High Current 5V DC Power Supply

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.

The LM317 will deliver more than 1A of electric current to drive the bases of the pass transistors and assumming a gain of 10 the combination ought to supply 15A or even more. The LM317 normally operates with a voltage variation of 1.2 between the output terminal and adjustment terminal and needs a minimal load of 10mA, so a 75 ohm resistor was selected that will draw (1.2/75 = 16mA). This same current flows via the emitter resistor of the 2N3904 which generates about a 1 volt drop across the 62 ohm resistor and 1.7 volts at the base. The output voltage is set using the voltage divider (1K/560) so that 1.7 volts is used to the 3904 base when the output is 5 volts. For 13 volt operation, the 1K resistor could be altered to about 3.6K. The regulator has no output short circuit protection so the output most likely ought to be fused.

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LM317T Voltage Regulator Circuit with Pass Transistor

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.

Sealed Lead Acid (SLA) 12V Battery Charger with Current Limiting

This is the circuit design of Smart Sealed Lead Acid (SLA) 12V Battery Charger featuretwith Current Limiting. The charger uses a two step process for charging SLA batteries – a current limited ‘fast’ mode followed by a constant voltage ‘float’ mode. Maximum charging current is 1A. An onboard LED indicates when the charger is in ‘fast’ mode. When the LED goes out the battery is charged and the charger has switched to ‘float’ mode.

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.)

Power Supply Adapter

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