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What I was thinking? - I was right! (Phantom power)

Started by SirEgno, May 28, 2020, 04:43:28 PM

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SirEgno

some years ago I started to build a mic preamp with phantom power supply.
I bought a 2x15v transformer as main power and for the phantom a... 2x12v transformer.
What strange drugs did I take to get this idea? How can I get 48v from 2x12v transformer?

I bought also every component to build this project and there is no charge pump or something similar.
Only a 48v zener diode.

davent

"If you always do what you always did- you always get what you always got." - Unknown

If my photos are missing again... they're hosted by photobucket... and as of 06/2017 being held hostage... to be continued?

SirEgno

you're right!
my knowledge is regressing  :-\
Are there some advantages using a full bridge rectifier?
like this:


Doubling the voltage the current is halved, right? the transformer is 0,5VA (2x0,25). so the current should be about 20mA?

davent

If i recall, peak voltage with a doubler is 2.8 times the secondary so i've gone with the ampere rating divided by the 2.8 factor. I've used the simple version in a number of tube amps for the high voltage rail, they've run with without issue for years. No idea whether the bridge may offer in improvements.
dave
"If you always do what you always did- you always get what you always got." - Unknown

If my photos are missing again... they're hosted by photobucket... and as of 06/2017 being held hostage... to be continued?

SirEgno

So, 24*2.8=67.2. That's why I also bought a 48v zener diode.

The schematic attached should be fine. But I think I have to add a resistor on the red circle. right?

Thank you very much for helping me!

davent

Your welcome.

The resistor, i don't know but, there is this project for a phantom  48v supply from Rod Elliot that uses a voltage doubler, he has a small value resistor in each power line.



https://sound-au.com/project96.htm
dave
"If you always do what you always did- you always get what you always got." - Unknown

If my photos are missing again... they're hosted by photobucket... and as of 06/2017 being held hostage... to be continued?