Need Help Voltage Regulator 12 vDC using 7812

[gamelektro]

I need Voltage regulator from ac to dc 12 v but using 7812

please tell me the schematic circuit?
or where i can download the schematic

 

[audioguru2]

You need a transformer to match your mains voltage with a 12VAC /1.5A output. Calculate the value for a fuse on its input.

The transformer feeds a bridge rectifier and a filter capacitor. The 7812 needs an input and an output capacitor as shown on the datasheet for the 7812.

 

[gamelektro]

C1 = 2000uF
C2 = ..?..
C3 = ..?..
D1 -D4 = what type diode must i use? 1N4001 or 1N4004

Please Tell me the value for C2 and C3 from the picture

 

[audioguru2]

A rectifier bridge or four rectifier diodes could be used in a 78xx regulated power supply project.

Look at the datasheet of the regulator IC to see the pins layout and to see what capacitors are recommended by the manufacturer.

Look at the datasheet of the rectifier bridge or the rectifier diodes to see their voltage rating. Check their prices. Sometimes a rectifier diode with a higher voltage rating costs less because it is more popular.

 

[gamelektro]

Hello Mr, what type trafo must i used? Trafo With the CT ( Center Tap ) or Without CT.?

The trafo 12v/1,5Amp not sold In my country, there only have  12v/1Amp.
I Have a trafo 12v/1 amp without a CT ( I buy it this morning) and 12v/300mA with CT ( already have it ).

So Mr which must i choose for the trafo to make the voltage regulator with output 12 Vdc, ?
Mr,  it is possible to make the Voltage Regulator 12vdc without 7812?, just using the trafo,dioda and capasitor.? Can we do that?!!!!
and  if we can do that please tell me about the picture schematic?

sorry if my english not very well?? Thank You

 

[audioguru2]

what type trafo must i used? Trafo With the CT ( Center Tap ) or Without CT.?

A 24V center-tapped transformer can be used with only 2 rectifier diodes. A 12V transformer needs 4 rectifier diodes to make the same DC voltage.

The trafo 12v/1,5Amp not sold In my country, there only have  12v/1Amp.

Then its load can be nomore than 12VA. It makes a DC peak voltage of 17V so the max DC output current is 12/17= 0.71A.

it is possible to make the Voltage Regulator 12vdc without 7812?

You could make your own voltage regulator with transistors but it would be more expensive and would not work as well as a voltage regulator IC.

just using the trafo,dioda and capasitor.? Can we do that?!!!!

Of course you can, but it won't be regulated.
Use a 10VAC transformer, 4 rectifier diodes and a big filter capacitor. The output voltage will be 12.3V if the mains voltage is the same as the transformer rating and the transformer has a full load. There will be some mains hum on the DC. If the mains voltage changes then the DC voltage will also change. If the load is reduced then the voltage will increase to about 14VDC.