hi i dont now were to start.
i have a transformer which supply two 40V i.e +40 -40 and it has a current rating of 6.25 amps. I am going to connect it to an amplifier which needs DC voltage. Doese any one now what i have to do or can any one help me plaese.
Thanks alot from Sepand

 

You need two main components, the first is a full wave rectifier, which can be bought as a single component, or constructed using four diodes. This will effectively cause your Vac signal to become the absolute value of itself. Next you need a capacitor connected between V+ and GND to smooth out the "humps" of the signal. I can't remember the equation off the top of my head, but in general, you need a fairly large capacitor. It's probably best to feed this into a voltage regulator, regulated at the voltage which your require to power your amp.

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dual power supply. If you're amp is going to use the 6 Amps you're talking about then C1 and C2 should be taken big enough. 2x 10000µF sounds about right to me

Don't look at the numbers on the transfo on the scematic. They are the connections for one of the transfo's in my drawing software. You should look at the label on your transfo to see wich coil is wich. Also make sure you do not connect the 2 coils counter fased ... (or whatever the correct english word for it is)

last note: The secondairy side of the transformer should also be fused. put a fuse in both the lines from transformer to diodes. GND should not be fused. I already posted the circuit when i thought of it ops:

Attached Images

PSup.JPG (28.5 KB, 573 views)

 

hi what diodes shall i use and the person who left a message befor you said some thing about voltage reguilator do you think that is neede.
Thanks alot from Sepand

 

For safety use a 20A 200V bridge (graetz) rectifier, no need regulators for amplifier supplying.

 

Check this site out, under projects, amplifiers. The amplifiers all have a power supply schematic that you can base your circuit off of. I must say that this site is accustomed to use bridge rectifiers, rather than a quad diodes.
http://sound.westhost.com/projects.htm

 

This is how to connect your bridge rectifier like you asked. I can't upload the pic in private message so i'll do it here.

The 2 lines coming from the transformer may be swapped since it is AC

Attached Images

Bridge_rect.JPG (13.3 KB, 502 views)

 

hi sepand,

here is a helpful formula to use in determining the capacitance value & working voltage of your caps:

uf = [ {I * 1.0^6 / 1.5 } * 8.3^-3 ]

Working Voltage (WV) = 1.414 * Voltage Secondary (Vs)

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There's a simpler way of expressing that formula:

C (uF) = 5533 * I

 

2 x 10000µF will do just fine...