Power Supply Adapter

This is the schematic diagram of voltage regulator circuit with pass transostor. The regulator is based regulator IC of LM317T. The LM317T output current can be raised by utilizing an additional power transistor (on circuit, it is 2N2955) to share a portion of the total current. The amount of current sharing is established with a resistor placed in series with the LM317 input and a resistor placed in series with the emitter of the pass transistor. In the above scheme design , the pass transistor will start conducting when the LM317 current reaches about 1 ampere, due to the voltage drop across the 0.7 ohm resistor. Current limiting happens at about 2 amperes for the LM317 which will drop about 1.4 volts across the 0.7 ohm resistor and make a 700 millivolt drop across the 0.3 ohm emitter resistor. Thus the total current is limited to about 2+ (.7/.3) = 4.3 amperes.

This is the high current dc power supply circuit with 5V output. The high current regulator utilizes an extra winding or a separate transformer to deliver power for the LM317 regulator so that the pass transistors can run closer to saturation and increase performance. For excellent performance the voltage at the collectors of the two parallel 2N3055 pass transistors ought to be near to the output voltage. The LM317 needs a couple extra volts on the input side, plus the emitter/base drop of the 3055s, plus whatever is lost across the (0.1 ohm) equalizing resistors (1volt at 10A), so a separate transformer and rectifier/filter circuit is utilized which is several volts higher than the output voltage.

Here the schematic design of 9V dual polarity power supply from 9V battery. Dual-voltage power supply is necessary particularly for running the op-amps and some of the instrumentation amplifiers. Some low-power audio pre-amplifiers also use dual-voltage power source. This circuit delivers both +9V as well as -9V DC output from a single 9V battery. It contains timer IC NE555 (IC1), negative-voltage regulator IC 7909 (IC2) along with several discrete parts.

This is the unregulated Split power supply circuit, intended to supply the hi-fi audio amplifier. This power supply circuit is very simple, and no great skill is needed to assemble this circuit.

This is the very simple general purpose variable power supply capable of delivering 0-15V DC output with about 1A electric current. The power supply circuit has regulated output and can be used for most small electronic circuit application.

Here the low power 12V transformerless power supply circuit with full-wave rectification. A lot of circuits could be powered straightaway in the electric mains using the support of a series capacitor (C1). The problem with this method is the fact that typically only one half cycle of the mains wave-form can be used to deliver a DC voltage. An obvious option is to work with a bridge rectifier to accomplish full-wave rectification, which improves the amount of current that can be delivered and makes it possible for the filter capacitor to become smaller sized. The associated circuit in fact does this, but in a clever manner that makes use of fewer parts. Right here we take benefit of the reality that a Zener diode can also be a standard diode that conducts electric current in the forward direction. During one half wave, the current flows via D1 through the load and back via D4, whilst during the other half wave it flows via D3 and D2. Keep in mind that with this circuit (and with the

Above diagram is the circuit of Lithium-ion (Li-ion) battery charger which built based single chip MAX1879. This is the simple and low cost battery charger for single-cell Li+ battery that does not dissipate power (no heat. The MAX1879, in conjunction with the AC linear transformer adapter and a PMOS FET, allows safe and fast charging of a single Li+ cell. The MAX1879 is not only an inductorless required solution, but also the lowest power dissipated solution among single-cell Li+ battery chargers.