Reducing Voltage in a safe way.

[darkm4n]

Redicing Voltage in a safe way.

Hi ,

Maybe this trand it's a little stupid .. i'am a begeiner and i have to admit i don't know fundamental stuff ...

How i can reduce the voltage from a 2x38 VAC 500 VA Toroidal transformer , filtered and stabilized at 55 V to 40 V or even 45 V in a safe way .
Adding some resistors ???

Thank's . Mihai .

 

[markp]

Use a voltage regulator circuit like the one from The Audio Amatuer for the GFA-555 amp. Do a search and you will find the schematic on line here. It does a great job and is easy to build.

 

[darkm4n]

Could you ... ?

Hi ,

Could you post the schematic here
? Please ... ?

I can't find it .

Thanks

 

[darkm4n]

Or ...

Or somebody alse if everyone know a good 40 V DC regulator for a 400 W amplfiere ( high current needed ) please help .. or other method of reducing voltage .

Thanks

 

[markp]

here is the v reg

 

[darkm4n]

Nope ...

This is for 60 V .. i need one for 40 V . Thanks

 

[markp]

Change the zener voltage.

 

[markp]

It is very adjustable with the pot and using different ref voltages(zener) and handles lots of current with most any decent output transistor. I've used mjl21193/4, 2sa1302/2sc3281, mj15003/4 and many others.

 

[darkm4n]

Heh ??

Where is that pot ??

 

[peranders]

darkm4n, what is your purpose of all this? High current?

What is 40 volts used for?

 

[darkm4n]

Amplfier

I'am for an 350 W 8 Ohm amplifier , and i use the PSU from the M250 Amplifier witch is not exactly was i thinked it is .. and i decided to try those 350 W .
The PSU is rated at 55 V and i need to reduce it to 40 V

Is there any methos of reducing the voltage with some resisistors ??? resisistors ??? resisistors ??? resisistors ???

Not an voltage regulator . Because i like the simple way to do it 🙂

Thank's
Need URGENT answer !

 

[peranders]

Why do you want to reduce it?

50 V gives you approx. 156 watts at 8 ohms

 

[darkm4n]

On the specs of that KIT amplfier it's saying that 45 V is the maximum and unsafe voltage , 40 V it's needed

thanks

 

[darkm4n]

Exactly it consume 7 AMP

 

[peranders]

Can you give a link please?

45 volts gives you only around 100 watts. Where came the 350 watts from?

 

[darkm4n]

http://www.adelaida.ro/kituri.php

And scrool down , a it's kit : KIT AD-020v5 350 W x 1 8 Ohm
You click : vezi prospect and there is the info about the amp .. but it's in romanian .. you can understand a little ..

Look there and see .. i will get 2 of this .. so how i reduce that voltage ??

 

[darkm4n]

?????????/

 

[millwood]

two suggestions:

1) if you are having trouble following this thread, you may want to start with something simpler, like a P3A or Citation 12 (my favorite).

2) it may be simpler to get the schematics of the amp you wanted to build, and see if you need to use different devices and resistors to make it work for your transformer.

3) it is impossible to get 300w @ 8ohm out of 45vdc rails. Assuming perfect rails and perfect lossless transistors, you get about 250w on 8ohm. Not sure how that designer found the remaining 100w.

 

[AudioFreak]

From what I can decipher from the desinger's literature, it appear to be a bridged amplifer.

 

[darkm4n]

Is there something simple .. to reduce that voltage ??
Ohm law may help ??