Power Supply Circuit: regulator

Showing posts with label regulator. Show all posts

Monday, May 28, 2007

LM338 Power Supply Regulator 13.8V 5A

Source :: http://users.otenet.gr/~ahisrod/power_supply_13_8V_5A_with_LM338.htm

Many times we needed one relatively powerful supply in order to we supply various appliances with + 13.8V, as transceivers CB, charge lead-acid batteries, etc. The circuit it uses known completed that is capable gives in the his exit, current in continuous operation 5A and 12A peak current. It does not only need few external component. Exist a point which it will be supposed you are careful in the drawing and in board. Board has been drawn so as to exist the possibility of using also two case types completing. In the first case the IC1 in case TO-220 is placed above in pcb, in second with case TO-3, it can it�s placed above in heatsink and terminal his they are connected in the connector G3, in this case, certain we leave empty the place of IC1 above in pcb. A other point is the refrigeration of rectifier B1. If it�s placed above in pcb, then it will be supposed clinch on his piece aluminium in form U, in opposite case, if the rectifier B1 is placed except pcb should clinch in a point in his chassis and terminal are connected with suitable cross-section cables in the corresponding points above in pcb. The regulation of voltage in + 13.8V become with the trimmer TR1, (multiturn). The IC1 should in every case be placed on one suitable heatsink, which good is supportable by one fan. All the connections by the circuit become with big cross-section cables , beacause the current that passes from in them is enough high. If they are not used the connectors that appear in pcb, then you can place pins or solderer the cables at straight line above in pcb

R1=270R 1/4W 2% C4-5=10uF 25V T1=220Vac/15VAC - 8A Mains Transformer
TR1=4k7 (Multiturn) D1-2=1N4002 (1A/100V) S1=2 Pole Single Throw Mains Switch
C1=10000uF 40V B1=25A Bridge Rectifier F1=250mA Fuse
C2-3=100 nF 100V Polyester IC1=LM338

Friday, May 25, 2007

Small Variable Power Supply 1.3-12V 1A by IC LM723

Circuit : Miroslav Adzic - Serbia & Montenegro
Source : http://www.zen22142.zen.co.uk/Circuits/Power/723psu.htm

Description:
Features: 1.3-12.2 V, 1 A, over-current protection. This is a simple but reliable device based one of the oldest integrated voltage regulators of them all - the LM723.

Notes:
R2 sets the output voltage. The maximum current is determined by the value of R3: the over-current protection circuitry inside the LM723 senses the voltage across R3 and starts shutting the output stage off as soon as this voltage approaches 0.65 V. This way the current through R3 can never exceed 0.65/R3, even if the output is shorted.

C3 and C4, both ceramic, must be placed as close as possible to the integrated circuit, because the LM723 can be prone to unwanted oscillations. It is not an overkill to solder them directly (and very carefully) to the pins of the IC. All other connections should also be kept short.

The LM723 works with input DC voltages from 9.5 to 40 V and the IC itself can source some 150 mA if the output voltage is not more than 6-7 V below the input. When an external pass transistor is used (in the usual emitter-follower mode), the base-emitter junction of T1 represents a significant resistance and the integrated circuit's output stage is relatively lightly loaded. All the current drawn by the load passes through T1 and it dissipates an amount of power that is directly proportional to the current and the difference between the input and the output DC voltage.

L200 Current Limiting Power Supply

Circuit : Ron J
Email Ron
Source : http://www.zen22142.zen.co.uk/Circuits/Power/clps.htm

Description:
This is a 1-amp variable-voltage PSU. It adjusts from about 3v to 24v: and has the added feature that you can limit the maximum output current. This is invaluable when (for example) you power-up a project for the first time or soak-test a piece of equipment.

Notes:
SW3 is the on/off switch. It also lets you choose between the output with the current limit and the one without. SW2 provides a selection of three different limits. You can increase or decrease this number if you wish. The limits are fixed by R4, R5 & R6. They are set at 10mA, 25mA & 65mA respectively; but you can choose whatever limits you like. If you try to draw a current above the limit you've selected, the output voltage will fall. Thus, the voltmeter indicates when the load on the output is excessive.

The housing should be well ventilated. The heatsink is a folded strip of aluminium about 2mm thick, 18cm long and 6cm tall. SW1 allows you to choose between the (3v to 12v) and (3v to 24v) outputs. This reduces the power the heatsink has to dissipate when the output voltage is low.

The drawing of the front panel is intended mainly as a wiring diagram - you can choose your own layout. The pin spacing of the L200C doesn't suit the stripboard; but with a little persuasion it can be made to fit. Since the limiting resistors may have a relatively low value, a few ohms between the contacts of the wafer-switch will have a significant effect. If (with time) you find that the limits have fallen, use a spray-cleaner on the switch.

Power Supply Regulator by IC L200

Circuit : Andy Collinson
Email: anc@mitedu.freeserve.co.uk
Source : http://www.zen22142.zen.co.uk/Circuits/Power/l200.html

Power supply with voltage and current regulation built around the L200C regulator.
Notes:
The versatile 5 pin L200C regulator offers both voltage and current regulation in a single package. The IC also features thermal shutdown and input over voltage protection up to 60 Vdc. The package is also available as L200CV which has straight pins for mounting onto a PCB.

Specifications:
DC Input Voltage: 40V max.
Peak Input Voltage: 60V max. for 10ms
Output Voltage Range: 2.85 to 36V
Output Current Range: 0.1 to 2A
Quiescent Current: 4.2mA
Output Noise: 80uV

Boosting Regulator Current for IC 78xx by MJ2955

Source :: http://www.zen22142.zen.co.uk/Circuits/Power/boosti.htm

IC 78xx series of voltage regulators are available with different current outputs, you can boost
the available current output with this circuit. A power transistor is used to supply extra current to the load
the regulator, maintaining a constant voltage. Currents up to 650mA will flow through the regulator, above
this value and the power transistor will start to conduct, supplying the extra current to the load. This should
be on an adequate heat sink as it is likely to get rather hot. Suppose you use a 12v regulator, 7812. The
input voltage should be a few volts higher to allow for voltage drops. Assume 20 volts. Lets also assume
that the load will draw 5amps. The power dissipation in the transistor will be Vce * Ic or (20-12)*8=40watt.
It may keep you warm in the Winter, but you will need a large heatsink with good thermal dissipation.

If you want to Boost the output current with a negative regulator, such as the 79xx series, then the circuit
is similar, but an NPN type power transistor is used instead.

Source :: http://www.zen22142.zen.co.uk/Circuits/Power/boosti.htm