Secret Diagram: Variable

Showing posts with label Variable. Show all posts

Friday, 20 January 2017

Variable DC Power Supply Rise Circuit Diagram

This Variable DC Power Supply (Rise) Circuit Diagram project provides the schematic & the parts list needed to construct a simple DC Power Supply from an input power supply of 7-20 V AC or 7-30V DC. This project will come in handy in case you use plenty of batteries for your basic electronics project.

Two DC voltage outputs are available; is a fixed regulated 5V for TTL use. The other output is variable from 5V upwards. The maximum output voltage depends on the input voltage. The specified maximum input DC voltage to the regulator is 35V. The maximum input voltage must be two volts higher than the regulated output voltage.

Variable DC Power Supply (Rise) Circuit Diagram

Variable DC Power Supply Circuit Diagram

The DC Power Supply circuit is based around the 7805 voltage regulator. It's only three connections input, output & ground & it provides a fixed output. The last digits of the part number specify the output voltage, e g. 05, 06, 08, ten, 12,15, 18, or 24. The 7800 series provides up to one amp load current & has on-chip circuitry to close down the regulator if any attempt is made to operate it outside its safe operating area.It can be seen that there's in fact separate circuits in this power supply. 7805 is directly connected as a fixed 5V regulator. The second 7805 has a resistor divider network on the output. A variable 500 ohm potentiometer is used to vary the output voltage from a maximum of 5V up to the maximum DC voltage depending on the input voltage. It will be about 2V below the input DC voltage.

The capacitor across the output improves transient response. The giant capacitor across the input is a filter capacitor to help smooth out ripple in the rectified AC voltage. The larger the filter capacitor the lower the ripple.

For tiny applications the heat sinks won't be needed. The tab on the regulator will dissipate 2W at 25 o C in air. (This is equivalent, for example, to an input voltage of 9V, an output of 5V & drawing 500 m A.) However, as your projects get bigger they will draw more current from the power supply and the regulators will operate at a higher temperature and a heat sink will be needed. You can basically add voltage & current meters to it and put it in to an appropriate plastic case connected to a transformer.

Trouble Shooting Procedure

An LED has been put in to the output of the fixed 5V regulator to indicate that the circuit is working. Poor soldering is the most likely reason that the circuit does not work. Check that all the soldering is done properly. Check that all parts are in their correct position on the PCB. Other items to check are to make sure that the regulators, electrolytic capacitor & bridge rectifier are inserted in the correct orientation.

Readmore → Variable DC Power Supply Rise Circuit Diagram

Friday, 9 December 2016

0 30V Stabilized Variable Power Supply with Current Control

This is high quality stabilized power supply circuit diagram. You will able to adjust the output voltage from 0 volt up to 30 volt DC. You also able to adjust the current output value from 0.002 A to 3 A. This variable power supply incorporates an electronic output current limiter that effectively controls the output current from a few mA (2 mA) to the maximum output of 3 A that the circuit can produce.

Component list:
R1 = 2,2 KOhm 1W
R2 = 82 Ohm 1/4W
R3 = 220 Ohm 1/4W
R4 = 4,7 KOhm 1/4W
R5, R6, R13, R20, R21 = 10 KOhm 1/4W
R7 = 0,47 Ohm 5W
R8, R11 = 27 KOhm 1/4W
R9, R19 = 2,2 KOhm 1/4W
R10 = 270 KOhm 1/4W
R12, R18 = 56KOhm 1/4W
R14 = 1,5 KOhm 1/4W
R15, R16 = 1 KOhm 1/4W
R17 = 33 Ohm 1/4W
R22 = 3,9 KOhm 1/4W
RV1 = 100K trimmer
P1, P2 = 10KOhm linear pontesiometer
C1 = 3300 uF/50V electrolytic
C2, C3 = 47uF/50V electrolytic
C4 = 100nF polyester
C5 = 200nF polyester
C6 = 100pF ceramic
C7 = 10uF/50V electrolytic
C8 = 330pF ceramic
C9 = 100pF ceramic
D1, D2, D3, D4 = 1N5402,3,4 diode 2A – RAX GI837U
D5, D6 = 1N4148
D7, D8 = 5,6V Zener
D9, D10 = 1N4148
D11 = 1N4001 diode 1A
Q1 = BC548, NPN transistor or BC547
Q2 = 2N2219 NPN transistor
Q3 = BC557, PNP transistor or BC327
Q4 = 2N3055 NPN power transistor
U1, U2, U3 = TL081, operational amplifier
D12 = LED diode

Readmore → 0 30V Stabilized Variable Power Supply with Current Control

Sunday, 4 December 2016

0 30V Stabilized Variable Power Supply with Current Control

Readmore → 0 30V Stabilized Variable Power Supply with Current Control

Tuesday, 15 November 2016

Supply Variable 1V to 9V Circuit using Power PC

This is a variable power supply which converts an input voltage from 12V SMPS / PSU a desktop computer, to an output voltage from 1.25 to 9 volts. This converter will be very useful for electronics hobbyists.

The circuit uses a LM317T regulator IC that can reach up to 1 ampere, the diode D1 protects against polarity reversal and the diode D2 keeps the output voltage from the input voltage increases when an inductive or capacitive load is connected to the output.Similarly, the capacitor C3 removes any residual noise of the line regulates the voltage potentiometer VR1.

Supply Variable 1V to 9V using Power PC Circuit Diagram

Readmore → Supply Variable 1V to 9V Circuit using Power PC