Mini Power Supply | Electronic Project Circuits

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Adjustable voltage output control by 2SC458

This again the one circuit that use in fining value output voltage, for apply give straight with the requirement of load be the circuit that is simple and have no result temperature way of the joint junction of transistor. Vout control 0V-30V at 0.1A

The principle works be transistor Q1 2SC458 that built model common-emitter amplifier, which perform fine decrease input voltage get down then heal volt that give may but at collector voltage compare with ground. Which get from the combination of voltage at base – emitter pin (0.6V) with VZener diode (6.2V) already fine the value of a resister can fine the value VR1 help transistor part Q2 2SC458 perform be compared as power supply current source and current that fixed. By current at flow come in the way base pin of Q2 and when Q2 bias current. That already Voltage output get, with fining that a resister VR1 during 5.8V-15.8V. By have R3 and C1 perform be RC Filter caution. This circuit power current source get 100mA topmost should apply to load that use current low.

Be the first to comment - What do you think? Posted by admin - May 14, 2010 at 10:12 pm

Categories: Power supply, Variable Regulator Tags: Adjustable power supply schematic, C458, mini power supply

Variable DC Power Supply Voltage range 0.7 – 24V, Current limiting range 50mA – 2A

Voltage range: 0.7 – 24V

Current limiting range: 50mA – 2A

Device purpose:
A Variable DC Power Supply is one of the most useful tools on the electronics hobbyist’s workbench. This circuit is not an absolute novelty, but it’s simple, reliable, “rugged” and short-proof, featuring variable voltage up to 24V and variable current limiting up to 2A. It’s well suited to supply the circuits shown in this website. You can adapt it to your own requirements as explained in the notes below.
Parts:
P1____________500R Linear Potentiometer
P2_____________10K Log. Potentiometer
R1,R2___________2K2 1/2W Resistors
R3____________330R 1/4W Resistor
R4____________150R 1/4W Resistor
R5______________1R 5W Resistor
C1___________3300Î…F 35V Electrolytic Capacitor (see Notes)
C2______________1Î…F 63V Polyester Capacitor
D1,D2________1N5402 200V 3A Diodes
D3_____________5mm. Red LED
Q1____________BC182 50V 100mA NPN Transistor
Q2____________BD139 80V 1.5A NPN Transistor
Q3____________BC212 50V 100mA PNP Transistor
Q4 __________2N3055 60V 15A NPN Transistor
T1_____________220V Primary, 36V Center-tapped Secondary 50VA Mains transformer (see Notes)
PL1____________Male Mains plug
SW1____________SPST Mains switch
Device purpose:
A Variable DC Power Supply is one of the most useful tools on the electronics hobbyist’s workbench. This circuit is not an absolute novelty, but it’s simple, reliable, “rugged” and short-proof, featuring variable voltage up to 24V and variable current limiting up to 2A. It’s well suited to supply the circuits shown in this website. You can adapt it to your own requirements as explained in the notes below.

Notes:
P1 sets the maximum output current you want to be delivered by the power supply at a given output voltage.
P2 sets the output voltage and must be a logarithmic taper type, in order to obtain a more linear scale voltage indication.
You can choose the Transformer on the grounds of maximum voltage and current output needed.
Best choices are: 36, 40 or 48V center-tapped and 50, 75, 80 or 100VA.
Capacitor C1 can be 2200 to 6800uF, 35 to 50V.
Q4 must be mounted on a good heatsink in order to withstand sustained output short-circuit.
In some cases the rear panel of the metal box in which you will enclose the circuit can do the job.
The 2N3055 transistor (Q4) can be replaced with the slightly less powerful TIP3055 type.
Excellent quality-price ratio: enjoy!
source: RED Free Circuit Designs

Be the first to comment - What do you think? Posted by admin - September 17, 2007 at 12:27 pm

Categories: Power supply, Variable Regulator Tags: current limit, mini power supply, Variable-DC-Power-Supply

Mini Power Supply 9V to Isolated 9V for LCD Panel Meter

Did you ever install one of those low-cost LCD panel meters in a project only to discover that it requires a floating power supply? I just did! The meter cannot share a DC ground with the voltage to be measured. The above circuit came to the rescue. It draws about 4 or 5 mA from the 9 volt supply and can supply up to 2 mA at 9 volts to the LCD meter or other load but the two capacitors isolate the grounds. Works like a champ! Also see Craig’s regulated version.

Read More Source :http://www.techlib.com/electronics/regulators.html
Thank you.