consisting of the IC2 and T2 so we have to output the desired voltage stabilizer. The trend that emerges at the output of IC 1 increased to 1,22 V. Using the IC2 and the P1 is set so that the output of the circuit is n equal to 5 exactly at the entrance of the circuit can be imposed voltage between 6.5 ??? 30 V DC, while the maximum output current reaches 1 mA for the better functioning of the stabilizer, transistors T and T 1 a 1 b should be possible similar characteristics. That is why we preferred a 'double' type transistors MAT02 or alternatively one of the MAT01, SSM2210 or LM394...

Photocell power supply (MAX630)

Photocell power supply (MAX630)

This circuit delivers either 4.8 or 7.2 V regulated at 15 mA with a 3-V input from a bank of photocells. R1 should be 453 k? for a 7.2-V output and 274 k? for a 4.8-Vdc output. Regulator efficiency is around 70%. This should be considered when selecting suitable solar cells. ..

Delay switching for power amplifiers

Delay switching for power amplifiers

This delay can be used in power amplifiers, to prevent the fuses fail when the amplifier is turned on. The circuit is very simple with a relay which turned on when C2 and C3 are charged. If the relay has not been applied, the resistors used to control connected to feed. If after some time the relay attracts the bridge resistors. Watch out for your own safety when building this circuit. On the whole circuit is power. F1 should be the value of having the fuse that normally would be used...

Single to double power with CA3140

Single to double power with CA3140

Another circuit for a balanced diet from a single voltage network. In fact, this is a uitbreding the other voltage divider circuit using a some power darling tons as buffer. This buffer can deliver a 200 to 300 mA...

Basic power supply schematic

Basic power supply schematic

The simplest power supply voltage regulator can be created with the 78xx series. The voltage regulator is available in different voltages (see table). The controller is 100 mA, 1 or 2 A provides. C2 is a decoupling capacitor. He must therefore as close to the controller are placed. The parts must be adapted to the supply voltage and current. At low voltages (below 5 V) can be reduced to C1 1000 uF. At voltages above 15 V and 1 A should be C1 4700 uF. With output currents above 1 A, the diodes are replaced by 1N5401. ..

5 A stabilized power supply

5 A stabilized power supply

This is a simple but powerful nutrition that less than 5 A can deliver. The circuit works by using a normal type 78xx voltage regulator and a buffer transistor. When the output current over 200 mA, then take over the T1, which limits the maximum output current is 5 Amps. The 1978 series regulator is available from 5 to 24 volts. In the place of the xx is the voltage, so 7812 for a 12 volt regulator. Take the AC in 5% higher than the desired output voltage. In that case, one under the wrinkle. MJ is a T1 (E) in 2955. This higher output currents must be well chilled. ..

10A stabilized power supply

10A stabilized power supply

This is a heavy diet, which can deliver 10A stabilized. The circuit is built around a normal 78xx controller, but for extra power equipped with T1. For the 78xx can be taken any type. Keep in mind that the input voltage of 3V regulator must be higher as the output nected. See 78xx power for the available controllers. T1 must be a large heat sink mounted when large capacities are diminished. A negative variant of this diet is here to find. ..

5 Volt to 12 Volt bi-directional lamp sequencer

5 Volt to 12 Volt bi-directional lamp sequencer

The circuit below is designed to be used with the bi-directional lamp sequencer shown above on this same page. Two additional transistors are used to increase the current from the 74HCT138 decoder to control 12 volt 25 watt lamps. A 6.8 volt/1 watt zener diode is used in series with the ground connection of all the CMOS ICs (74HC14, CD4516 and 74HC138s) so that the total voltage across the CMOS devices will be about 5.2 volts and the outputs will move from +12 to about +7 when selected. ..

0-28V Variable power supply II

0-28V Variable power supply II

Another method of using opamps to regulate a power supply is shown below. The power transformer requires an additional winding to supply the op-amps with a bipolar voltage (+/- 8 volts), and the negative voltage is also used to generate a reference voltage below ground so that the output voltage can be adjusted all the way down to 0. Current limiting is accomplished by sensing the voltage drop across a small resistor placed in series with the negative supply line. As the current increases, the voltage at the wiper of the 500 ohm pot rises until it becomes equal or slightly more positive than the voltage at the (+) input of the opamp. ..

3-24V / 3A power supply

3-24V / 3A power supply

This regulated power supply can be adjusted from 3 to 25 volts and is current limited to 2 amps as shown, but may be increased to 3 amps or more by selecting a smaller current sense resistor (0.3 ohm). The 2N3055 and 2N3053 transistors should be mounted on suitable heat sinks and the current sense resistor should be rated at 3 watts or more. Voltage regulation is controlled by 1/2 of a 1558 or 1458 op-amp. The 1458 may be substituted in the circuit below, but it is recommended the supply voltage to pin 8 be limited to 30 VDC, which can be accomplished by adding a 6.2 volt zener or 5.1 K resistor in series with pin 8. ..

9V to 5V converter schematic with 555

9V to 5V converter schematic with 555

A 555 timer can be used to generate a squarewave to produce a negative voltage relative to the negative battery terminal. When the timer output at pin 3 goes positive, the series 22 uF capacitor charges through the diode (D1) to about 8 volts. When the output switches to ground, the 22 uF cap discharges through the second diode (D2) and charges the 100 uF capacitor to a negative voltage. The negative voltage can rise over several cycles to about -7 volts but is limited by the 5.1 volt zener diode which serves as a regulator...

220 V LED Night light

220 V LED Night light

This Is a capacitor power supply. This is a very small currents of energy-effective, because it has very little loss, much smaller than the miniature transformer. Capacitor impedance is inversely proportional to frequency. This is a great disadvantage when the grid appear in the short interference pulses caused by switching on large appliances with inductive load character. For such a limiting pulse capacitor (C1 here) is practically a short circuit and load through a short period of much higher current. LEDs are the glitches very sensitive and easily damaged or destroyed directly. ..