Fixed Voltage Power Supply


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The fixed voltage power supply is useful in applications where an adjustable output is not required. This supply is simple, but very flexable as the voltage it outputs is dependant only on the regulator and transformer you choose. The maximum output current is 1.5A.

Schematic

This is the schematic of the Fixed Voltage Polarity Power Supply

Parts

Part
Total Qty.
Description
Substitutions
C112200uF 35V Electrolytic Capacitor
C2, C420.1uF Ceramic Disc Capacitor
C3110uF 35V Electrolytic Capacitor
D1, D221N4007 Silicon Diode
BR112A 30V Bridge Rectifier
U11Regulator (See Notes)
T11Transformer (See Notes)
S11SPST 2 Amp Switch
F112A 250V Fuse and Holder
MISC1Heatsink For U1, Line Cord, Case, Wire

Notes

  1. Since this project operates from 120 (or 220, or 240, etc.) volts AC, it MUST be built inside a case.
  2. U1 will reauire a heatsink.
  3. You will need to choose T1 and U1 to match the voltage you want. Use the table below as a reference.

    Output Voltage
    T1
    U1
    5V6V, 1.5A7805
    6V6V, 1.5A7806
    9V12V, 1.5A7809
    12V12V, 1.5A7812
    15V24V, 1.5A7815
    18V24V, 1.5A7818

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Comments

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anonymous
Fixed Voltage Power Supply
Thursday, September 26, 2013 10:53:29 AM
shouldn't the T1 be at least 2V more than the required voltage?
CHARLIE
Fixed Voltage Power Supply
Sunday, June 03, 2012 5:04:31 PM
how to generate a one volt power supply from an main ac supply.
Greg Taylor
Fixed Voltage Power Supply
Tuesday, March 06, 2012 9:53:13 AM
I am involved in a senior project that requires me to build a 6V 1.5A power supply. How can I determine what the values I need for the Fixed Voltage Power Supply schematic that is provided from your website? Your help is very much needed. Thanks.
anonymous
Fixed Voltage Power Supply
Wednesday, February 01, 2012 4:58:05 AM
The 1/2/3 are the pins on the LM78xx. I have a question though. Since I'm going for 5v out, I imagine that I could replace the LM78xx with the R-785.0-1.0 from RECOM? Better efficiency but would only have 1A out, for me that's fine as it's only to power USB type devices.
anonymous
Fixed Voltage Power Supply
Tuesday, January 10, 2012 10:33:50 AM
can u please tell me why 3 & 2 is written in U1
arslan
Fixed Voltage Power Supply
Saturday, December 03, 2011 4:29:18 AM
its very easy ,use ( LM7805 ) to get 5v DC power supply
anonymous
Fixed Voltage Power Supply
Tuesday, October 05, 2010 11:51:28 PM
Should the Switch (S1) not be on the Positive / Live side before the transformer?
yuki
Fixed Voltage Power Supply
Saturday, August 28, 2010 9:35:00 PM
what is the purpose of D1, D2, C2, C3, and C4? And, why you didn't include resistor in the filter and for the load? thanks... hope you answer my questions ASAP...thanks again
Sandro Pace
Fixed Voltage Power Supply
Thursday, August 05, 2010 8:01:21 AM
Hi, I would like to build a power supply that can give out 24V DC at 5A from 240V AC. What parts in this circuit do I need to change to achieve this. Thanks.
ARSALAN AKRAM
variable power supply
Saturday, January 02, 2010 10:57:21 AM
ASSALAM o ALAIKUM! sir i want the circuit which regulate from 1.2 to 30 but i want that circuit having transformer whose AC input is 220 volt i have seen your circuits in your circuits AC input in the transformer is 120. plz give me the circuit as soon as possible i shall be very thank ful to u for this act of kindness
casian
Fixed Voltage Power Supply
Sunday, August 02, 2009 5:11:11 AM
what is fuction of diode D2 in the circuit?
Numlock
Fixed Voltage Power Supply
Monday, March 30, 2009 4:56:20 AM
Hello, I've been building grow light panels using cement mixing tubs from a home center and high output LEDs. The combination of 1 blue (465nm) to every 3 red (650nm) works very well. The LEDs that I use are 10,000mcd with iF of 30ma at 3.6vF. To this point I have been buying used 36VDC golf cart battery charging transformers. These chargers average 36VDC with spikes up to 36.2VDC so I run multiple series of 10 LEDs with 6.8Ohm 1/4 watt resistors per series. I use a grid of 17 x 21 with 3/4" on center. This leaves 3 LEDs unaccounted for so I place them on the panel enclosure as 'decorations'. My problem is that all of this depends on golf cart battery chargers remaining available and inexpensive. I find that it is getting harder and harder to find then. I think that most carts are now operating at 24VDC or 48VDC and that 36VDC is an obsolete design. That just means that I need to build my own. The design pulls 1,080ma of current and draws 39,100.32mw of output power. I have looked at 18VDC but an ideal design pulls 2,160ma of current at 18VDC. 2A is not quite enough and 5A transformers are ridiculously expensive. Is there a design out there for a 110/120VAC to 36VDC power supply? Thank you
Bablu
7-segment display-com.anode type.
Wednesday, January 14, 2009 10:18:47 AM
I've Constructed a CKT Of 7-segment display anode type which uses conman anode type display.I've obtained the output which mean display shows digit from'0-9' but whats happened the no. is appearing randomly.please send me a solution on it
Mir Qadeer Ali
Fixed Voltage Power Supply
Saturday, August 23, 2008 3:40:12 PM
i have constructed 230v ac to 9v dc, by using 12v transformer and 7809 regulator, now am in need of 6v dc, what modification i should from the above, or i have to built seperate circuit by using 6v transformer and 7806 regulator, let me know by my email as soon as possible , thank you
Graham
Fixed Voltage Power Supply
Wednesday, May 21, 2008 1:01:12 AM
Hi, Please help me I need to step down DC voltage from +/-13 -14.4V to 11.5 - 11.9V @ 3A DC can you help?
Stram
Fixed Voltage Power Supply
Tuesday, April 29, 2008 11:22:24 AM
a friend from U.S.A. gave me an HP Printer/Scanner without a power supply, since i am fond electronics assembling, i want to assemble a 24V greater than1.5A fixed regulator. Please help and provide me Thank you very much, STRAMM
Maxspower
Fixed Voltage Power Supply
Tuesday, April 15, 2008 4:37:08 PM
"What si the prupose of the fuse and capacitors" . . . love it! LOL
sammaking
Fixed Voltage Power Supply
Tuesday, February 26, 2008 5:31:39 AM
please help me out with the circuit diagram of a variable dc output (-12,+12 & +5v) power supply of 110v ac input
eliya
Fixed Voltage Power Supply
Tuesday, February 19, 2008 12:16:11 AM
how about if the output voltage is 25 Vdc and the maximum output current is 5 Ampere? how the circuit going to be?this power supply will use the source from 240 Vac.can u please help me on this problem.reply to my email.thank you
mebrahtu
Fixed Voltage Power Supply
Friday, January 04, 2008 1:43:54 AM
In the above citcuit u1 means transistor please explane
Joe Soup
Fixed Voltage Power Supply
Tuesday, January 01, 2008 1:10:54 AM
What is the requirement on the voltage capacity of the .1uf disc capacitors? I looked at radio shack and the only ones they have listed are 50v. Would this be too much, since the other voltages seem to be 35v?
demz
Fixed Voltage Power Supply
Monday, December 10, 2007 4:31:16 AM
how about if the maximum output of the fixed voltage power supply is 6ampere?
manu thakur
Fixed Voltage Power Supply
Sunday, December 09, 2007 7:28:46 AM
i want to make a power supply of 5v & 12 v by using a single transformer help me....
Nauman Ali
Fixed Voltage Power Supply
Saturday, December 08, 2007 4:04:55 PM
its ic pin configration may be wrong because pin 1 is input and pin 3 is out put of that ics but in the circuit its pin look wrong
jason
Fixed Voltage Power Supply
Sunday, December 02, 2007 5:26:34 AM
please give me the circuit diagram of 24V/5a power supply 220v.send in my e mail
A.senthilkumar
Fixed Voltage Power Supply
Wednesday, November 28, 2007 7:14:02 AM
I need circuit for 24V,5A D.C.output
anonymous
Fixed Voltage Power Supply
Sunday, November 18, 2007 9:53:59 PM
What would be the values for a 13.8vdc 20A power supply--for a Ham Radio?

(Editor's notes: Not going to happen with that regulator.)

Joe Baltro
Fixed Voltage Power Supply
Tuesday, November 06, 2007 6:38:39 PM
Hi every one, i need 24V/5A dc form an 220v ac so if any one knows the circuit design please post it in the site or send it to my e-mail Thanx
anonymous
Fixed Voltage Power Supply
Saturday, October 27, 2007 3:14:22 PM
what is the purpose of the fuse, and capacitors please?
vicky
Fixed Voltage Power Supply
Thursday, October 04, 2007 4:37:58 AM
i want to build a 5-volt fixed power supply.kindly help me.

(Editor's notes: The diagram is right above the comments...)

anonymous
Fixed Voltage Power Supply
Sunday, September 30, 2007 4:55:21 AM
please give me information about the design of 10 volt power supply ,0 to 3 ampere current
priyantha
24 volt to 12volt dc regulater
Friday, September 28, 2007 9:06:21 AM
pls give me 24volt to 12 volt diagram
anonymous
Fixed Voltage Power Supply
Thursday, September 27, 2007 10:01:20 AM
CAN ANYBODY CAN DRAW SIMPLE DIAGRAM OF 230v AC 50 HZ 12vdc 10A
triripa moabelo
5 volt and 1 Amp power supply
Thursday, September 13, 2007 10:49:28 AM
i need more information about switch mode power supply (5V and 1 Amp as the output. you can send me circuits diagram and other relevant infomation looking forward for your response
Nayanvir
about 7812 ic
Saturday, September 01, 2007 12:20:37 AM
hello Sir in my project current rating of ic 7812 is not given. how much current i get from it??????/ different current ics are available ???????
dapo odukale
Fixed Voltage Power Supply
Sunday, August 19, 2007 3:46:34 PM
how do i have the various output of -5v,+5v,-6v,+6v,....-18v,+18v on the same circuit.
Samir Pandya
+/-12VDC from 24VDC power supply
Thursday, August 16, 2007 7:57:16 AM
Please send me ckt. diagram for +/-12VDC from 24VDC power supply urgently.
anonymous
Fixed Voltage Power Supply
Wednesday, August 15, 2007 3:13:06 PM
FIX THE PIN NUMBERS ON THE SCHEMATIC!
anonymous
Fixed Voltage Power Supply
Wednesday, August 15, 2007 10:29:50 AM
I suggest that you omit C3. The 7800 series of positive regulators have been known to oscillate with large-value electrolytics connected close to their output pins. The 0.1uF provided by C4 is sufficient to improve transient response without the risk of oscillation. In general, large output capacitors on 7800-series positive regulators invite instability.
shashi prashant
Fixed Voltage Power Supply
Friday, August 03, 2007 1:53:52 AM
want to build 12V 1amp constant DC supply with transformer (220V AC 50Hz). thanking u.
sunil patil
Fixed Voltage Power Supply
Monday, July 30, 2007 7:02:15 AM
please give me some information about power supply design for -5 volts , 0 to 5 amperes
anonymous
Fixed Voltage Power Supply
Tuesday, July 17, 2007 7:25:47 AM
I'm having trouble finding the parts at local stores in Maryland. Do You know any good, reliable stores online or local
Russ Peecook
Fixed Voltage Power Supply
Sunday, July 08, 2007 2:13:03 PM
I built the fixed power regulator and blew up the IC. It seems you have the numbers wrong on the schematic. Pin 3 the left pin should be pin one and pin one should be pin three. In effect I grounded the input and seemed to fry the IC. I was using Radio Shack 7812 IC chip and the numbers are printed on the back but it does not indicate input, output , and ground. After research on the net and looking in the ARRL handbook I figured it out. Must have been a typo. please correct this before someone else ruins a IC. Good circuit now. Thanks Russ
Jeff Leites
Fixed Voltage Power Supply
Wednesday, July 04, 2007 2:04:29 PM
The pinout for U1 shown in the schematic is wrong! I just fried my regulator, and almost fried my rectifier, because I trusted it. The correct pinout is: 1 - voltage in, 2 ground, 3 voltage out. You can verify this on anyother web page for these 78xx regulators. Here are two: http://www.geocities.com/siliconvalley/2072/3pinvolt.htm http://www.iguanalabs.com/7805kit.htm Now my project is delayed until I have time to buy a new regulator.
Wes
Novoice wants to build fixed 7.2 volt power supply using a 12 v gel cell for my DVD CAM
Saturday, June 23, 2007 5:52:50 PM
I'm a novoice and want to build fixed 7.2 volt power supply using a 12 v gel cell for my DVD CAM. Can anyone help? Thanks.
waqar
Fixed Voltage Power Supply
Saturday, May 05, 2007 2:20:40 PM
I need calculatoion of 18V power supply with 230V(50Hz)AC as an input input..it should have 5% ripple and 1 A at out put..
Kwaito
Fixed Voltage Power Supply
Sunday, April 22, 2007 8:24:08 AM
want to build 9V DC supply without transformer (220V AC 50Hz)
m.durga
SWITCHE MODE Power Supply
Friday, March 30, 2007 11:31:53 AM
I HEARD THAT THE CIRCUITS OF SWITCHED MODE SUPPLY IS TOO DIFFICULT TO DESIGN. IS THAT TRUE? Y SO? THEN WHICH TYPE IS EASY THAN THIS? WHAT IS THE ADVANTAGES OF SWITCHED MODE 7 OTHER POWER SUPPLIES?
vinoth kumar
Fixed Voltage Power Supply
Monday, March 26, 2007 2:36:47 AM
i saw all circuits in this website wonderful and useful.. but i need for my portable application is to convert 6V/4.5A to 5V/3A.... while i connecting 7805 regulated IC, IC get heating more with heat shink also and IC get damaged... pls suggest me the circuits... 6V/4.5A Motor cycle Battery...

(Editor's notes: 3A is way too much for the 78xx series regulators. They are 1.5A max.)

anonymous
Fixed Voltage Power Supply
Thursday, March 22, 2007 11:02:05 AM
how to build regulated power supply without using the regulator IC ?
karthik
Fixed Voltage Power Supply
Wednesday, March 21, 2007 7:42:18 AM
this is very usefull to me
TAYFUN KESİMOĞLU
Fixed Voltage Power Supply
Wednesday, March 21, 2007 5:46:44 AM
hello I want make a fixed voltage power supply. How the make 200v to 50v ...what can I use transformer?
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